CA2128769A1 - Microminiature, monolithic, variable electrical device and apparatus including same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
MICROMINIATURE, MONOLITHIC, VARIABLE ELECTRICAL
DEVICE AND APPARATUS INCLUDING SAME

A microminiature, variable electrical device, such as a capacitor (40a), comprises an elemental DMD SLM (40'), which includes a substrate (43) and a member (145) spaced therefrom and mounted for movement by appropriate facilities (42, 44). A control signal (102) is applied to the movable member (145) to produce an electric field between it and either the substrate (43) or an associated control electrode (46a). The field moves the member (145) toward or away from either the substrate (43) or an associated output electrode (46b) to selectively adjust the spacing therebetween. The field is produced by addressing circuitry (45) associated with the substrate (43). The movable member (145) and either the substrate (43) or the output electrode (46b) function as capacitor plates, and the spacing determines the capacitance thereof. The capacitor (40a) may be placed in series (Fig. 4) or in parallel (Fig. 3) with an input signal (114) applied to the movable member (145). The movable member (145) substrate (43), control electrode (46a), output electrode (46b), addressing circuitry (45), and other elements of the capacitor (40a) comprise a monolithic structure resulting from the use of MOS, CMOS or similar fabrication techniques. Multiple capacitors may be included in transmission lines (Fig. 20), antennae (Fig. 22), couplers (Fig. 21), waveguides Fig. 25) and other apparatus for digital or analog tuning or capacitance adjustment thereof by selective operation of the addressing circuitry (45).

Description

J, M~C~ROM~ M[ONOLIl~C, ~TAlRLABLE ELECTRICAL
DEVICE AND A~F'PA~TU~3 INCLUDING SAl~
~:~3 ." :
BACR;GROUND OF llE~ INVE~IION

2 :
~ ~ ' 3 Field of the ~v0n~0 ~, 4 . j llle present ~vention relate~ to a microminiature, monolithic, 6 variable electrical device, and, more particularly, to ~uch a device ;', 7 constituted of a ba~ic '~uilding block" -comprising a deformable-mirror :~ 8 spatial lig~t modulator ("SLM") ~nctioning as a capacitor or switch.

,i..:l ~3~ 10 Prior Art i l~

12 An SLM is made up of sn a~ay of small mirror~ or re:~ector~, 13 each of which i~ capable of ac~;ing a~ a select~ve ligh~re~ective pi2cel.
14 Esch pisel refleet~ incide~t light alo~g a path w~ich depends on the ~ .~
~` ` 15 po~i~on or orientation of it~ mirror. I~pically, each pi~el milTor is 16 movable (eg. by deflec~on or deformation) between a normal, first 17 po~itio~ or o~entatio~ d one or more second po~itions or 18 orien~ations. In only one po8ition --either the normal po8i~io~ or one . ..
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of the second positio~-- each p~el directs the iDcident light along a 2 selected path to a primary light-receiving site, for example, into an 3 optical system and from there onto a view~ng sur~ace or light-4 se~tive paper. In a~l other pi2cel m~ror positiorls, i~cident light i5 not directed along the selected path to the prsmary ~,ite; rather, it i8 6 directed to either a secondary site or to a ' light 8iIlk" which a~sorbs 7 or eliminates the light which, therefore, does not reach the light-8 receiving site.
: ~
9 .
An array of pi2~els may be used to reflect incident light in a ~ ;
11 patte~ to the pr~ site. A pi~el array may take the form of a 12 square or other othogonal matri~c. In this event9 the pO8itiOIl of each 13 pi~cel mirror, which position i8 individually corltrollable by as~ociated 14 addressing facilities, may be altered i~ a rasterized display to genera~e a ~ideo presentation. See commo~y a~,signed US Patent~"
,i~ :
16 ~,07g,544; 5,061~049; 4,728,185 and 3,600,7g8. ~3ee al~7o USPaterlt~7 17 4,3~6,730; 4,229,732; 37896,338 and 3,S86,~10. A pisel array may 18 al80 take other forms, for e~ample, that of a rectallgular matri~, the ;
-; 19 length of which i9 nlUCh greater tha~ its width. Irl thiY latter event, ;,!j 20 the poE~itions of the p~Ql ml~0~3, as determined by their associated 21 addres~i~g facili~e0, may be indi~idu~lly, selectively altered so that " ~ .

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the reflected light p~nts characters ~ quasi~ e-at-a-l;ime fas~ion on 2 light sensitive paper. See commoDly assignedUS Patents 5,101,236 3 and 5,041,851. In both eve~ts, and in other use e~riromnents, 4 appropriate arrays and configurations of pi:lcels/mirrors enable SLM'8 to modulate light i~l amplitude-domin~nt or phas~domin~nt mode~.

, ~
7 There are at least four genera of SI~8: electro-op~c, mag~eto-.~ 8 op~c, liquid crystal and de~ectable (or de~ormable) mirror. The latter 9 gen~s, oPcen referred to as a DMD --Deflectable (or Deformable) ~or Device or Digital MicroInirror Device- includes a ;
:~ 11 micromechanical alTay ofelectronically addre3~able mirror elements.
12 The mirror elements are reflectors each of which i9 individu~lly 13 movable (e.g., deflectable or de~ormable), a~ by rotation, deformatio ,!i '~ 14 or piston-like, up-and-down movement into selective ref~ec~g 15 configl3~ation~. As noted above, each mirror constitute~ a pi~cel which ;, 16 is capable of mechaI ical mo~reme~t (deflection or deformation) in ;~` ! 1~7 re8po~e to an electrical input. Ligh~ incide~i; oll each mirror may be 18 selec~ ~ely modulated in its direction and/or pha3e by reflectioIl firom ~"3i 19 ea~h selectiYely m oved or posi~oned rmkror. ~b date, D~3D SI~U~8 ~,~J
2û have fou~d use ~ op~i~ correlation (e.g., in Van der Lugt matehed ;
21 ~lter co~relators), spectrum analysis, optiical c~o~sb~r swii~g, Y.i ' `

frequency e~cision, high definition displays (e.g. tele~rision), display 2 and display projection, ~erographic printing and neural networks. ~ -4 There are several species of the genus "DMD SLM", including cantilever-and torsion- beam type elastomer type, and membrane ; 6 type. A fourth species of DMD SLM which is structurally related to ., ',';J 7 both beam types, but is operationally related to the ela~tomer and 8 membrane type~, is the so-called fle2~ure-beam type. Addressing --9 that is, selec~vely mov~ng- the pi~cel~ of DMD SLM'8 ha~ been :.,~ , .
ac~ie~led by electron-beam input, optic~lly or, as preferred today, by 11 monolithic, t~in film or hybrid integra$ed circuit~, w~ich include ;~1 12 MOS, CMOS and fi~nc~onally similar devices.

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14 Specifically, it has been found convenient to produce integrated addressiIlg circuits monolithically with the ~pi~els using coIIven~onal ;
16 MOS/CMOS proeessing te~niques to fo~ the addres~i~g circuits i~
17 alld on a 3ubstrate (typically silico~) with the pisels spaced al~ove the 18 sub~trate. The addre~s~g circuits can be planarized and overlain by ~i~ 19 their re~pec~Ye pi~cel~ to limit light pene~a~on thereinto, thereby 20 reducing light dif~ o~ fhm the addres~ g circuits and ii~om the .:....................................................................... ~
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.,1 ~ubstrate. The addressing circuit~ may affiect pi~el positio~s in .,2 analog, bistable (b~nary) and tristable fashio~s.
, , 3 :;
4 Can~lever-beam arld torsion-beam types of DMD SLM78 eaoh ::.

5 compri9e a relatively thick (for rigidity and low complia~ce) mi~or or 6 reflective metal member typically integral with and supported at it9 i~ . 7 edges by one or two relatively thin (for high compliance) cantilever '!f 8 beam~ (or spnngs) or torsion beams (or spnngs). Each mirror i~
9 structurally supported by its beam~ tnd separated ~om its aseoc-ated ` ;f 10 addre~si~g circuit and from an control or addres~ electrode which i8 a 11 part of or controlled by the addressing circllit, 'by a spacer or 9upport 12 post to which the beams are connected or a.f~ached.

14 Ab3ent a deflecting force applied to e~ach mirror or metal 1~ member, the mi~or i~ maintailled in its normal posit;io~ by it~
16 be~m(s). When the COIltrDl or addre~ electrode is energized ~y 17 ha~ g a ~voltage fiom the addre~ing circuit applied thereto, the 18 re~ulting elect~ic field mo~e~ a por~on of the miITor aligned with the 19 elecb~ode along the field linea Such movement re~ults firom ;~
20 coulo~bic or elestrosta~c attraction of the portion of the mirror 21 toward (or le~ typically repul~ioll a~ay ~om) the elect~ode.

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Can~lever or torsio~l bending occurs preferentially at the thin 2 beam(s). Such bending stores potential energy in the beam~s) 3 a~sociate~ with the defiected m~rror. The stored potential energy, 4 which tends to return the mirror to it~ normal po~ition, is efEective to 5 achieve such retur~ when the coIltrol or addres~ electrode no longer 6 attracts (or repel~) it.

. , .

8 Once the adclressing circuit and its control or addre~s electrode 9 are fonned in or on the substrate, a plananzing orga~ic photo-resist 10 may be spun onto the ~ubstrat A t~inmetal layer, 8uch as 11 alum~num, is the formed on the smooth surface of the photoresist, 12 and the layer is patte~ed to form precNrsors of the mi~ror~ aDd their 13 a~ociated be~ms. Irhe thicl~ness of the mixror precur~or, but not the 14 beam precur~ors, may be inc~eased by selec:tive deposition, mssl~g, 15 etc~i~g and related MOSlCMO~;-like procedures. Ihe photoresi~t is 16 removed from under the ~r and beam precursor3 to form a well 17 or air gap between each mirror, on one hand, and it~ addres~
., . ~
18 elect;rodes aIld the substrate, on the other hand.
. . .

.: 19 `''''~,~J 20 Durinig delle~ioIl, the attraeted mirror porl;ioIls move into and 21 out of the wells. 'l he ,direction taken by reflected, ~ride~t light ~, 6 .,, ~

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depends on the position or orientation of each mirror and, hence, on 2 the energization state of the as~ociated control or addre~ electrode.
:) .
3 In this type of DMD SLM the thick mirrors are ~nd remain relatiYely 4 flat, with their positio~s or orientation~ relative to the inc~dent light ~nd the ligh~receivi~g site be~ng selectiYely altered to dete~ine the 6 path of reflected light.

8 One early type of DMD SLM --the elastomer type-- includes a 9 metallized, relatively thick: ela~tomer layer. A la~er, related type of 10 DMD SLM illcludes a relatively thi~ metallized polymer membralle 11 st~etched over a spacer grid or other 8upport structure. I'he 12 u~deformed planar elastomer layer separates the metal layer thereon 13 from underlying addresF,ing facilities. The spacer grid effected aD air 14 gap or separation between ~d-delineated E~egments of the normally 15 undeformed and planar membrane and co~esponding underlying 16 add ressing facililies. Each segment of the metal layer on the 17 elas~omerand themembralle constitutes api2cel. Engergization of a 18 control or addre3s electrode a~ociated with each metal layer each 19 metal layer segment elestrostatically attracts (or repels) the metal ~, 20 - segmenLt to cur~il~early deform ~e as~ociated"lormslly flat, related -;
21 ela~tomer or membrane segmen~ out of its rlonnal, u~deformed, ~ ~ ~
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planar configuration and toward (or away from) the electrode, 2 ~hereupon the curvi3inearly deformed met ~egment acts as a 3 miniature spherical, parabolic or other curved mirror.

. . .
Deformation ofthe elastomer andmembrane stores potential 6 energy therein. Deenergization of the co~trol or addre~s electrode . 7 permits the ~tored potential energy in the ela~tomer and membrane 8 segment to return it to its normal fla~ configuration. Incident light ", 9 reflected by each m~niature mirror may be concentrated into a ~, 10 relat;ivelynarrow cone thati~ rotationally ~ymmetric. Eachpi~el 11 could, therefore, be a~sociated with a S~lieren stop, compn~g a ` ! 12 single, central obscuration having a po~ition and size to block the 13 light re:dected by the ~at or unmodulated pi:~:el mirrors. Modulated, ;;, 14 curved or deformed pi~el mirrors direct a ~rc~lar patch of light onto the plzlne of the 8top, the patch i~ centered on,butis now largerthan, 16 ~he 3top's central obscura~on and,therefore,traversQ a selected 17 direction and reacheq a eelected eite.
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~; 19 A~ ~nth DRrD SIaMrs ofth~ bea m type, D M D SI~Yr~ oft e - mernbrane type have E180 recen~y bee~ produced by forDlLng a hybnd 21 ~ltegrated 888ernbly compnsDng an array ofrela ~ ely thick,low . ~

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compliance, separated, ~at pi~el mirrors each supported by relatively 2 thin high compli3nce members. The memberss may, a3 in the past, be 3 metallized segments of a polymer membr~e or separate met~ed 4 polymer membranes. More typically, the members are E~egments of a 5 compliant metal membrane or thin, stretchable s~d highly compliant 6 or project ions co~ected to or integral with their mirrors. The metal 7 projections (or metal membrane, as the case may be) space the 8 mirrors a first distance above a silicon or other substrate hav~IIg 9 fonned therein and thereon address~ng circuits,. Underlying 10 addressing circllit~ are separated by air gaps from their asaociated 11 pi2cel mi~rors when the latter reside i~ their norms31 positions. When -3 12 an addressing c~rcuit i8 appropriately energized, its pi~el mirror is 13 displaced or deflected toward the 3ub~trate by electrosts3tic or 14 coulombic attraction. If the mirrora sand the met~ I membrane or the metal projection3 are of 9imil3r thil~e98, the di~placed mirror 16 cur~elillearly deforms. If the mirror3 are ~ubstantially thicker than 17 ~e ~u~rounding metal membr~ne or the metal projections, eac 18 displaced mirror remains essentially ~at while the metal projections s l 19 tor the me~l membrane~ immediately ~tretch and de~orm to permit ~., 20 the mirrors to de~ect up-and-dowIl in pi~ton-like fa~io~. The 21 re~ultant displacement pat~rn --of th3 curvelillearly or tran~versely --. "i ,, :
., 9 ..

, -displaced mirrors-- produces a corresponding amplitude or phase .. 2 modulation pattern for reflected light.
:. 3 .
4 A DMD SLM of the ~de~ure-beam type include~ a rela~vely 5 thick fiat mi~Tor supported by a plurality of relatively thin can~lever~
6 torsion beams. In an e~emplaryfle~ure-beam type of DMD SLM, the -7 mirror is a rectangle or a square and each beam e~tends partially 8 alon~ a respective side of the m~rror ~om a spacer or support po~t to 9 a corner of the beam. In thi9 type of SLM the beams e~tend parallel 10 to the mirror's side2, while in the cantilever- and torsion-beam SLM'~, 11 the beams typically ertend ge~erally perpendicularly or acutely away 12 firom the sides of the m~rrors.

14 When a mirror of a fle~ure-beam device i9 attraoted by it8 15 cont;rol or address elect~ode, the beam3 uDdergc p~marycall~lever 16 bending and secondary torsion~l bending to effect piston-like 17 movement or defilection of the flat mi~or w~th ve~r 81ight tl~ing of :;', . ~:

18 the ~at mirror about an axi9 parallel to the direction of piston-like ~ -19 deflec~on a~d perpendicular to the mi~or.

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Further general info~mation on SL~s may be obtained ~om a 2 paper entitled "De~ormable-MiITor Spa~l Light Modulators," by .'. 3 Larry J. Hornbecl~, presented at the SPrE Critical ,Review Seriest '' 4 S~atial Li~ht Modulators and APPlications III. in San Diego, CA OIl 5 August 7-8, 1989 nd publishedinVolwne 1150, No. 6, page~ 86-102 ,~ 6 of the related proceedings.
. ~ 7 ,.~., ,,:, 8 All DMD SLM~s compri~e aIl array of indi~ridually movable .:
,~ 9 (de~ec~able or deformable) m~rrors, pi:~els or ligh~re~ecling surfaces.
',~ 10 As discussed in commonly a3~igned US Patent 5,061,049, DMD's have 11 been recognized a~ also compnsing, in effect, air gap capacitora 12 Apparently, however, the capacitive nature of DMD SLM's has been 13 relied on primarily for analysi~ of the operation of the DMD's. Tbat ~ :
~'b'~ 14 i8~ while the optical characteristics of DMD SLl!~ have, and co~tinue ~, 15 to be exploited, little work has bee~ do~e w:bich capitalizes on the 16 illherent electlical ornon-light-reflecting~lature of these devices.
1~ ~
18 One object of the prese~t L~vention i~ the provision of a ,.
"~ ' 19 micromirliatllre, monolithic, vanal~le electrical device, such as a `~! 20 cspacitor or 9witch, comp~sing a DMD, qua or switch, and of v~nou~ ~ :
~,.'. 21 app~tus compnsing or ill~luding 9uch a dence. Apparatus ulilizing -~?
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variable DMD devices, such as capacitors arld switche~"ncludes 2 t~ansmission lines (such as variable irnpedance micro~trip lines);
3 variable impedance matrhing, transform~ng and filter networks;
4 variable-impedance or ~equency-agile alltemlae (including patch, 5 9piral and 910t) which are tunable a~ to radia~on pattern, ~equency 6 and wavelength; variable-impedance or ~equency-agile coupler~
7 (including symmetnc, asymmetnc and rat race); variable FIN lines 8 aasociated with waveguides; waveguides ~er se. switches for optical 9 waveguides and electrical transmission line9; circ~ut operational 10 controllers, for e~ample, to tune compensate or control high ~equency 11 oscillator~; and true time-delay networks for phased array ante~mas.
12 Because of the operating mode of DMD's, ~a~ious apparatus in which 13 the DMD-derived device~ of the pre~ent i~LventioIl are inclllded, may 14 be digitally or selectively variable or tunable. :~ ~
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SIJ~RY OF I~E INVENIION

3 W~lth the above and other objects ill view, a prefe~ed aspect of 4 the present in~rention contemplates a microminiature, monolitbic, , 5 variable electrical capac~torcapable of a~ectin~ a time-varyinginput ;' 6 signal.
. .

8 The capac~torincludes a substrate. Amember, which may be ~, 9 electncally conductive, i8 monoli~hically formedwith and ~paced from 10 the ~ubstrate. The member aIId the substrate act as the re~pec~ve 11 plates of a parallel plate capacitor.
~, 12 13 A mountiIlg facility, such a~ a compliant beam, membrane or s........................................................................ ~ :
~; 14 hinge, mounts the member for deflectio~ of a portio~ thereof toward 1~ and away f~om the subst~a~. The mou~tillg facility ~tores poten1;ial 16 e~ergy thereinL when the beam por~;ion deflects out of a no~
~ 17 po~ition toward or away f~om the &ubstrate. lhe stored ellergy tend~
,..
~i 18 to retu~ the de~ected member port;ion to its nolmal po~ition.
.. ..
,~,i 3' 20 A facilil;y selecl;ively deflects the mem~er portio~ to vary the ~ ;
- ~ 21 capacitaIlce. The defle~g fas:ilit~ may comp~ise a conl;rol elect;rode ~''J
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spaced from the beam in the direclion of deflection of the beam 2 portion toward and away from the substrate. The control electrode 3 and the beam are capable of hav~g a control signal impre~sed : .
4 ~herebetween. Thi8 control signal produces a field between the besm 5 portion and the conl;rol electrode. The field deflects the beam portion 6 out of its norm~l position toward or away ~om the substrate. The ~;
7 cont;rol elec~rode may be a conductor formed on the substrate or may 8 be aregion ofthe substrate itself.
: :

Facilities are provided i'or applying the illpUt signal to the 11 capacitor. The input signal i8 affected as the capacitance of the :'1 :
:~12 capacitor varies.
l 13 14 The mounting facility may be, constitute a metallic or ` ~ 15 elastomeric membrane, and may be iIltegrally formed with the .iJ
16 member a~d w~th the ~nput-signal-applying facility. The mounti~g 17 faci3ity may also islclude a tor~ion beam or a cantilever beam or may ~., , 18 be a ~le~ure ~ystem made up of a plurality of combined cantilever alld 19 torsion beams. Deflection of the member may bc rota~oIIal or pi~to~-;~20 - like.
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The mounting ~acility may al90 include an insulative BpaCer or 2 a conductive post supporting the beam or membrane, which has :`
`` 3 formed therein a well residing below the member. The spacer or post 4 are preferably monolithically formed with the other elements. The 5 me~er moves into and out of the well as it de~lects toward and away ~, 6 f~om thf sub8tra~e. ~ -7 ~ ~
-,:
8 In one embodiment, ~he control electrode i9 a region of the ;
~! 9 substrate itself and the control si,gnal i9 applied between the ~, 10 subst~ate region and the member. The facilit~y for applying the input 11 signal includes a conduc~ve input path and a condu,~ive output path 12 oppo3itely con~ected to ~e member so that the input 8i~al pa~ses 13 through the member. More specifically, ~e control si,grlal may be ~ ., 14 applied between the substrate region and one of the co~duc1;ive paths ~, 15 connected to the member. In this em'bodiment, the ~ubstrate region 16 may be grounded and the capacitor may be efFec1;ively in ~hunt wi~h ., ~, . .
17 the input ~ignal.
18 !; ~-~
19 In another embodiment, an elec~;riciallyir~sulative dielectric ~; 20 layer on the substrate ~upport8 the control electrode on, and insulate~
.~1 21 it ~om, the ~ubst~te. The control signal i~ applied between the '~r ~" 15 : ' .. ~.
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control electrode and the mem~er. The facilities for applying the `` 2 ~nput ~ignal include a conduc~ve input path co~nected to the mernbers 3 and a conductive output path spaced fi~om the member in the :il 4 direction of it~ de~ec~on. The output path i8 supported on and ,d,~ 5 i~ulated from the substrate 80 that the input signal i8 applied by the ~' 6 member to the output path acting a~ one plate of the capacitor. The 7 con~ol signal may be applied between the co~trol electrode and the .. , ,~
8 conductive input path. In t~is em3~odiment, the capacitor may be put 9 effe~ively in series with the input signal.
~j 10 11 l~rpically, the input signal i8 time-varying, while the control .~ 12 8ignal has a f~equency substantially less than that of the input 13 signal. Preferably, the co~trol aignal i9 substantially no~-~ne-14 varying. Indeed, the fre~uency of the input 8igD.al i9 prefer~ly 15 suf~icie}ltly high 90 with respect to the resonant ~equency of the 16 member 90 that the member cannot defiect ~ responae thereto and i9 ~, 17 es~enS;ially '~ d" to the input 8ig~1al a~ far as def~ectio~ i~
"3 18 coIIGerned. Co~trariwi~e, the frequency of the co~trol 8ig~
19 sl~fficienS~ly low 90 that the beam deflects in 8y~1ChrO~119m there~ith.

20 A.lso preferably, the input Bigllal and the con~l 3igIlal are 21 supenmposed.

~ J ..
., ' :,1 . .s The amount, fi~equency, mode and other characteristic~ of 2 member movement may be selectively adjusted. Ad~tment may be 3 achieved, for e~ample, by selective removal of materi~l from the 4 member (to decrea~e its mag3 and area) or firom the member (to alter 5 its compliance). Such remov~l may be e~fected by the use of 6 concentrated light energ~, for e~ample ~om a laser trimmer.

8 The capacitor of the presenLt in~e~tion may be included as aD
9 element of or a porlion of any of the device listed in the paragraph preceding thi~ SU~AR~ 80 that the impedance and imped~nce-11 related characteri~tic~ of the devices may be selectively al~ered.

. ! 12 13 IDI a broader aspect, the present invention contemplates a 14 microminiature, monolit~ic device for affecting an electrical input ~ al in response to a co~trol 8ignal. The device includes a substrate 16 and a movable member which normally occupies a first position. In 17 the fir~t position, the member af~ect~ the ~put 8ignal in a first mode.
;. ~i 18 When ~he member i8 not in the first po~ition it af~ects the input 19 6ig~al in a second mode. Facili~es mount the member ~pa~d ~om ~; 20 tlhe 8nb8tr. te for movement toward aIld away firom the ~ubstrate.
21 The mounting facilities ~t~re energy thereill when the member move .:`1 l, 1 7 , ., - .

: ' .~

out of the first position. The stored energy biases the member toward 2 the first position.
;~ 3 . -~4 The input signal is applied to the device ~nd a co~trol 8igIlal iS : :~
applied to the member. Facilitie~ respond to the control signal to selecl;ively move the member out of its fir~t position to co~sequently - 7 ~electi~ely alter the mode ~n which the member af3Eects the i:nput 8 si~al.
, . . .
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. ~, In preferred embodiments of the broader aspect, the member is ~ -11 electric~lly conducl;ive and the application of the colltrol signal 12 thereto produce~ an electrostatic field acting thereon. The field 13 moves the member out of the first position.
i'il .~i 14 ~i~
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16 A specific device re8ulting :~om the broader a~pects of the ~3 "J 16 illvention is a v2riable CapaCitor9 i:n which the mo~able member i9 one :.
17 plate of the capac~tor~ movement of the member altering the :~ 18 capacitaDce of the capacitor. Irhe illpUt ~ignal a~d the control ~
19 may both be applied to the member. l~e path taken by the input :~ 20 ~ig~l may be in parallel or ~ 8erie~ with the alter~ble capacitance. :
21 Prefersbly, moveme~t of l;he capacitor is tow~rd the gll~8$rate to ~ :

~ 18 ::s~

s i~crease the capacitance ~om a rnirlimum value, although moYement 2 may be away ~om the sub3trate to decrease the capa~tance ~om a `Y 3 manmum value.
~ 4 :`
Another specific dev~ce resul~g ~om the broader aspects of ~! 6 the invention is a waveguide. I~ the waveguide, the movable member , . .
7 fonns a coplanar portion of the interior surface of tha waveg~ude in :
- 8 the first position thereo Moveme~ of the member out of the fir5t 9 position i5 away from the ~ubstrate and f~om the waveguide wall.
,, .
Such movemerlt effectively decreaises the crosR-sectio~ of the 11 waveguide along a line generally parallel to the li~e of moveme~t of .. , . ~
` 12 the member.
,~JI 13 ,.lj 14 The input signal may be time vary~g, and the member may be ' '~!
i`h~ 15 v~gly deflected with respect to time. I~e frequency of the 16 deflection of t~e member is, in preferred embodiments, independen~ of 17 the ~e~ue~cy of the input ~ al, and is preferably smaller th~n the i~J - ~ ~-18 ~equency ofthe input signal. Anon-linear capacitorre3ults when 19 the member i9 de~lecteid at a firequency which ia ~ubsta~ltially the ~ame as the ~equency of the input ~ig~al. T~is de~lectio~ m~y be ;
.

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, :
, 5~, 1 about or with respect to a first, normal position of the member which 2 i9 set by the control sig~

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BRrEF DESC: EUPIION OF I~IE DRAWING

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3 Figur~ 1 i8 a generalized, sect;ioned side view of a variable 4 electrical capscitor in accordance with the pr~nciple~ of the present 5 inverltion, the capacitor being coDs~ituted of aIl elas~mer type 0I
i 6 DMD SLM;

7 E~gure 2 is a ge~eralized, sectioned side view of two types of c 8 vanable elec~ical capacitors iD accordance with the princ:iples of the ~,'! 9 presentinven~on, the capacitors beîng constituted oft~o membrane type of DMD SLM~;
11 E'igurs 3 ia a ~chematic depict;ion of a DMD SLM used as a `"? 12 variable capacitor according to the present inven~oII and electrically ., 13 connected to operate a~ a shunt or parallel capacitance;
14 E~gure 4 is a achem~c depiction of a DMD ~3LM used as a 16 vanable eapacitor accordiIlg to the pre~ent inve~1~on and electrically 16 coDnected to operate as 8 series capacita~ce;
17 ~i$11~ ~; i8 a gr~ph of a colltrol ~ignal and a~ input signal 18 ver8u8 time which are applied to the variable capa~tors of Figures 3 19 and 4; ;
l~gllre 6 i8 a ge~eralized top view of a porlian of a me~brane 21 type of variable capacitor, 8imilar to that ~hown at the laft in Figure ::
... - ~ .

'` . ': :, :' : , ~' ' . ' . ' ~ , ' ; ~ :
2, and in Figures 4, and 7-9, and 18-25 which includes ~tructure, to 2 operate as a series ~a~iable capac~tor according to the pnnciples of 3 the present invention as described with reference to Figure 4.
4 E'igure 7 is a generalized, sectioned ~ide view of a membrane 5 type of variable capacitor, taken generally along line 7-7 in Figure 8, 6 which is similar to those shown in Figures 2~, 6, 9 and 18-25, which 7 utiL;zes spacers 5imilal' to tho~e shown in Figures 2-4 rather the posts 8 shown in Figures 9 a~d 187 the capacitor including facilitie~ for 9 en~uring~ that a ~ignificant por~ion of the capacitor remai~s planar rath~r than deforming curvelinearly as in E'igures 2~, 6, 20 and 11 25(b);
12 Figure 8 is a generalized top view of the membrane type of `.',!1 ' 13 vsriable capacitor deplcted iIl Figure 7, porlions of the capacitor being 14 broken away to better illustrate the constil;uent elements thereof; ~ ~ :
1~ FigurQ 9 includes gener~lized, sectioned side view a membrane ~ ~ : , 18 type of DMD SLM u~ed a va~iable capaci.tors Dl a manner 3imilar to 17 the use of the DMD SLM'8 depioted i~l Figures 2 and 7, the 18 membrane thereof being supported by posts rather thaD the ~pacers I
19 ofEigures2and7,thedeforInedme~ranebeingmaintainedplanar ~`I 20 by appropria~e facilil;ie~

E igure 10 is a generalized, ~ectioned side view of a cantilever-2 beam type of DMD SLM which i~ used as a vanable electrical i 3 capac~tor;
4 E'igure 11 is a generalized, sectioned side view of a ca~lever-5 bea~a ~pe of DMD SLM used as a v~iable capacitor irl a manner 6 similar to the u~e of the DMD SLM depicted in Fig~e 10, the beams 7 and the hinges thereof being supported by conductive post~ rather 8 than the spacers shown in Eigare 10;
9 E~gure 12 is a generalized, ~ectioned side ~riew of a can~lever-10 beam type of variable capacitor similar to thoae ~hown in Figure~ 10 11 and 11 which utili~es ~sulative spacers similar to those shown in 12 Figure 7 rather than the poata shown in Figures 3 and 4; :
13 Figure 13 includes generalized top views of two dii~erent -:
14 ca~lever-beam types of DMD SLl~a'8 used as variable capacitors, the v~ews of Figures 10 and 12 being taken generally along line 10,12-,,;1 . . .:
:;i 16 1û,12 in Fig~re 13; - .
17 E gure 14 i~cludes generalized top view~ of four different i ~ 18 tors~on-beam types of DMD SLM~8 used as vanable capacitors;
-. . 19 Figure lB is agenerali2ed top ~view of a~le~cure-be~mtgp~ of ;
.` 20 DMD SLM used as a v~iable capa~tor, the views of Fi~ures 16 and 21 17 being taken generally along line 16,17-16,17 iD Figure 15;

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Figures 16 a~d 17 are generalized, sec~oned side Yiews of a 2 ~e2~ure-beam type of DMD SLM, taken generally along line 16,17-i . 3 16,17 in Figure 15, which respectively depict a variable capacitor ~ ~;
4 according to the preqent invention nd having a member in a normal -; 5 position (Figure 16) and the member in a poBition resulting firom it~
~`^ 6 attraction toward a control electrode (Fig~lre 17);
7 Figu~s 18(a) and 18(b) are, respectively, a side, sectioned 8 elevation and a plan view of a membrane-type of DMD SL~ used as .. ` 9 a switch for a tran~mission line;
` ';
-, 10 E ig~ 19 is a side, sectioned view of a mem~ e type of ,~ 11 DMD SLM used as a variable capacitor arld utilizing both a 12 corlducti~re post (of the type showIl in Eigure 9) and an insulative ;~ 13 spacer (of the type shown in Figure 7) to sl:lpport the membraIle;
~: j 14 Figure 20 depicts, re~pec~vely, a sitLe, seclioned view and plan :
15 v~ews of a plurality of membrane t~pes of DMD SLM's u~ed as ~3 16 vana~le impedance 8trip tra~smis3ion li~e~

, ~ 18 Figure 21 depicts general:ized plan v~ews of four tu~able, ` 19 f~ueY~ agile couplers eachutili~gmultiple DMD SLM'8 20 accordingto the p~ciple~ ofthe present~Ilvention;

.~2 ~ .
.' i ., :,,: , Figure 22 generally shows a perspective view of a ~equency-2 agile and pattern-agile patch antenna which coIltain6 plural DMD
3 SLM~s according to the principles of the present invenlion;
4 EYgllre 28 i9 a generalized side, sectioned new and plan view of a FIN line containing arrays of DMD SL~s operating a~ variable 6 capacitors for tun~ngthereof;
7 Figll~ 24 i9 a generalized perspective view of an array of 8 variable capacitor~ compr~sing D~ SLM'~ pursuant to the present 9 invention whichis usedin a waveg~ide-to-micro6trip tran~ition; and : -.~
0 Figll9~ 2~i i8 an end, perspèctive view aad a m~ified view of 11 a por~on thereof, both illustrating the u6e OI multiple DMD SLM's ~ ~ :
,1 12 operat;ing as movable members for alte ing the elec~;rical `1 13 characteristic~ of a waveguide into which the members are 14 incorporated.
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DE~ILED DESCRIPTION
3 The present inYention relates to m~crom~niature, monolithic 4 d~vices 40, 50, 60, 70, 80 and 160 of the types shown respecti~ely in Figures 2~ and 6-9; ~?igurei~ 10-13; E'igure 14; Figuxes 15-17; Figure 8 6. and ESgure 19. The dev~ces 40, 60, 60 and 70 are varisble elec'crical 7 capacitors; the device 80 is an electrical or optical sw~1;ch~ The 8 devices 40, 5û, 60, 70 and 80 are constituted of elemental DMD SLM's ~ ~ :
9 40', 50', 60', 70' and 80' modified or utilized a~ descnbed below, and electrically operated in a vanety of w~ys, for esa~ple, as generally 11 illustrated in Figure~ 3 and 4. The present iIn~ention al80 relates to ;
12 ulilizing the capacitors 40, 50, 60, 70, 80 arld 160 in apparatus a~
13 illustrated in Figures 20-25.

Figures 2-17, are ge~elalized depicl;ions of a variety of 16 elemental DMD SLM'8 40', 50', 60' a~d 70', the structure~ of which 17 ~e~e a~ the ba~ic building blocks for the variable capacitor~ 40, ~0, ;
18 60 and 70 of the present inYentioll. Eigure 1 depicts n elemental , ~, 19 DMD SLM 30' of a type ~lOt as coIlverlien~y adiapted to be used as a variable capacitor 30 according to the prese~ ventio~, but which 21 could be 80 adapted, if desired. Fig~re l i8, ill aIly eYe~ u~ed a~
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illustration of some principles of the present invention as em~odied in 2 Figures 2-25.

4 Figure 1 depicts an elastomer type of elemental DMD SLM 30' which includes an relatively thick elastomeric layer 31 carrging a 6 defo~able, rela~velyt~ deposited metal layer ormembraDe 32.
7 Where the DMD 30' i8 used as 8uch, the metal layer 32 i9 highly 8 light-relqective. The layer membralle 31 and 32 are depo~ited on a 9 silicon or other suitable substrate 33 atop an addres~ing circuit, only lû generally indicated at 3~, by ~tandard hybrid integrated circuit MOS .
11 CMOS, etc. processing techniques. The circuit 35 may be formed in 12 and/or on the subst;rate 33 arld illcludes sp~ced control or address , ~, .
.~ 13 electrodes 36a. As in otherDMD SLM's 9L0', 50', 60', and 70', ii 14 although the control electrode~ 3ffa are de]picted a~ residing on the top ~urface of the substrate 33, they may be '~uried" or integrated in .1 16 the ~ubstrate 33 ~ independent conducti~re path~ or a~ appropriately :~
17 doped regio~. The elastomeIic layer 31 ha~ 8 normal or first , ~ 18 thic~ne~s T which maintaiD~ the metal layer or mem~rane 32 a 19 no~al, fir~t di~tance D awa~ om the top of the subst~ate 33 and a .~ 20 dista~ce d above the co~trol electrodea 36a ca~ied thereby (D and d 'i`~'A 21 beillg equal if the elec~odes 36a are buned~, DependiIlgon the :i.,. ,~
., .~ . , ii 27 : .x ' ~ , .

matenals of the layers and membranes 31 and 32, the substrate 33 2 and the control electrodes 36a, as well as on the nature of the 3 addre~sing circ lit 36, the electrodes 36a may be ~sulatively spaced 4 from the substrate 33 by an eleckically insulative layer 37, which may be an o~ide of the matenial of the substrate 33 or other oz~de or 6 insulative material.
8 When a control electrode 38a is energized 80 that it and the 9 immediately ~upe2~acent segment 38 of the metal layer or membrane 32 ha~e impo~ed thereon sufflcie~y large potentials of opposite 11 polarity --whether tbis is achieved by the addre~sing circuit 3~
^, h~ 12 af~ecting the control electrode 36a or otherwise- the electrostatic 13 force between the segment 38 and t;he elect:rode 36a may attract (or 14 repel) the segment 38 toward (or away from) the electrode 36a. This 15 attraction (or repul~ion) moves or curvili~early de:aects the segment 16 38 toward (or away f~Dm) the electrode 36a~ thereby decrea~ing (or 17 increasing~ the thic~ne~e~ of th~ ~tervening m~ter~al of the 18 elastomeric layer 31 to D, and d, as ~hown i~ Eigure 1. Alternatively, I
~:i 19 pote~ of tlle ~ame polarity could be applied to both the ~ontrol 20 ele~ode 36a and the supe~acent segment 38 to produce an .

:~ 28 :;.
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i ', 1 electrostatic repulsion force therebetween which will increa~e, rather .. 2 than decrease, the distances D and d.
,~ 3 4 Thu8, depending on the state, energized or deenergized, of the :~
~i ~ control electrode~ 36a and on the polarity of each elec~odes 36a and6 it~ related ~egment 38, the thicl~ness of the elastomer 31 is : ;:
7 dimi~lished (or~ncreased) o-rer the ele~ode 36a andi~ increased or .~. 8 diminished between adjacent electrodes 36a. VVhen the electrodes ~ii :j 9 36a are deenergized and the layers or membranes 31 a~d 32 are in 10 their no~al, first positions. The firE,t position of the met~l layer or ii.' 11 rnemb,rane 32 i~ denotedby a dashedline 39. When the membranes 12 31 and 32 are deformed by ~ at;tracti~e electro~tatic field out of the 13 firE,t position 39, potential energy i8 ~tored therein. llle s~red ;
i~ 14 potential energy tend~ to retu~ the membranes 31 and 32 to the~r 1~ no~nal, first generally planar pO9itiO~1 39. When an energized elec~
16 trode 36a is deener~zed, the energy stored in ~egment 38 aIld the immediately suIToullding por~ion~ of the membranes 31 a~d 32 to -18 no~al planar~ty.

2û ~ l~he ~urface varia~o~s of the metal layer 32 e~ected by . ~ 21 ~elective e~ergiza~o~ of the co~ltrol electrode~ 36a may be used to .~
~.", 29 ~ ~ ~
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modulate incident light in amplitude or phase when the elemental . 2 DMD 30' is used as 8uch.
:~ :
4 Althou~h impressing voltages of the s~me polanty on the ~ 5 electrodes 36a and the~r related segment~ 38 is efEective to move the 7~ 6 segment~ 38 out of their first position~ 39 either toward or away ~om - 7 the colltrol electrodes 36a, the remainder of the description will focus 8 on impressed voltages of differellt polaritie~ which effect movement of :~ 9 the segment~ 38 ofthe membrane~ 32 (ortheirfimctional .1, 10 counterparts) towardt~e electrodes 36a. Further, a~ will be 11 apparent, when a voltage i8 impressed on one element, say a ~egment 12 38, a atl;ractive voltage of an oppo~ite pol~rity may either be ta) 13 i~duced on the corresponding other elemeDlt, here a control electrode 14 36a, OI (b) directly applied or impressed vii~ independent agency 15 ( uch as the addres~ng circuit 35) on the other element. The ~; 16 voltages --attractive or repulsive--on each ~egment 38 ~nd it3 ... ~ 17 elec~ode 36a may be efEeeted as appropriate by the addres~ g circuit -,.,.:~ !
19 :~
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In Figure 1, an output electrode 36b and a re~pective 21 ~uperjacent segmellt 38 of the metal layer 32 may be viewed as the : .~
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.

'i ' 'i plate~ of a variable, parallel plate capacitor 30. Specifically, the 2 ~egment 38 i~ the movable plate or member and the electrode 36b i~
3 the ~tationary plate. The electrode 36b may be adjacent to its 4 com~ponding con~ol electrode 36a o~ the sub~trate 33, i~q shown i Eigure 1, wherein the electrode 36b i~ behind the electrode 36a into 6 the plane ofthe Figure. The dielect;ric bet~veen the rela~vely 7 movable capacitor plates 36b ant 38 i8 the elastomer 31.
, 8 Alternatively, the fi~ction of the electrode 36b may be performed by 9 the ~ubstrate 33, if it i~ s~iciently conductive, or by a conduc~ve ~egioIl formed therein when the substrate 33 iB not sufficiently ~ ~:
11 conductiYe. A~ describedbelow, the electrodè 36b maybe absent and ~ ~ :
,.i :
12 the co~t~ol electrode 35a may ~is~ume its fi~ctio~. Sincei the distance ;:
i 13 between the capacitor plates 36b, 38 is adjnstable, the capacitor 30 is ~l 14 var~able. The foregoing assumes that elect~ical control 9ig~1alS
., 15 applied to the control electrodes 36a and ~le 6egments 38 of the ....
16 metal membrane 32 for adju~ g the capacltance of the capacitor 30 ;;
~is 17 may be applied independently of and without sffiec~ing ~ny input .~i ~- '. 18 electrical signal w~ich i9 intended to be a~ected only by the capacitor I ~ .
:~, . ...
19 30 (i.e., the capa~tor ~6b, 38) arld vice versa. Tbch~iques for ~'. ' applying these ~ignals to the varisble capacitors 40, 50, 60 and 70 in 21 ~i~ manner are de~cnbed below. Suf~ice it here l;o note that if each segment 38 of the metal membraDe 32 i9 to function as the movable 2 plate of a variable parallel plate capacitor independently of its 3 neighbo~g variable capacitors 30, adjacent segments 38 should be 4 electrically isolated, for e2ample by rendenng the metal layer 32 discontinuous in regions thereof supe~acen~ to the ~paces between 6 each pair of electrodes 36a and 36b. If the electrode pairs 36a, 36b 7 reside in an array thereof, a colTespondi~lg array of variable 8 capacitors 30 may be formed by a gnd of discontin~uties (not shown) 9 ill the metal :layer 32. It should be further noted that the individual ~ ~;
aegments 38 of the metal layer 32 of the a~ay of vanable capacitors 11 30, may be viewed in a macro ~ense to, represeIlt a "~u~face" having 12 dist;~ibuted variable capacitance as descnbed later, this "s~ace" may 13 cons~tute a portion of the surfsce of a vanety of apparatus, such as a 14 traIlsmission line, a coupler, an antenna, a FIN line or a wave~de.:~
.,ij ~
16 Thus, Figure 1 illustrates the elementa3i DMD SLM 30' 17 for~nerly used to modulate light fimctionin~ as a v~riable capaci~or 30 , .i 18 and, as it were, a~ a device having a member (the segment 38) whiGh 19 i8 rela~vely movable with re~pect to a 8tatiol~ary member (the , ~ .
!20 eleetrodes 36 andlor the ~llb8trate 33).
;. 21 , .
.: 32 : ., .~,,, :

Continuing to refer to Figure 1, as the electrical control signals 2 are applied to the control electrodes 36a and the segment 38, the 3 segment or movable capacitor plate 38 at the left and it~ output 4 electrode or stationary capacitor plate 36b form a capa~tor 30 indepeIIdent of other adjacent capacitor~ 30. An i~put ~ignal may be i 6 applied to the ~egment 38 by an input co~ductor 38i wbich i8 , .
`~ 7 electrically con~uou~ with one e~tremity of the ~egment 38. If the 8 capacitor 30 (or 36b, 38) i8 to affect the input 8igIlal on the conductor .. 1 9 38i by being in parallel therewith, an output conductor 380p ii .
0 ele~trically cont~uous with another opposed e~ctremit~y of the ~egment 11 38 maybe provided. The input sig~al will1~e a~ected bythe 12 capacitor 30 (or 36b,38) a3 it traverses the Elegment 38 in a manner 13 determined bythe capacitance ofthe capacitor 30, w~ich i9 14 determined by the distance between the segment 38 and the electrode 15 36b (aIld ultimately by the polantie~ of and the difEerence between 16 the voltage~ o~ the segment 38 ~nd the control electrode 36a). This 17 fi~ctionofthe capacitor 30, whichi~illuetrated schemalicallyin :
. ...................................................................... .
.~ 18 Figure 1(a), may require grou~ding the elec~;rode 36~ a~ ~hown at 19 36g. The fianction of ~he electrode 36b may be performed by the ~ :
20 subs~ate 33 orby a conductive regio~ormediIl the substrate 33, ~` 21 which may, if nece~aary, be grounded.

~ . . . .

.,"
.... .
;, If the capacitor 30 (36b,38) is to se~ially a~ect an i~put sign~
2 on conductor 38i, an output conductor 3609 electrically continuous 3 with eleci;rode 36b is provided (the conductor 380p and the ground 36g4 may be eliminated). Thi8 functio~ of the capacitor 30 i8 i~lu~t~ated ~:
schematically ~n Figure 1(b). :
7 Figure 2 illu~trates adjacent elemental DMD'~ 40' of the 8 membrane type each used as a vanable capacitance 40. One pos~ible type of DMD 40'-- which is somewhat inco~venient to manufacture by ;. 10 MOS, CMOS and other tech~iques~ i shown at the righ~ a~d ;1 .
11 comprises avana~t of Figure 1, po~essing a thin polymermembrane 12 41 covered with a t~in defor~ble membrane layer of metal 42. In a ,:~
13 more preferred form, the DMD 40' includes only a thin, deformable, 14 self-supporting, thin metal layer or membrane 42 a~ shown at the lePc -`5l 15 i~ Figure 2; the polymer membrane 41 i~ eliminated. The metal layer or mem~rane 42 (and the polymer membrane 41, if present) i~
, i.~
:i~. 17 supported above a gub~l;rate 43, 9imilar to the suh~trate 33, by ~i 18 spacer~ 44. In l~ypical DMD's 4û' of thi8 type, the spacers 44 lie on an 1~ orthogonal grid. An addre3~ g cirGuit, gellerally shown at 46 and ~`1 20 i~cluding a co~trol elecl;rbde 46a, underlies the metal meml~ e 42 . ,.
21 ~nthin each area defined by the g~d of ~pacers 44. The addres~
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circu~ts 45 and their electrode~ 46a may be similar to their 2 counterpartq 35 and 36a ~ Figure 1. To avoid clutter, output 3 electrodes 46b physically similar to the electrodes 36b are not ~hown.
4 Where required, the electrodes 46a, 46b may be electrically insulstive from the substrate 43 by an insulative layer 47, similar to the layer 6 37 in Figure 1. The segment 48 of each met~l layer 42 directly "1 ~
7 superjacent to its electrodes 46a snd 46b m~y be attracted toward (or 8 repulsed away from) such electrodes 46a a~d 46b by application of 9 an appropriate poten~al dif~erence betweenthe segment 48 a~d the ,,~
i;~ 10 electrode 46a. Thi~ at1;rac~on (or repulsioll) c~e~rly moYes or . ~
.~ 11 de~ect~q the qegment 48 by simultaneously deforming the metal ~ ~:
',~ 12 membrane 42 out of its first position or normal plan~3r con~igura~on, ::
./ 13 indicated by the broken line 49.
. ,~
'.''J, 14 1~ As with the elemental DMD 30', the elementalDMD 40' may 16 be viewed, and u~ed, as a variable capacitor 40. The dielectric 17 between the 8tationa~ plate --the electrode 46b-- and the movable 18 plate -the metal membrane 4~-- may be air or another e2~pedient . 19 medium, rather than tho els~tomer 31. AB with the capacitor 30, if .. ~ . . ~ , ;~, 20 the individual ~egments 48 of the metal membra~e 42 are to fimct;io~
`.~ 21 a~ i~dependent movable plates of independe~t vanable capa~tors 40, :

~, 3 5 .
.

.,", the segments 48 should be electrically isolated from each other as by 2 fo~ning a pattern of discontinuitie~ (not shown) in the metal layer 42 3 congruently with the pattern of space~ 44.
',3 4 :
~i 5 A~ no~ed earlier, ~n some prior elemen~al DMD's 40', the 6 ~pacers 44 are in a grid ~o that ener~ization of a control elec1;rode 46a `. 7 results in configuring the correspollding segment 48 of the membra~e8 42 in a spherical or other curvili~ear manner. Achieving this A~
9 cur~ilinear configura1;ion is not necessary if the ~egments 48 are to ;.'~ 10 act as the movable or deflectable plate3 of air-gap, van~ble capacitors 11 4û. Indeed, producing the c~ear configuration may render . 12 analysi~ of tlhe capacitance of the re~ g capacitor 40 (46b,48) 13 rather difficult and, more importantly, may re~e that the potential 14 , di~erence acros~ each segment 48 and its coITesponding cont~ol .~ 15 electrode 46a be unrea~onably high. A~ discu~ed iR more detail 16 belo~, each capacitor 40 preferably ulilize~ a pair of pasallel spacers . 17 44 a~d I~Ot a bo~-like gIid thereof. In tl~ vay, each segment 4~ of 18 the membrane 42 i8 ~upported only at two diametrically oppo~ite 19 side~ thereof, not completely around the periphery of the ~egment 48.
A~ a co~seq~ence, lower voltages a~c required to achieve a gi ren 21 deflection of the 8egmeIlt8 48 of the rnembrane 42 and, hence, a given ~ :

.~ 36 , ~., .
;-,, . ~ .
~;' .c-'~

capacitance value. - Discontinuities in the membrane 42 to render the 2 individual capacitor~ 40 independent of each other may be congruent 3 with the ~pacer~ 44.
ti 4 Turning now to Figures 3-6, the operatiorl OI the elemental . ~.
- 6 DMD 40' of the left porl;ion ot`Eigure 2 used as a variable capacitor :! 7 40 is described. As will be seen, the pnnciples illustrated by the~e 8 Figu~es are applicable to the other elemental DMD's. The following .", ~ ~
9 description assumes that membrane 42 i8 electrically independent of .. . .
its neighboring membra~e~ 42 in the aIray of elemental DMD's 40' 90 11 that each capacitor 40 i8 electrically indepeIIdent of its neighboring 12 capacitors 40 in the capacitor array. VVhethler such independence is 13 achieved by fotm~ng the afore~oted disconl~luities (~ot shown) in the 14 metal layer 42 or otherwise -as b~r appropriate energization of the 15 electrodes 46 orby elect~ical i~olation techniques~ i8 unimportantto 16 the present in~lell~ion.
-17 ID E'igur~ 3, $he norm 1 po~i1;io~ of l;he membrane 4~
18 depicted, while the position thereof dur~g atSraction or deflec~on 19 toward the electrode 46a i~ ~howll by a broke~ 3ine 100. (The li~e 100 would be bo~1ved upwardly if the membrane 4~ were repul~ed ~ ~ .
', 21 away f~om the conl;rol ele~trode 46a and the outpug electrode 46b).

~ 3 7 .
"., .'".' ! `. .

Figure 3 illustrates the capacitor 40 in a para~lel or shu~t connection (see l80 Figure 1(a)), and the re~erence numer~l 40P is used to 3 de~ ate the capacitor 40 connected in this manner. As e~plsined 4 below, the insula1ive layer 47 of Figure 2 m.ay ~ot be needed in the 5 embodiment of Figure 3. Specifica~ly, as will ba seen, the stalionary ,. .
6 plate of the capacitor 40P --here, either the substrate 43 or the 7 electrode 46b residerlt on such substrate 43-- i8 grounded, aa shown , , `.. 8 at 101, 30 that there i8 a capacita~ce-to-ground betwee~ it and the 3 9 movable or deflectable membrane 42 ofthe capacitor 40P. Avariable `~ 10 control ~ignal 102 is applied by a control signal source 104 to the ~.., i 11 mem~ra~e 42, as indicated by the path 106 between the source 104 ~`j 12 and an input 108 which is schema~cally ~hown as coDIlected to the .~ 13 layer 42 at 110. Ihe source 104 may al~o be connected to ground at l 14 112.

::`
16 The variable control sigllal 102 may be a '~ow fi~equeIlcy"
;~ 17 voltage, Vc, w~lich may be a DC voltage, the msgnitude and/or duty 18 cycle of 7vhich i9 variable. A~ u~ed herein, a 'low ~equency" voltage .. ~ 19 means a voltage hav~ng a firequellcy ~w~ich, with re~pect to the : ;~
20 reso~ant ~equency of ~e movable portion of the membra~e 42 21 supported betwee~ the spacers 44, i.e., the segment 48 i8 su~iciently : ~ :
3~

!

r~

low ~o that the membrane 42 of a capacitor 40P to which the control 2 si~l 102 is applied, is able to nearly in~tantaneously move or 3 de~ect substan~iallyin syn~onism therewith If the 8ignal 102 is :~
4 dc, (~equency=0) the membrane 42 rema~ stationary and the variable capacitor 40P is con~tant. If the control aigIlal 102 is time- ~;
~' 6 varying and, the membrane 42 moves in 8ynChI'Orli8m therewith, the .
.... 7 capac~tor 40P is var~able time.
., 9 Specifically, when a control voltage 102 is applied between the `, 10 membrane 42 and either the underlying portion of the aubstrate 43 11 (ac1ing as a co~trol electrode) or the conl;rol electrode 46a, an -~ 12 eleclro~tatic field i9 produced Lll the space between the membrane 42 ,. . .
~;, 13 and the ~ubstrate 43 or the electrode 46a. If the control ~ignal 102 i~
. ! :
j 14 a DC voltage as shown ~ Figure 5, the re~ultant electro~ ic field i9 15 non-time-v~g, resulti~g iD the membrane 42 being moved or ~; 16 def~ected toward (or away from) the ~ub~trate 43 or the electrode 46a t j~; 17 out of its no~nal, first position a~ a funcl;io~ of t~ magDitude of the ~;:.. , 18 voltage. Such movement or de~lection decreases (or iIlcre~ses) the ` 19 distance between tlle membrarle 42 and the ~ubstrate 43 or the :
.. ~ 2û elect;rode46s. Since the capaci~ce of aparallelplate capacitoris 21 iIIv~rsely proportio~al to the dist~ce betwee~ the plates 42, 43 or 39 ~;

~j ~
~, 1 ~;

:
42,46a thereof, this decrease (or increase) in dist nce increases (or 2 decreases) the capacitance of the eapacitor 40P. Removal OI the .. 3 control signal 102 peImits the mechanical energy stored in the , .
' 4 membrane 42 (as a result of its deforma~on and del~ection) to retu~
i~ 5 the membra~e 42 to the normal, plan~r position, which repre~ents ,r~ 6 the minimum (or ma2~num~ capaci~ance of the cspa~tor 40P, since 7 the sep~ration between the plates 42 and 43, or 42 and 46a thereof is ~- 8 at its maximum ~or m~nimum). Thus, the capacitance of the capacitor . 9 40P is a fimction of the control ~ al 102. If the polarity of the 10 voltages o~ the membrane 42 and on the substrate 43 or on the , . .
,!' 11 electrode 46a is the same, aIl ~creasing ~oltage di~erence moves the : :
12 membrane 42 out of its ma~imum capacitance position to one whereat -' 13 the capacitor 40P has a lower capacitance.

1~ In view of the resonan~fi~equency-detenniI~ing and other ; :~
16 mechanical characteristics of the membrane 4~ -~haracteristics such ;~
17 as, withoutlimitation, the 9iZel, areal cor~ationa~dmas~ oftJle 18 meral)rane 42; the ducl;ili* and thickness of 1 he membra~e 42; the 19 tlbickness and the ela~tic mod7~ nd/or ~pnng constant of the ~j 20 membrane 42, and the man~er and amount of membrane 42 support - ~ ~ -21 -there i8 a ra~ge of ~equerlcies be~g w~th zero (0 ~equency ;:

. .

~ :

being DC) which v~ill permit the membrane 42 to move or deflect 2 sub~tantially in synchronism therewith. The foregoing is generally 3 true for a low ~equency voltage having practically any wavefo~.
4 Those skilled iD the art will be able to ea9ily determine what 5 constitutes a 'low frequency" co~trol voltage 102 for a given 6 membrane 42. Inpreferred embodiments, the control BigIlal 102 i~
7 either a dc voltage the amplitude of which i~ selectively variable or a 8 dc voltage vvith a constant amplitude, the duty cycle ("ol~/of~ time") of 9 whichis selectivelyvanable. The~e types of control sig~ 102 result 10 in the capadtor 40P effectively functioning a8 a variable, linear 11 capacitor. If the colltrol voltsge 102 i8 lime varying at fi~eque~
12 sui~iciently low to pe~it the membrane 42 to de~lect alld "undeflect"
13 in synchronism there~1vith, the capacitor 40:P e~ec~vely funclion~ as a 14 vaxiable capacqtor.
16 The variable capacitor 40P i8 intellded to affiect an ~put 8igD
17 114. The ~put sig~al 114, w~ich is a ~e-~arying voltage, . - ~
18 preferably ha8, relstiYe to the control ~ al 102, a ' high firequency."
19 For purpo~es hereof, a "~igh f~eque~cy" input ~ignal 114 meaIIa a 20 ~ignal ha~ing a ~equency ~o high that~ oon~idering the re~onan~
21 f~eqllency-determilling mechanical and other characteri~tic~ of the ` ~ 41 ,! .~
"'X
.'`.,. .~

:

membrane 42, as de~ibed above, the membrane 42 can~ot move or 2 deflect in response thereto in any 9igIlifiCaDt manner. That is, in , 3 simplistic term9, the mechanical inertia of the membraIle 42 i9 too 4 high, and the changes in the input sig~al 114 with time ~e too rapid 5 for the membrane 42 to respond thereto. In essence, the membrane 6 42 cannot "se~" the high frequency input signal 114.

8 The input signal 114, preferably in the form of a high 9 f~equen~r voltage, V, as diacusaed above, i9 applied to the input 108 and to the membrane 42 from a 80urce 116 via a path 118. An 11 output 120 is comlected to the membrane 42 ~t 122. Ihe source 116 12 is grolanded at 112. In effect, the control ~ignal 102 and the illpUt 13 8ig~1al 114 may be superimposed at the input 108 and simultaneously 14 applied to the membrane 42, a8 shown i~ Figure 6.

16 A85U~g that the outp~t 120 i~ ~pplied to alld utilized by a ; :
.3 17 utilizatioll circuit (not ~ho~) or othe~wise, the low f~eque~c3r con~d 18 voltage 102 adju~ts the di~tance between the segme~t 48 of the 19 membra~e 42 and the ~strate 43 or the output electrode 46b ,?~ 20 the~eby adjus~ng the capacit~ce~ grou~d of the capacitor 40P the 21 plate~ of w~ re the membrane 42 (movable plate) and the ''` , :, :~:
: 4 2 , .,~" ~' ~ .
:.
`,' , : : :

`

:
substrate 43 or the electrode 46b (stationary plate). The adjusted 2 capacit nce-to-ground ai~ects the impedance of the path 118-10842-3 120 and, accordingly, the input signal 114. The input signal 114 has - 4 no effect on the deflection of the meml~rane 42 and, accordingly, ha~
5 no effect on the capacitance of the capacitor 40P, as e2cplailled `S! 6 previously. l'he ~uperimposed signal may be detected, demodulated 7 or filtered, a~ necessary, following the output 120 to eliminate 8 therefrom components representing the low ~equency control signal ;~ 9 102.
" 10 - 11 The magnitude or the duty c~cle of the control sigIlal 102 may .~, 12 be selectivelyvar~edto selecti~ely alterthe capac~tance ofthe ' 13 capacitor 40P and the impedance of the input lO8. rnese variations 14 may be "manual" or "alltomatic." AutomatiG variation may be : .3 15 effected by varying the control voltage 102 i~ re3ponse to feedback ,~ - 16 ~ ich may be related to the ~,ralue of the 8igIlal on the output 120 or 17 to a signal derived ~om ~laewhere, for example, f~om a uliliza~on 18 circuit comlected to the output 120. Thu~, feedback firom the output f i? 19 122 or f rom the ul;ilization circuit may automatica~ly ef~ect 20 adjustrllent of the capacitor 40P to achieve a~d maintain tor to afEect .`.?
21 L~ a selec~ed manner) 8igIlalB at the output 122 or in the ~l~lization ; ~ :
:~:!
~ ~i 43 ,.
., .

.`;
1 .
. .

.

.

circmt. Manual and automatic adjustment of the control ~ignal 102 2 are indicated by the reference numeral 123 appended to the control 3 arrow of the signal ~ource 104.

~ar~ation in the capacitance of the capacitor 40P in Eigure 3 6 m~y be achieved through the operation of the addres~ing circuit 46.
7 For e~ample. the addressing cirt:uit 45 may affect the impedance of, 8 or make or break, the path to groulld 101 of the subst~ate 43 or ~he electrode 46b, thereby affec~g the amount of de~lection achieved by 10 the membrane 42 for a grveIl cont~ol voltage Vc~ Aff`2cting the 11 impedance of the path to ground 101 may ill~rolve the addre~sing 12 ~t 45 adding or ~ubtracl;ing impedance or elecl;rical ~ nal~ to the 13 path as those ~l~led iIl the art will appreciate.

In alterIIative embodiments, the firequency of the ~put sig~
16 114 may be 9uch that the membrane 42 move~ in response thereto. ;~
17 Thi~ results ~ the capac:~tor 4ûP fi~ciioD~rllg as a non-linear 18 capacitor, the capacitaDce of wbiçh, C(t) varie~ a~ the fiequency of the 19 input aignal 114, Y(t). ~;
i li i .
, ~ ~ ~ 4 ~
1,, . . :
.~, ~ .. -,.
~'. - :"'' ,~r . . : ' ,' , '' : ~ ., i ~ ' :. ' .. '' . ' Figure 4 dapicl;~ a ~er~es connection of a variable capacitor 40, 2 consequently labeled 40S, ~ which reference numerals 8imil~ to 3 tho9e used in Figure 3 are used to denote similar elements. In Figure 4 4, the variable capacitor 40S of the present invention i9 iIl series with ~ ;
the input signal 114. In Figure 4, an output 124 ia connected to the 6 ~ ona~r capacitor plate, i.e., the output electrode 46b (or other 7 conductor), as showIl at 128, which electrode 46b m~y be formed with, 8 and in the same manner a8, the electrode 46b in Eigure 3. U~like 9 the situation in Figure 3-- wherein the electrode 46b (if present) or the ~ubstrate 43, acting a3 the stationary plate of the capacitor 40P, 11 carry cu~ent only dunng chargiIlg of the capacitor 40P-- the 12 8tatiOllaI'y plate 46b of the capscitor 40S, shown as comprising the 13 output electrode 46b, must con~uously conduct current to the output 14 124. This current conduc~onrequirement dîctates that the output eleGtrode 46b be i~ulated ~om the subsl;rate 43 by the insula~ve 16 layer 47. Instead of the ~ingle colltrol elect:rode 46a of ~qgure 3, two 17 con~rol eleGtrodes 46a are ~hown as re~ g on t;he layer 47 in Figure 18 4 îor illu~trative purposes. It will be under~tood t;hat two or more 19 olltput electrodes 46b alld two or more coIltrol electrode~ 46a may re~ide o~ the layer 47 a~d that these electrode~ 46a, 46b may be :

.`J
`~''1' ::?

` ::

interleaved, interdigitated or otherwi~e Eip8t;ially related as necessary L
2 or desired.

~' 4 The capacitance of the capacitor 40S iIl Figure 4 i8 ~et by the 5 cont~ol 8ignal 102, preferably a low f~eque~cy voltage (a~ defined 6 abo~e) which is applied to the membra~e 42 to produce an electric ~'! 7field between the membralle 42 and the control electrodes 46a, which 8 are grounded at 130. The amou~t of de~ection of the membrane 42 . ~
` 9 determines the change in the capacitarlce of the capacitor 40S. The 10 input signal 114, preferably ahigh ~equerlcyvoltage (as defi~ed ~' 11 above), is af~ected by the capacita~ce but ha~ no efF~ct on the deflec~
12 tion of the membrane 42 or, corlsequently, on the value of the 13 capacitor 40S. The input signal 114 is, in efEect applied to a path :~
14 108~2-46b-124, the impedance of which depend~ on th~ value 1~ a~sumed by the capacitor 40S and the ~equency of the ~ignal 114.
16 As with the capacitor 40P, th~ addressing circuit 45 may af~ect the :
:¢
'j 17 colltrol elect~odes 46a or the output electrode 46b, a~d, irl this event, ;`i 18 appropnate connec~ons (~ot shown) will be made Pmong the~e 19 elemellts 45, 46a and 46b. Appropnate "rouling" of these co~ections and of th2 var~nus paths 101, 106, 108, 118, 120, 124 a~d 130, and ".,~ ~ ~
,.` 21 appropriste locations for the various connections 110, 122 snd 128, ~
. ~Ji , ' '.`, ' ' .

~: .

,r - 1 well as the methods for achieving ~ame, may be thoae embodied in 2 a~y suitable prior art techllique relatiIlg to MOS, CMOS or other. 3 hybrid, integrated, monolithic, micromiDiature circu~t manufacture or ~; 4 in modificat~ons thereof as would be krlowIl to those ~killed in the art.
., .~ ~ The same i~ true, of course, regarding the embodime~ts depicted in i 6 otherFigures hereo 8 A specific embodimeIlt of the capacitor 4ûS ge~erally .
ii 9 illustrated in Figure 4, is depicted in Figure 6, wherein there are 1 10 pre~ent reference numeral~ which are the ~ame a~ or si~lar to those 11 used for related elements in Figure 4. In Figure 6, the electrodes 46a 12 comprise a phLr lity of conducl;ive fingers 132 comlected to or formed 13 integrally with a bus member 134. The bus member 134 is, in turn, 14 connected to the ground 130 at a situs which is only achematically ~- 15 depicted. Similarly, the elec~ode 46b comprises a plurality of ",~
16 conductive finger~ 136 coDnec~ed to or form ed integr~lly with a bus 'J
17 member 138, wbich a~sumes identicality with the co~ection 128.
. ; ..
18 The fiIlger~ 132 alld 136 mag be interleaved or ~terdigitated as ~....................................................................... I
1~ shown, with the layer 47 in~ula~ing them ~om the ~ubstrate 43, and ....
- gaps 140 therebetwee~ elecl;rically iIlsula~n~ the finger~ 132 ~m the ~, 21 fi~ger~ 136. A ~ingle capacitor 40~ of a row capa~r~ 40S is .
,.~..;
: .^
.~
~i ~7 ~.,.
.~''''' . .~
, .
-:~
.. . .

:`

:
;
depicted in Figure 6. There may be columns of the capacitors 40S, so , 2 that there i3 presented an orthogonal or other array of variable ', 3 capacitors 40S.
4 Typical elemental DMD7s 30', etc., used as 8ueh, ml~y have ~, 5 dime~ions as small as about 10-12 nucrons ~quare and a~ large as i-l 6 abou~ 25 microns square. It must be remem~ered that, when a DMD
.
7 i8 used as such, e~tremely shorl; respollse time --rapid defleclion Y~ 8 which i~ nearly instantaneous with the application of a control 8ignal~
9 - ia a crucial desideratum. For a givell control 8igIlal, short response , 1 10 l;ime is primarily dependent o~ the mas~ ertia c~cte~is~cs of the 11 de~lectable membrane 32, 42, etc., of the I)MD 30', 40', etc., thu~
12 putting a pre~nium on very small, and, her~ce, low mass, membrarle~.
13 A~ noted above, however, whe~ a DMD ~uc~ as 40 is used as a ., 14 capscitor such as 40P or 40S, it is Ilecessary for the membrane 42 to _~.y 15 be l~e~cally insensi~ve to the ~put signal 114. Al~o, the 16 capacitarlce of a parall0l plate capacitor vane~ e area of it~
` 3 17 plat~. The foregoing ~IUgge9t8 that larger size, and/or higher ma~3 18 membranes 4~ than those present in a~ elemental D~D 40' are ~, 19 deE~irable i~l variable capacitors 40P and 40S. Indeed, it appears that ~ 20 mem~rane~ 42 i~ variable capa~tors of the ~pe in~olved herein -~ 21 should be o~ the order of about 51nm square, or about 40,000 to .. . ~, ~ f 4 8 . s~
., .,., ~ :
.:^
"
,~;., ,. . , ' :~

.`~ 1 250,000 larger in area than 'che deflec~able members of DMD's uqed 2 as ~uch. This increase i~ area bnngs about, of course, a concomitant 3 increase in mass/inter~a.
~-- 4 FiglLre~ 7 and 8 repre~e~t a variaIlt 40a of the variable ., ~, 6 capacitor40 shownin Figure 2 4. In thi8 modification 40a, the h 7 spacer~ 44 have a cross-sectional contour repre~entative of that :~ 8 achieved when a well or volume 142, into which eseh segment 48 of ; :
.:, - ., ~
; 9 the mem~rane 42 defo~ns, is formed by a procedllre ~uch as isotropic 10 plasDna etc~ing ~n o~ygen con~ng a few perce~t ~uorLle.
1~ Moreover,forillustrati~e purposes, discon~nuitie~ 144 ha~e been ~-12 formed in the membrane 42 between the ~egments 48 with 13 diametric~lly opposed edges of the segment~ 48 bei~g supported on 14 oppo~ed spacers 44. In E~guTe 7, each mem ~rane 42 ~egment 48 :
;~ , .
1~ ~es a relativeb thicker, es~eDLti~lly ~n~egral member 145 w~ich ,~ 16 may re~ult from depo~itioDI or forma~on of metal on th~ metal ~ 17 membrarle 42 according to MOS, CMOS or equivalellt technique~. :
`.;j 18 The member 145 co~ributes ~ignificant ma98 to the deformable -.~ 19 ~y~tem 42-145 a~d ha~ a low compliance a~ compared with the margin 146 of the membrane 42. The membrane 42, ~he member 145, 21 the ~pa~rs 44 a~d other elemeIIts described ab~ve may be formed in ` ~1 ''.'.'' :l 49 .. ~
.~,~,.................................................................... .

:

a manner similar to or the ~ame as that employed to produce DMD
2 SL~rs. This forma~on may include alternating and/or repetitive 3 sputter deposition of metals (8uch a8 ~lllmiIlUm or ~luminum alloyj, 4 plasma etching, plasma deposition of o~des and other steps as 5 descnbed in Section 4 of the above-noted sr~c~e by Ho~nbeck and in ~.
;~, 6 commonly assigned U.S. Patent 5,061,049.
,~ . .
-~ 7 8 A~ a consequence of the presen~e of the member 145, which 9 efFectively defi~e~ the segment 48, attr~action or de~lectioII of the membra~e 42 segment 48 and its illtegral me~er 146 toward the 11 control electrode 46a permits the ~egment 48 to rem~ essen~ally 12 flat, with de~orm~tion being confined to the margin 146 of the ~f 13 mem~rane 42 which surrounds the segment 48 and the member 146 . ~ ' i , .
'!.. ~ 14 alld which supports them at 1;wo diametric ~ides. Ihe foregoillg ,........ .
'``j ll; 9upport ~cheme ~upport o~ly at two diame~ic sides of each segment . ~ .
:~i 16 48 of ~he membrane 42-- i8 ~howll in greater detail in Eigure &. T~i8 ~`~ 17 type of ~upport result~ in non-curvilinear deforma~on of the -, 18 membra~e 4~ which involves only opposed porlioDs of the ~ 146 ~i 19 of the membrane 42 and not the segmen~ 48 or tha member 145.
`:~ 20 Su~h defo~mation is repre~ented by the broken l~e 148 in Figure 7.
21 Obviously, the mul~iple electroda 46a,46b ~ uch~e schematically ~j .

:

' . ~'' :-.

, . .
, . . . : .

. ~ -- 1 shown in Fi~,ure 4 may be implemented in the embodiments of 2 Figures 7 and 8, if desired, although the electrode 46b i8 not visible in '!
.1 3 Figures 7 and 8. I~ Figures 7 & 8 the station~ry plate of the .~ 4 capacitor 40a may, a~ ~n other Figures, ~omprise the substrate 43, or , ,, ~
5 the output electrode 46b. The capacitor 40a may be par~lely or i~ 6 serially related to the input 8igIlal 114 a~ in Figures 3 and 4, 7 re~pectively.
.i 8 9 Figure g illustra~e~ an alternati~re variable capacitor 40 ba~ed on eleme~tal DMD'~ 40' of the meml~rane type 8ilI~il~ to tho~e show ~,, ~'7 ~ Figures 7 and 8. In the presentatiorl of Figure g, the photore~i~t 12 spacers 44 are replaced by metallic ~upport po~ts 150t which may be 13 produced by the so-called "buIied hinge" method~ disolosed i31 the 14 aforenoted '049 patent and the ar~cle by Honlbeck and cornpnsillg ..... .
16 MOS,CMOS or other procedure~ which include repeti~Ye/alte~a~g 16 metal sputtering, pla~ma 02~ide foImation, plasma etching and other :
. i 17 known ~tep~. The po~ts 1~0 ffinction much a~ the input 108 a~d the ; 18 connection 110 to th9 membrane 42 in ~qgures 3 aRd 4.
.; 19 .i, ~
~ .` 20 Portions of tlle addresfling circuit 46, such as a~ eleG~rode 162 ,, :j ~`;l 21 and the control electrode 46a are sho~ i~ Figure 9 ~s resi&g on .,.,~,i ~ ~ , :''i ~, , : ` ~

1 the o~ide 47 deposited on the substrate 43. Both the electrode 1~2 2 and the conbrol electrode 46a, as well as the electrode 46b (w~ich, if , ~
3 pre~ent, is not visible in Figure 9), which may act a~ the stationary 4 plate of the variable capacitor 40, might preferably be recessed :
beneath the upper surface of the subs~ate 43 and/or compFise an ~, 6 appro~imately dopedregionthereof. The electrode fimctions much 7 as the path 118 in Figur~s 3 and 4. The electrode 152 which is 8 electrically continuou~ with the mer~r~e 42 and its member 14~, 9 may be used ~ impresa on the membrane 42 and the member 145 of 10 ea~ capacitor 40 a voltage which, iIl conjunction with the voltage, :.i 11 ground or otherwise on the control electrode 46a (or on the ~ubstrate ~; 12 43, if the electrode 46a is not present) con~ributes to the co~t;rol the 13 amolL~t of deiflection e~perienced by the membrane 4~ and the 14 member 145 of the capacitor 40. 1~ this e~d, the voltage may be ~ :
applied to the me~rarle 42 by the support post 150, which is in i,~ 16 co~tact with the electrode 1~2. Each membra~e 4Z i8 diametrically 17 ~upport;ed by two po~t lS0. As in Figures 7 &: 8, due to the pre~ence 18 of the ~iglbly compliant ~ 146 and the lo~ complia~ce ce~trally 19 located member~ 145, piston-like deformalioIl of the meml~ e 4~
. :~. 2û occurs aa the members 14~ re~ill generally parallel to the plane of "~

~`

the substrate 43. Such deforma~on i8 represe:nted by the broken 2 line~ 148.
3 :~
. . ~
4 A~ will be appre~ated, the electrodes 46a and 152 are . 5 controlled, energized and deer~ergized by the addres~ing circuit 45. If ~i~. 6 the electrode 46b i8 absent, the capacitor 40 of Figure 9 i8 usable 88 .; 7 depicted in Figure 3. If the electrode 46b i8 preaent, the capacitor 40 8 of Figure 9 is u3able as i~ E igure 4. :
..
,~
.
Eigure 10 depicts a generalized elemental DMD SLM 50' of the ~$ 11 can~lever-beam type used as a v~able capa~tor 50. Element2 ~,.
12 which are similar to those 8hOWI1~1 other ]Figure~ bear the same or , ~j ;~i 13 similar reference numerals.
~! 14 :~i .`., .'a 15 The member or segmeIlt 58 in Eigure 10 compri~es a highly 16 compli~r~t por~on of a rela~vely thin underlying metal ~tratllm 51 o~
~^.; 17 w~ich i~ depo~ited a rela~vely thi~, ma~k-pattemed metal stratum 18 52 w~ich has a low compliance member 58. In the DMD 50' the thic~ l :
;~i 19 ~t;ratum 52 is abserlt at ~elected ~ites, as ~ho~vn at 64, leaviIlg only ~ .
the thi~ stratllm 51 to act as a ca~tileYer beam 66. In the DMD 50' 21 the remaining portion of th~ t~ick stratum 52 w~ich remai~, i.e., the -,'"`? . :: i.-i~ 53 . ........................................................................... .
$
,'`i, " , ~ :~:;

~q :

`. 1 member 58, func~ons a~ a light-reflective p~cel or mirror, the rigid, :
2 low compliance nat~Lre of which confines can~lever berlding to the ., 3 beam 56. In the capacitor 50, the member 58, ~ncluding the 4 underlying thin stratum 51, acts as the movable plate of the variable, air-gap capacitor 50.
~^ 7 The length, width, thiCIm!388 and mater~al of the be~ 56 and .. - 8 the ~ize f~nd mas~ of the member 58, inter ia~ may 5~11 be adju~ted to 9 effect a de~ired amount of deflection of l;he member 68 i~ re~ponse to an elect~ical field between the member 58 ~d the control electrode ., 11 46a. These same parameters may al80 be adju~ted 80 that the ~ 12 member 58 deflects in response to, an in synchronism with, the low ;,, ~ 13 firequency control signal 102 but not to the high ~equency input ~,. 14 ~ignal 114. Although the beam~ 56 and the, movable capa~tor plate .~ 15 or members 58 are ~how~ Y~e 10 a~ ~upported by insula~ve 16 spacer~ 44 hav~ngrectallgularcross-sectioDs, ~pacers ofth~ type 17 ~hown ~ll Figure 7 may be used, see Figure 12, as may ~upp~rt po~ts ! r,~ , ~ .
18 150 a~ shown in Figure 9, see Eigure 11. As in other EYgures, the "~ 19 output electrode 46b w~ich serves a~ a ~ ionAry capacitor plate may or may not be prese~t. Moreo rer, the capacitors 60 of Eigures 10^12 . ~ 21 maybe operatedin l;he same man~er a~ shownillFigure~ 3 and4. :
,~
.~ 54 ., :
... . .
..
!~ . ' . ~
. , ' , As v~ewed from the top in Figures 13(a) and (b), the capacitor3 2 50 of Figure~ 10 or 12 are depicted as haviIlg both the control 3 electrode 46a and the output electrode 46b. The relatively large area 4 output electrode 4ffb (not v~sible in E'igures 10 or 12) renders these capacitors 50 capable of achieving relatiYely high capacit~ces, w~ich 6 vary as the area of the plates 46b,58 thereo Making ~e out~ut .. 7 electrode 46b a8 large as poasible i~, of course, a technique that can ,:! 8 be used i~ all of the embodiments hereof to ma~imize capac~ ce of 9 the voltage-variable capacitance~. ~3ince the moval~le capa~tor plates ;: 10 58 in E'igure 13 deflect asymmetrically relative to their ~es of ,~ 11 symmetry, placement of the control electrode 46a and the output ,.
12 electrode 46b anywhere ~ereunder i8 snfflcieIlt to effect deflectio~
13 thereof and to alter the capacitance of the capac~tor 50.
,,.~
.; 14 3 ~ .II1 Figure 14 there are depicted four l;op views of DMD SL1~8 16 60 ofthe torsion-beamtype (none be~g show~ side elevatiorL~. The 17 tor~o~ beam capacitors 60 may be ~imilar to the caD~lever beam ~; 18 capa~tors 50 of Figure 13. InFig~lre~ 14(a)-(c) torsionbeams 62 are ~;
19 fo~ed i~l a maD~er ~imilar to that i~ ~}ich the cal~lever beams 56 '~J . :-of Pigure~ 10-13 are formed. the torsio~ beams 62 ~pport the 21 movable member~ 58 symmetsi~ally about and relative to a~
,. ... ~
;:$, 55 .,.s, ~:
.,~.j, .`"~

",!
.. , 1 rotation 64 of the members 58. As a consequence, (1) the output - 2 electrode 46b ha~ a amaller area, rela~ive to the area of the member 3 58~ a9 compared to the output electrudes 46b of Figure 13, and (2) 4 the control electrode 46a and the output elect;rode 46b must be 5 asymmetricaLly located relative to the tor~ion beams 62 and the a~i~
6 of rotation ~4. The first con~equence follows f~om the fact that equal -; 7 areas of corltrol electrode 46a on either ~ide of the a~is 64 would 8 render the control electrode 46a incapable of deflecting the member . 9 58, si~lce equal force~ would be applied to the member 58 o~ both . . . ~
10 side~ of the a~s 64. The second consequence ~ollow~ ~om the fact 11 that, upon deflection of the member 68 about the a~i8 64, with a i: ,i ~ 12 symmetrically located output electrode 46b one-half of the capacitor ,.~
:~ 13 ~0 would e~penence a capacitallce increase, while the other half 14 would e~per~ence aIl equal capacita~ce decrea~e, the net of the 15 capacitance changes being zero. It should be noted the Figure 14 16 (a~d 13, aa well) depict the beams 62 (a~d B6) a~ ~upported by 17 ~pacers 44. These ~pacer 44 may, of cour~e, be replaced by the po~ts .,...................................................................... , ~
18 150 of Figure~ 9 and 11.
"'~ ' ' 19 j ~ -~0 In Figure 14(d~ the torsion beam 62 and the a~is 64 are 21 a~ymmetric relative to the member 58, a~d pracl;ic~lly a~y placeme~t ~ ., : -.,. ~.
. .

of the electrodes 46a and 46b is ef~ective to yield an operable, vanable -` 2 capac~tor 60. Thu3, the capac~tor 60 of Figure 14(d) i~ a close - 3 func~onal an log of the canl;ilever beam capac~tors 50 of 1i'igl~e9 10-4 13.
., 6 An analy~i~ of capacitance variations dur~ng dif~erent amounts '''!~ 7 of deflection in the capacitors 30,40 (e~ccept for the capaeitors 40 of ~;. 8 Figures 7-9), 50 and 60 i9 ~omewhat co~nplicated. Thi8 i8 due to the , 9 non-linear, clLrved shape changes which occ~r in the membranes 42 of .` 10 the capacitors 40 and the pre~entation of decrea~ng effective area by , ., 11 the members 68 of the capacitors 50 and 60 in E'igures 10-14. The 12 defiection e~hibited by the capacitor3 30 of Fi~ures 7-9 --de~cnbed , ~l 13 above as piston-like-- results ~ their members 58 rem~ both -.
14 flat and ~ub~tantially parallel to its 8tlltiOllary plate (the 3ubstrate 43 : ~:
15 or the output electrode 46b), which renders analysl~ le~s complicated.
16 T~i8 virtue i9 shared by the capaoitor 70 of F'igure~ 1~-17.
17 ~: ~
18 . Ill Figure~ 15-17, the capacitor 70 ha8 a moYable meml~er 58 19 similar to thosa shown in ~qgure~ 10-13. Iha member ~8 i~
. ~upporl;ed by beams 72 which are combined caIll;ilever beams alld :
21 torsion beaIns. 8pecifically, a ca~tilever 8eclion 74 i8 ~upported 8t ', '~
'!i 57 ..,~
,.;~ :
s,, .

:

`:
.~
one end by a ~paoer 44 (or 9Upport po~t 150) and i8 conti~uous at itis 2 other end with one end of a torsion section 76. The other end of the 3 torsion section 76 i~ contiDuous with the me~er 58, specifically with `! 4 the thin stratum 51 thereof. The thickness, matelial, le~gth and `;' 5 width of the sections 74 and 76 i~ ~elected BO that the modes of 6 defo~ on of the ~ections 74 and 76 are, both canlilever and . 7 torsional. Attrac~on of the member ~8 toward the oontrol electrode ~3 8 46a ef~e~s pi~ton-like de~lection of the member 58 as the cantilever ~ 9 sections 74 bend downwardly and the torsion sections 76 twist : : .
i~ 10 slightly about a~e~ 78, which are generally :normal to th8 a~sociated 11 ~ide of the plate 58 and the a~sociated cantile~rer ~ection 74. The ~ 15 12 foregoing deformatioD~ of the section~ 74, 76 e~ect a slight rotatio~ of 13 the member 58 in the plane of Figure 15, which rotation has a `
14 negligible e~ect on the capacitance between the mem~er 58 and any ~;d5 16 unde~lying output electrode 46b. In Figure 16, the electrodes 46a and 16 46b are configured along the lines of their counterparts in Eigure 6;
17 i~L Figures 16 a~d 17 the ele~ode~ 46a ~nd 46b ara not digitated aIId 18 the electrode 46b is not ~isible (if it i~ pre~ent).
19 . -::
20 - Tu~ing no~w to Eigure~ 18, there is æhown a device 80 ba~ed on . 21 aD elemenLtal DMD~ SLM 80'. The de~ice 80 i~ a ~wiitch, rather l~i, .. . .
.. . . .
.. ~
, :

:`~
than a capacitor, as shown m earlier Figures. The sw~tch 80 includes 2 a thin, high compliance metal mem~rane 82 ~upported above a ~.
:. 3 ~ubstrate 83 by, and ele~rically con~nuou~ with, metal posts B4 4 similar to the po~ts 150 iIl Figures 9 and 11. Fonned i}~ d/or on the .'3 5 substrate 83 is an addressing s~ uit 85. An appropIiately constituted :;!
- 6 portioIl of the ~ubstrate 86a serves as a coutrol electrode which i~
7 selecti~ely energized by the addressing circuit 85. A ~eparate control , ~
8 electrode 86a, similar to the electrode 46a i~ earlier Figure~ may, if 9 nece~sary, be employed. Two separated output electrodes 86b re~ide ..... .
i ~ 10 o~ a dielectric layer 87 formed on the subs~ate 83. A de~lectable . 11 member 88 constitutes a central portion of t~e membra~e.

..
... 13 The deflectable member 88 is ~upported by the posts 84 na ` ;
14 narTower margill8 90 formed by selective removal of the membrane 1~ 82. The margins 90 are, becsllse oftheir DlalTOWlle88, more compliant 5i,,, 16 tha~ the member 88. If it i8 nece~ary to render the member 88 even ~ :1 ,~ 17 le3s co~pliant, and/or if it i8 de~ired that the configu~tion of the ,~ 18 member 88 be planar, or nearly 80, dunng deflecl;io~, the member 88 19 may be made thicker than the m~s 90. For e~ample, a tbicl~
20 metallayer 92 (showninphantomin Figure 18~) maybe positioned 21 on the member 88, as by MOS, CMOS or other depo~itio~ 8tep~1. The '`. `, ' ~'`"`' ,' "'1 .

....... , , . .,, .. ", .;.,i.,, ., .. .. . ~, .. .. . ~... ....... .... . . .

thick metal layer 92 serves the same fimclio~ as the member 14i5 in `. 2 Figure in Figure 9. If the layer 92 i8 not present, the membriane 82.. 3 will tend to deform curvilineraly ~imilisrly to the membranes in 4 Figures 24 and 6, although tbis tendency i8 ameliorated to some :' 5 e~tent by the width of the member 88 being greater tha~ the width of6 the marglI18 90. The pre~ence of the lsyer 92 and/Dr the difference 7 width of the member 88 i~d the margins 90 will re8111t ill pi~ton-like ::8 or qua~i-piston-like deformation of the type depicted i~ E igures 7 and ~:
Y 9 9 ' ;~
` " ' 11 Elec~ica~ly cont;inuolls with the posts 84 and residing on the 12 dielecb~ic layer 83 are conductors 94 which ser~ve the same purpose as 13 the electrodes 152 in Figure~ 9 aIld ~ hese conductors 94 are 14 energized by the addres~ cirScuit 8~i or by other circuitry to impose a selected poten~al on the membrane 82 axld, accordingly, on the 16 member 88, relative to the oontrol electrode 86a.

18 The potential im~o3ed on the member 88 ~teracts ~vith the 19 poten~al imposed on the coIIl;rol elect;rode 86a ~o move l;he meml~er .: s :
88 out of it~ first po8itio3L Itlstead of setting the value of the ~`~i 21 capacitance of the device 8û a~ in other embodiments, movement of ~ .
.:
:, . . .
: ~
.

.~.......................................................................... .

the member 88 out of the fir~t posil;ion results in the member 88 2 being moved to a second positinn, as indicated by the brol~en line 96 -.` 3 iIl Figure 9(a). In its second po9ition, the member 88 engages both 4 cutput electrodes 86b rendenng them electrically continuous the ;: ~ member 88. The member 88 aDd the oul;put electrode~ 86b, 6 accordillgly, constitute a switch 86b,88 which i8 "open" when the ;~ 7 member 88 is i~ the first posi1ion and i~ "clo~ed" when the member ::
8 88 i8 iIl it9 second position 96. Ihe output electrodes 86b may be 9 comlected to, or may constitute the termini of, reapective .; 10 transmi~aion line~ 98. The transmis~ion line~ 98 may reside on the :~ 11 dielectric layer B7.
12 The device or ~witch 80 of E igure 18 may, as described abwe, -~ 9.
.,. . , : ~
13 be used to aelectively sw~tch trarlsmissionlines 98. Similarly, 14 selecti~e, digital positioning of the member 88 may be u~ed to block orunblock an optical pathwhich estend~ perpendicularto the 16 direction of movemeIlt of tbe member 88 between its first and ~econd 17 posi~ions. Thi~ selective moveme~ of t;h~ member 88 i8 co~trolled by 18 t}~e pote~ imposed oll e m~mber88 arld onthe control electrode 19 86a by the addressing circuit 85 or other fiacilitie~. Thus, the s~itch - 80 may sen~e as an electrical or op1ical switc~L The liIle~ 98,98 may 21 be re~dered ~el~ictively conti~uou~ by terminal switche~ 80 between ,.,.~
!.,..i ,':."j .:~' ~ 61 , "
. . il; :
':,z .~ .
.", .
. - .
..... .
. ~;

which are ~erially/parallely connected vanable capacitors ac&ording to 2 e~rlier Figures for adju~ng the impedance between the lines 98,98.
::, 3 4 The switch 80 may be used to 8witch microwave and millimeter-wave high ~equency Big~lal8 presellt on the transmis~ion "
~:, 6 li~e~ 98. To thi8 end, the substrata 83, which in earlier embodiment~
7 is typica11y ~ilico~, may be GaA3 or other suitable material. Of ~:8 course, GaA~ may also be used for the various ~ub~ate3 of the 9 earlier des~ibed embodiment~ if ~igh frequencg ~put sigDals are ;~
applied to the capacitors thereof. The stray and other capacitance e 11 and khe parasitic and other resiatance of the switch 80 may be ~;, .
12 adjlLsted and ~elected to achieve selected goal~, such as minimized 13 stray capacitance and minimized isolatioD~-- when the ~witch 80 is 14 "open" and minimized parasitic resistance --and miDimized inser~on ;
~ . , 10~8- whe~ the switch 80 i9 "ClOBed." Ih~ ~tenal, ~hape and other 16 parameter~ of the membrane 82 may ~1180 be adjusted or selected to .~-j 17 ac~ieve ~electedimpedancematchingbet~1veenthe traDs~i~ioD.lines 18 9~ when the switch 80 i~ "c30~ed." O~e tech~ique which may be used - 19 to "tu~e" the ~witch 80, as well as the earlier descnbed capacitors, is .- ~ , 20 ~ electi~re removal of small port;ions of the margins 90 of a~
21 oth~wi8e complete ~witch 80 (or the membraIle~ or beamA of the - ~., ,.
. ,~
''' , : .

capacitors). Such ~electi~e removal may be ef~ected by an 2 appropriately shaped and ~ized bean of energy, such as that produced 3 by a trimming laser or similar apparatuis. The thiclme9~ of the 4 marg3n8 90 (and of the membranes and beam~) may also be adjuAted or selec~ed to achieve a de~red compliance 90 a8 to ~ze or .
6 otherwise selectthevoltagemagnituderequiredto "do~e" the switch 7 80 (orto adju3t capa~t~ce). ~:
l O ~ ~.
,, O
.~` 9 The svritch 80 may b~ co~figured to perform multiple "thl-0~8"
:~ 10 i~stead of the single "throw" illust~ated and described. For e~mple, :~ 11 if the membrane 82 deforms curvili~early rather than planarly, 8 12 first amount of de~lect;ion or deformation may permit the membrane 13 82 t~ bridge and illterconnect two closely spaced electrodes, 8imilar to 14 electrodes 86b, while a ~econd, greater amoaDt of defonnation may resultillthe membr~ne 82 additiollallybriclging two other electrodes, ~ ~
16 also similar to t;he electrodes 86b, which are farther apart. The ~ ~:
~!~ 17 foregoing muItiple "throw" ~cheme may al80 b~ implemellted by the `~i 18 use of two or more ~witches 80, each selectively interconnecting !.
19 re~pective pair~ oftra~lsm~ oll line~ g8,98. The sw~tches 80 may be .`q. 20 ele~ically asso~iated ~o that a firat co~l;rol ~ al close~ one thereof ..~, 21 YYhile a aecond larger iDpUt ~ al clo8e8 tWo thereof, a~d so o~.
:::
:~ 63 ,, . , :, ., -.~ ,~ . .

.~ 1 Appropriate a~sociation of plural ~witches 80 control~ng respective 2 transmis~ion lines 98 or delay line~ may also permit in digital 3 selection of the lines. I`wo or more ~w~tche~ 80 may be put in series i 4 to iIIcrease isolation, while if put in parallel, the switches 80 will ,.i .
5 reduce insertion 108~. -~ .
~;^Ss 7 Figure 19 depic~s a device 160 which sen~es a~ a vanable 8 capacitor. The variable capacitor 160 of P5gl~re 19 com~ines certai~
., . :
j~ 9 conetructional features of di~3Ferent previously de~cn~ed capacitors.
10 For e2~ample, a deformable membra~e 162, ~imilar to that found in 11 Figures 2~, 6 and 18 is suppor~ed between a conductiYe post 164, 12 similal to the post showninEqgures 9, 11 a~d 18, a~da~ ulative 13 spacer 166, similar to that shown in E igurell 24, 6-8, 10, 12, 16 and 14 17. The capacitor may fimc1;ion in serie~ with an input 8igIlal, along 15 the liD.e~ of the capacitor 40S ~ho~vn in Eigure 4, and to that end, 16 may al~o includes an output electrode 168 below the membraIle 162 ~-17 and residing on a su~ ate 170 wl~ich ul1;imately BllppOrt8 the other ~i~i 18 elements. The output ele~ode 168 ~y be co~ered ~nth a non~
19 conducliYe o~cide 172 which "set~" the ma~imum capacitance and !20 ~;srhich pre~e~ mechanical engageme~t and shor~ng between the ; ~
. ...................................................................... . .
: ~.

:

-:~

membrane 162 aDd the output electrode 168 when the former i9 2 defonned or de~ected out of it8 fil~t, no~nal position.
4 In the capacitor 160 of Eigure 19, control 8igIl}118 which may be produced by an addre~s circu~t show~ o~ly generally at 174, are 6 applied to the poP.t 164 by a cond~tor 176 electrically co~t;inuous 7 therewith The post is electrically conti~uou~ withthe membrane 162 j 8 30 that Bigllal8 OIl the conductor 176 are applied to the membraIle 9 162. The output electrode 168 also serves a~ a control elecl;rode 178 ~o thatthe lowi~eque~ po~enti~lbetweexLthe membrane 162and 11 the elect;rode 168/178 set~ the capacitaDce of the capacitor lL60. E[igh 12 f~equency input 8ig~1al~ are al80 applied to the conductor 176 where 13 they are selectively af~ected by the capacitor 160. As with other 14 embodiments, the addressi~g ci~Gait 174 or other facilities may `~ 15 produce or modify the oon~ol 8igllal8 aIltl the iIlpUt ~ als.
;~ 16 17 The capacitor 160 may be used with high ~equency, ., 18 millimeter-wave or microwaYe ~Dput ~gnals. Again, to pe~t such l:
19 u~e, the subst~ate 170 may be GaAs or other suitable material. As ~3~i~ 20 should be obvious, the capac:itor 160 may fi~ction ~ p~el ~q-th the ., 21 input s~g~ , similar to th~ capacitor 40P of Eigure 3, by replaci~g the .3 ''' . ~ .
.
... , ~ .~
. ~ ~

insulative spaces 166 with a post, similar to the post 164 and 2 grou~ding the substrate 170 orprovidingthereon a grounded 3 electrode subjacent to the membrane 162. Parallel and sensl 4 combi~alions of plural capac~tors 160 (aDd of the earlier de~cnbed capacitor~) may be utilized to achieve digitally ~electable capacitance 6 r~nges. Such combinations of capacitors 160 may filld use in v~nable 7 filters andimpedance matchingnetworks, aIIdmaybe used to adjust 8 the passband or ~topband ~equen~es of communica1;iorl or radar 9 ~Iy9tem8. COlnlblIlEltiOD.8 of the capacitor 160 msy also be ~ed to tune ~ quency o~cillator~ and, whefi combiIled with a feedback: loop, 11 to co~pensate for driflc caused by ag~g or other e~cts.
: ,!

13 Figure 20 depicts vanable impedance transmisaion liIIe~ 180 ~ :
.~, .
~i 14 which i~clude variable capacitors, shown only generally at 182, which corporate the prin~ple~ of the pre~ent in~ention. The capscitors 16 182 may take the form of any of the pre~nou~ly descnbed 17 en~odiments, and are ~howD as be~g 8imilarto the capacator 40Si~
18 Figure 3, va:nous eIements, ~uch as the electrode~ 46 and the control 19 and input ~ignal facili~es not be~g ~hown ill Eigure 2~. The . !20 tral sion liDes 180 i~clude a co~iinuou9 metal membrane 184, 21 p~odically ~upported above a 8Ub8trglte 18B by separated spacers `.` 66 .~,........................................................................ :

188 a;ld a ground plane 190. The spacers are insulative and, in 2 efEect, div~de the con~nuous membrane 184 into separate deforma~le .
3 ordeflectable members 192, each of w~ichis supported on two ~'t 4 diametric ~ides abo~re a porl;ion 186' of the substrate 186 and i~
presentiD one ofthe capa~torQ 182. Thus7 each capacitor 182 6 e~ectivelycomprises a movable plate ormember 192 overlying a ~? 7 stat;iunary plate or associated substrate portion 186'. The coIltinuous 8 membrane 182 ser~es to render electric~lly continuous adjacent 9 capa~tor~ 182, thereby fi~ctioning a8 the output and co~ection 120 ., ~ .
'~ 10 and 122inFigure 3. Addres~ingc~ts, generallyindicated at l94, ~ ;
11 are fonned on and ~ the ~u~strate 186 and selecliYely produce 12 appropriate electrostatic fields between the 8tationary plate 186' alld . ., 13 the movable plate 192 of each capacitor 182 to selec~velyand ,A, 14 independently adjust the capac~ce thereof.

16 ~he width of each member 1~2 may be constant or m~y be 17 di~erent ~om that of the adjacent members 192 a8 BhOW~ ~ E iguses ~YI 18 20~b) and 20(c). Accordingly, the ei~ective area~ and therefore the . ........................... .
x 19 capac-tance, of each capacitor 182 may be dif~erent. Each member I, 20 192 i8 digitally, moYable or deflectable, that i8, each member 192 i~
`~ 21 either in it~ fir~t positio~ shown ~ ~olid line~ in Eigure 20(a), or . 1 "
., ~ ~ 67 - ~
.~
`
~"~,, , ,;, .~ .,.; .

.. !

:, .
,' :
in a fillly deflected ~econd position, represented by broken lines 196.
2 Each member 192 may also be movable in analog fa~hion, i.e., by an 3 amount proportion~l to the control signal 102. Thus, each capa~tor 4 182 may have a ullique minimum, ma~imum or intermediate ;
capaQta~ce value relative to the re3pec~ve capacitance~ of the other 6 capacitor~ Figure 20(b) the varia~on in width of the members 192 , 7 i8 achieved by amooth tr~aitiona, while in Figure 20~c) the 8 tran~ition~ are stepped.
g .~
Prefera~ly, the inductance per unit length of each member 192 11 is made large. Thi8 maybe achievedby fo~L~ingthe members 192 as ~, 12 long, nalTow structures, best illustrated by Figure 20(c). Although 13 not specificalIy depicted in Eigure 20, larga inductance per u~it 'i 14 length may al90 be achieved by increas~g the diista~ce between adJacent spacers 188 or decreasing the width of the members 192.
~. 1~ '' ''~
:, 17 By selecl ively adjus~ng the capacita~ce to grou~d o~ each 18 cspacitor 182, the overall caipacitance of the transmission li~es 180 !~
.`j, 19 maybe ~lteredas de~ired. ByU~illgthe tran~ ionliIle~ 180 to 20 - transmit sig~als ~avirlg wa~ele~tl~s aDid fi~equencies comparable to -~ 21 the dime~lhion~ of the members 192 aIld by ~cludi~g the ~ 6 8 .,.. , ` ~ .
~ ~j , . . .
,. . .
. .

`j 1 tran3mis~ion lines 180 with other re~onant or coupled device~ or 2 topologies, ~mpedance adjustability and performance may be selected .,.
3 over wide, nearlyinfi~ite ra~ges.

Capacitors such as tho8e 182 ~ Figure 20 may be incorporated 6 into a wide variety of tunable or f~equency-agile couplers 200 which 7 are generally illustrated in Figwre 21, in which ~imilar elements be~r 8 the same reference numeral8 a8 i~ Figure 20. I. Figure~ 21(b) -26.
9 the devices or capa~tors 182 and 80 are geIlerally shown as 10 rec~gular areas w~ich i.~ intended to co~vey only the location 11 thereof, the specific ~tructwre bei}lg as depicted in earlier Figure~.
i i , 13 Figure 21(a) is a tunable branch line coupler, th0 branches of 14 wbich each include a single row of capacitwrs 182 as in the .~1 15 transm~ssion~ es 180. Figure~ 21(b)-21(d) are, respec~ively, a 16 tunable branch line coupler, a tunable rat race coupler and a tunable ' '~'1 ~ 1 17 a8y~et;ric coupler, in the br~nches of each of which there are ... . .
, .' 18 p~e~ent array~ ofthe Mpacitor~ 182. The ~equency of operation and ,:
19 the coupli~g of each coupler 200 ~es as the characten~tic 20 impedance thereof i8 challged by ~ele~ive adjustment of the .~ i ', 21 capacitanee of the capacitor~ 182. I~pic 11y~ the widtlh of the :"~ ,' ' .
," i, ' .

;

members 192 of the capacitorq 182 ILqed in the couplers 200 have, but 2 need not neces~qarily have, con8tant widths, rather than the varyin~
3 widths of Figure 20. As with the frequency-agile transmission li~e~
: 4 180, the substrate on which the coupler~ 200 are formed may be 'J
-~, 5 tailored to meet the requiremeIlts of ~he input 8igrlal8 with w~ich 6 they are used. For e~ample, when the iIlpUt 8ig~1al8 are microwave of - 7 millimeter-wave 8igIlal8, the ~ubBtrate~ 186 may be GaAs or other ,j ~ .
`'. 8 8111table material with addre~ CirCUlt8 194 aleo approp~iate thereto ;"
9 fonned in and on the 9ub8trate~ 186. A1E~O, if 1088 co~iderations 80 J,i, 10 dictate, the membera 1~2 of the capacitors 182 ~ well as the !
,, i, 11 me2~bers of previou~ly descr~bed devices according to the present ;~ 12 inven~on- may Dlclude or be covered ~n~h gold or other ~u~table :`,13 metal to reduce high frequencylossea l1he gold m ay be deposited Ln 14 aay e~pedient mauLler,such as by vapor deposi~on or plat~ng. :
, .

16 Capa~to~s 182 and a~rays ~hereof w~ich are sinn~ar to or ~he 17 aa~e a~ tho~e u~ed iIl the traD~misaion li~les 180 and the coupler~ :
18 200 ofE5gure~ 20 a~d 21 may be Lncorporated rlto radiat~lg and 19 ab~or~ing structure~, such a~ anteRna~ of all type~. Frequency-agile ~.. '.` , .~, 20 ~d pattern-agile antenna~ which may u~lize the capa~tors 182, et ~::
..~
.. ~ 21 al, of 1 he pre~ent in~enl;iorl ~lude patch; spiral; slot; microstrip (e.g., . .
, ,.

~, , .

,.,., , ~ , ~:-." ' ~

a patch radiator fed by a hybrid coupler of the type shown in Figure . 2 21(a) or 21(b)) of all shapes, ~ncluding ~quare, disk, rectangular, 3 ellipse, pentagon, ring, triangle alld ~emi-di3k; arrays of all types, :
4 including microstnp antenna arrays; and phased array8 ~nd coupled ,:, structures of all type~. EYgure 22 depic~3 oDly a portion of a 6 f~equency-agile and pattern-agile patch aDte~ma 21û which 7 incorporate~ an a~ay of capacitors 182 according to the pr~ciple~ of .. 8 the present illvention. The incorporation of such capscitor~ 182 into 9 other antennas will be appare~t to tho~e skilled in the art aflcer ~ ' .
~i 10 referri~gto this ~pecificatio~.
., 11 ~,,, il 12 When the capacitors 182 are incorporated iIltO an alltenna, 'I 13 8uch as that 210 shown iIl Figure 22, the sl;~strate 186 may be mElde 14 of ~artz or other anten~a-suitable material. Moreover, dependi~g on '; 15 the f~equencies of the transm~tted or received input signals, the i i` 16 mPmbers 192 of the ~ray of capacitors 182 may include or be covered 17 with a lo~ ohmic 1098 metal 8uch a8 gold. According to the present i , 18 inve~tio~, each capacitor 182 fo~ing the ante~ 210 is ~dividually and indepeDdeIltly addressable to adju~t the impedance of each such capacitor 182 for a give~ f~eque~cy of i~ut 8igIlal 114. AB noted, 2ï ad3ustment of the capacita~ce adjust~ ~he impedaniGe OI thie anteDna 3~
L.

,:, , .

. ~ :

:

210, as well as its radiatin~/absorbing patten~ a~d wavele~g~h. In - 2 thi~ fashion the antenna 210 may be tuned for a ~pecific radiat;ion .~ .
` 3 pattern and fi~equencyrange.
~ 4 ,........................................................................... .
'r''~ 5 As should be apparent, array~ of the capacitor~ 182 6 incorporated into a wide variety of other electrical dev~ces, including ~; 7 de~ices particularly useful at millimeteI-wave aIld m~crowsve ', 8 ~equencies, such as FIN lines, wavegLude to microstrip t2an~itioDs, 9 resonator filters, resonators ~d filters. EYgure 23 portrays two .... . .
10 a~pects of a porl;ion of a F~ Li~e 220 whi~h cont~in~ anray R the `~ 11 capacitor~ 182, while Figure 24 depicts a~ array of capacitors 182 12 incorporated illtO a waveguide-to-~icrostrip tran~ilion 230. The `~ 13 waveguide 232 may include a wedge or FIN line 236, which may be 14 3imilar to the FIN line 220 of Figure 23, wilile the micro~trip 234 may be ~imilar to the t~Dlli88iOII lille 180 of Figure 20 and may ~ 16 i~ de or be ~d by a coupler, 3uch a~ those 200 shown i~ Figure 21.
.'~.,J' 17 19 Another use for array8 of the prin~ples of the pre~ent iIlven~on which i~ more related to the 8witch 80 of Figure 18 tha~ to 21 the capacitors 182, i~ incorporal;ion thereof i~to some or all of the . ., 1 .-: ., ~
!i ~ ::
?',~
:. ' ., . ` ::
'. ^ `, ~ : :
`,, ' `-':

~tenor surfaces of the WallB of a walveguide 240, as shown generally 2 Lll Figure 25. ID this embodimerlt, movement of the members 88 of 3 the device or switch 80, which members 80 serve as a portion of the 4 interior surface of the waveguide 240, selectively reduce ~or increase) the cross-section of the waveguide 240, thereby alteri~g the electrical characteristics thereo When reducing the cro~a-aection of the . i 7 waveguide 242, the members 88 are repelled firom the co~trol ".
8 electrode 86a by poten~als of the same polarity on the members 88 ;
9 and the control electrode 86a.
,/ 10 .:
11 llhoae ski~led in the art will appreciate that various changes 12 and modifications may be m~ade irl and to the above-described 13 embodiment~ of the present i~vention witholllt departing ~om the ."
~. 14 sp~r~t, scope or coversge of the following claima , . .

,,~
"~1 :
~,, :.., ~,.j 1 ~f ~ .
~,, .
'7'''``1 ' ~
:~i 73 ';. .- ~:
, j .
,,~,',, : :

.. ~, .

, ~ . - . . . ~ . .. .
. .; . ~ , ~ - ~, . . . , : .. .

Claims (130)

1. A microminiature, monolithic, variable electrical capacitor for affecting an input signal, which comprises:
(i) a substrate, (ii) an electrically conductive member monolithically formed with and spaced from the substrate, the respective plates of the capacitor being the member and the substrate, (iii) means for mounting the member for deflection of a portion thereof toward and away from the substrate and for storing energy when the portion of the member deflects out of a normal position, the stored energy tending to return the deflected portion of the member to the normal position, (iv) a control electrode monolithically formed with the substrate and the member, the electrode being spaced from the member along the direction of deflection of the portion of the member out of the normal position, the control electrode and the member being capable of having impressed therebetween a control signal sufficient to produce a field therebetween to deflect the portion of the member cut of its normal position so as to vary the capacitance of the capacitor, and (v) means for applying the input signal to the capacitor.

2. A capacitor as in claim 1, wherein:
the mounting means comprises a compliant facility centrally supporting the member.

3. A capacitor as in Claim 2, wherein:
the compliant facility is a membrane.

4. A capacitor as in Claim 3, wherein:
the membrane is an elastomer.

5. A capacitor as in Claim 3, wherein:
the membrane is a conductive metal.

6. A capacitor as in claim 1, wherein:
the mounting means comprises a compliant facility integrally formed with the member and the input-signal-applying means.

7. A capacitor as in Claim 6, wherein:
deflection of the portion of the member comprises rotation of the member about an axis which is asymmetric relative to the member.

8. A capacitor as in Claims 6, wherein:
deflection of the portion of the member comprises rotation of the member about an axis which is symmetric relative to the member.

9. A capacitor as in Claim 6, wherein:
deflection of the portion of the member comprises rotation of the member about an axis, and the field is bounded by the control electrode and the portion of the member, the portion being spaced from the axis.

10. A capacitor as in Claim 9, wherein:
the axis is symmetric relative to the member.

11. A capacitor as in Claim 9, wherein:
the axis is asymmetric relative to the member.

12. A capacitor as in Claim 6, wherein:
the compliant facility includes a torsion spring.

13. A capacitor as in Claim 6, wherein:
the compliant facility is a cantilever spring.

14. A capacitor as in Claim 6, wherein:
the compliant facility comprises a membrane.

15. A capacitor as in Claim 14, wherein a portion of the membrane comprises a part of the member.

16. A capacitor as in Claim 15, wherein:
the member moves in a piston-like fashion as the portion thereof is deflected toward and away from the substrate.

17. A capacitor as in Claim 16, wherein:
the member and the membrane are integral, the membrane having high compliance and the member having low compliance.

18. A capacitor as in Claim 17, wherein:
the member is smaller than and is generally centrally located with respect to the membrane.

19. A capacitor as in Claim 6, wherein:
the compliant facility comprises a flexure system made up of a plurality of cantilever-torsion springs.

20. A capacitor as in Claim 19, wherein:
the member moves in a piston-like fashion as the portion thereof is deflected toward and away from the substrate.

21. A capacitor as in Claim 6, wherein:
the complaint facility comprises means for permitting the member to move in piston-like fashion as the portion thereof is deflected toward and away from the substrate.

22. A capacitor as in Claim 6, wherein:
the mounting means further comprises:
an insulative spacer on the substrate and monolithically formed with the substrate, the member and the control electrode, the spacer supporting the compliant facility.

23. A capacitor as in Claim 2, wherein:
the insulative spacer defines a portion of a boundary of a well into and out of which the portion of the member moves as it deflects toward and away from the substrate.

24. A capacitor as in claim 23, wherein:
he spacer is a photoresist.

25. A capacitor as in claim 6, wherein:
the mounting means further comprises an electrically conductive post on the substrate and monolithically formed with the substrate, the member and the control electrode, the post supporting the compliant facility.

26. A capacitor as in Claim 25, wherein:
the post defines a portion of a boundary of a well into and out of which the portion of the member moves as it deflects toward and away from the substrate.

27. A capacitor as in Claim 26, wherein:
the member and the compliant facility are electrically conductive, the post being electrically continuous with the member via the compliant facility, and the post is electrically insulated from the substrate.

28. A capacitor as in Claim 1, wherein:
the control electrode comprises a region of the substrate.

29. A capacitor as in Claim 28, which further comprises:
means for applying the control signal between the substrate region and the member, and the input-signal-applying means includes a conductive input path and a conductive output path both electrically continuous with the member so that the input signal passes through the portion of the member.

30. A capacitor as in claim 29, wherein:
the control-signal-applying means comprises the substrate region, and one of the conductive paths electrically continuous with the member.

31. A capacitor as in Claim 30, wherein:
the substrate region is grounded.

32. A capacitor as in Claim 31, wherein:
the input signal is time-varying, and the frequency of the control signal is substantially less than that of the input signal.

33. A capacitor as in Claim 32, wherein:
the control signal is substantially non-time-varying.

34. A capacitor as in Claim 33, wherein:
the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto.

35. A variable capacitor which includes the capacitor of Claim 32, wherein:
the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto, and the frequency of the control signal is sufficiently low with respect to the resonant frequency of the member so that the portion of the member deflects substantially in synchronism therewith.

36. A capacitor as in Claim 30, wherein:
the input signal and the control signal are superimposed.

37. A capacitor as in Claim 1, which further comprises:
an electrically insulative dielectric layer on the substrate for supporting the control electrode on, and insulating it from, the substrate.

38. A capacitor as in Claim 37, which further comprises:
means for applying the control signal between the control electrode and the member, and the input-signal-applying means includes a conductive input path electrically continuous with the member and a conductive output path spaced from the member along the direction of deflection of the portion of the member, the output path being supported on and insulated form the substrate so that the input signal is applied by the portion of the member, acting as one plate of the capacitor, to the output path acting as the other plate of the capacitor.

39. A capacitor as in Claim 38, wherein:
the control-signal-applying means comprises the control electrode, and the conductive input path.

40. a capacitor as in claim 39, wherein:
the input signal is time-varying, and the frequency of the control signal is substantially less than that of the input signal.

41. A capacitor as in Claim 40, wherein:
the control signal is substantially non-time-varying.

42. A capacitor as in claim 41, wherein:
the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto.

43. A variable capacitor which includes the capacitor of Claim 40, wherein:
the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto, and the frequency of the control signal is sufficiently low with respect to the resonant frequency of the member so that the portion of the member deflects substantially in synchronism therewith.

44. A capacitor as in Claim 38, wherein:
the input signal and the control signal are superimposed.

45. A capacitor as in Claim 1, wherein:
the substrate comprises a material selected from the group consisting of semiconductors, ceramics, aluminas, diamond and quartz.

46. A capacitor as in Claim 37, wherein:
the substrate is a semiconductor, and the dielectric layer is made of a material selected from the group consisting of an insulative oxide, an insulative nitride and a polymer.

47. A capacitor as in Claim 46, wherein:
the semiconductor is silicon or gallium-arsenide, the insulative oxide is a silicon oxide, the insulative nitride is a silicon nitride, and the polymer is an epoxy or an acrylate.

48. A capacitor as in Claim 46, wherein:
the output path is supported on and insulated from the substrate by the dielectric layer.

49. A capacitor as in Claim 1, which further comprises:
means for preventing the member from touching the control electrode when the portion of the member moves toward the sub-strate.

50. A capacitor as in Claim 1, wherein:
the member is generally planar, and the mounting means mounts the member for generally coplanar, translational movement of substantially the entire member.

51. A capacitor as in Claim 50, which further comprises:
a membrane, one portion of which comprises a part of the mounting means and another portion of which comprises a part of the member.

52. A capacitor as in Claim 50, wherein:
the member is a substantially rigid plane, and the mounting means is a flexure system made up of a plurality of cantilever-torsion springs.

53. A capacitor as in Claim 1, wherein:
the member is generally planar, and the mounting means mounts the member for generally rotational movement about an axis remote from the centroid of the member.

54. A capacitor as in Claim 53, wherein:
the mounting means is a torsion spring.

55. A capacitor as in claim 53, wherein:
the mounting means is a cantilever spring.

56. An electrical circuit which includes the capacitor of Claim 1 and wherein:
the input-signal-applying means comprises means for grounding the substrate, and means for connecting the member to a node of the circuit so that the voltage to ground on the node is applied to the member, whereby the capacitor is in shunt with the node.

57. All electrical circuit which includes the capacitor of Claim 1 and wherein:
the input-signal-applying means comprises means for connecting the member to a first node of the circuit so that current into the first node is applied to the member, and means for connecting the substrate to a second node so that current out of the second node flows from the substrate, whereby the capacitor is in series with the nodes.

58. An electrical circuit which includes the capacitor of Claim 1 and which further comprises:
means for applying to the control electrode a control signal independent of the capacitor-affected input signal.

59. An electrical circuit which includes the capacitor of Claim 1 and which further comprises:
means for applying to the control electrode a control signal derived from the capacitor-affected input signal.

60. A capacitor as in Claim 1, wherein:
selected characteristics of the compliant facility are alterable so that the movement of the portion of the member and, hence, the capacitance of the capacitor, both of which are effected by the application of a selected control signal to the control electrode, are adjustable.

61. A capacitor as in Claim 60, wherein:
characteristic-alteration of the compliant facility is achievable by selective removal of a portion of the compliant facility.

62. A capacitor as in Claim 61, wherein:
selective material removal is achievable by selective application of concentrated radiant energy to the compliant facility.

63. A capacitor as in Claim 1, wherein:
the control electrode is a section of the substrate.

64. A capacitor as in Claim 1, wherein:
the control electrode is a conductive region formed on the substrate.

65. A capacitor as in Claim 64, wherein:
the conductive region is insulated from the substrate.

66. A transmission line which includes one or more capacitors according to Claim 1 for varying the impedance thereof.

67. A transmission line as Claim 66 of the variable impedance, microstrip type.

68. An impedance matching network which includes one or more capacitors according to Claim 1 for varying the impedance thereof.

69. A filter network which includes one or more capacitors according to Claim 1 for varying the impedance thereof.

70. An antenna which includes one or more capacitors according to Claim 1 for varying the impedance and the frequency characteristics thereof.

71. An antenna as in Claim 70, wherein:
the member is an element of the radiating or receiving surface of the antenna.

72. An antenna as in Claim 71 of the patch type.

73. An antenna as in Claim 71 of the spiral type.

74. An antenna as in Claim 71 of the slot type.

75. A coupler which includes one or more of the capacitors according to Claim 1 for varying the impedance thereof.

76. A coupler as in Claim 75 of the symmetric type.

77. A coupler as in Claim 75 of the asymmetric type.

78. A coupler as in Claim 75 of the rat race type.

79. A waveguide having at least one surface which comprises one or more of the capacitors according to Claim 1 for varying the impedance thereof.

80. A FIN line including one or more of the capacitors according to Claim 1 for varying the impedance thereof.

81. A capacitor as in Claim 1, wherein:
the normal position of the member is away from the substrate and when the member is detected it is closer to the substrate.

82. A capacitor as in Claim 1, wherein:
the normal position of the member is toward the substrate and when the member is deflected it is farther from the substrate.

83. A microminiature, monolithic, variable electrical capacitor for affecting an input signal, which comprises:
(i) a substrate, (ii) a member monolithically formed with and spaced from the substrate, a region of the substrate and a portion of the member acting as the respective plates of the capacitor, (iii) means for mounting the member for deflection of the portion thereof toward and away from the substrate region and for storing energy when the portion of the member deflects out of a normal position, the stored energy tending to return the deflected portion of the member to the normal position, (iv) means for selectively deflecting the portion of the member out of its normal position to vary the capacitance of the capacitor, and (V) means for applying the input signal to the capacitor.

84. A capacitor as in Claim 83, wherein:
the selective deflecting means includes means for producing an electric field bounded in part by the portion of the member, the electric field deflecting the portion of the member relative to the substrate by an amount proportional to the magnitude thereof.

85. A capacitor as in Claim 84, wherein:
the electric field is produced by a voltage having a frequency such that the portion of the member defects substantially in synchronism therewith.

86. A capacitor as in Claim 85, wherein:
the voltage is substantially non-time-varying.

87. A capacitor as in Claim 84, wherein:
the deflection field produced by the field-producing means is bounded in part by the region of substrate.

88. A capacitor as in Claim 87, wherein:
the deflection field is produced by a voltage having a frequency such that the portion of the member deflects substantially in synchronism therewith.

89. A capacitor as in Claim 88, wherein:
the voltage is substantially non-time-varying.

90. A capacitor as in Claim 89, wherein:
the deflection voltage is applied between the substrate and the member.

91. A capacitor as in Claim 90, wherein:
the input signal is a voltage having a frequency which is sufficiently high with respect to the resonant frequency of the member such that the portion of the member is incapable of deflecting in response thereto.

92. A capacitor as in Claim 91, wherein:
the input voltage is superimposed on the deflection voltage.

93. A capacitor as in Claim 92, wherein:
the field-producing means include a control electrode associated with the substrate region, which electrode in part bounds the electric field which deflects the portion of the member by an amount determined by the magnitude thereof.

94. A capacitor as in Claim 93, wherein:
the electric field is produced by a voltage applied to the control electrode and having a frequency such that the portion of the member deflects substantially in synchronism therewith.

95. A capacitor as in Claim 94, wherein:
the deflection voltage is substantially non-time-varying.

96. A capacitor as in Claim 95, wherein:
the deflection voltage is applied between the control electrode and the member and the input voltage is applied to the member.

97. A capacitor as in Claim 96, wherein:
the control electrode and the mounting means are monolithically formed with the substrate and the member.

98. A capacitor as in Claim 97, wherein:
the mounting means comprises a deformable membrane on which the member resides, and a support on the substrate to which the membrane is attached.

99. A capacitor as in Claim 98, wherein:
the member comprises a low compliance, generally rigid element residing on the membrane, portions of the membrane surrounding the member having high compliance.

100. A capacitor as in Claim 99, wherein:
the member and the membrane are electrically conductive and integral and the member is substantially thicker than the membrane.

101. A capacitor as in Claim 100, wherein:
the support is a conducive post on and insulated from the substrate.

102. A capacitor as in Claim 100, wherein:
the support is an insulative spacer on the substrate.

103. A variable capacitor of the type set forth in Claim 83, wherein:
the selective deflecting means deflects the portion of the member with respect to time, the frequency of such deflection being independent of the frequency of the input signal.

104. A variable capacitor as in Claim 103, wherein:
the frequency of the deflection is smaller than the frequency of the input signal.

105. A non-linear capacitor of the type set forth in Claim 83, wherein:
the selective deflecting means deflects the portion of the member with respect to time, the frequency of such deflection being substantially the same as the frequency of the input signal.

106. A non-linear capacitor as in Claim 105, wherein:
the selective deflecting means is the input signal-applying means.

107. A microminiature, monolithic, variable electrical capacitor for affecting an input signal, which comprises:
(i) a substrate, (ii) a microminiature member monolithically formed with and spaced from the substrate, (iii) an electrically conductive region spaced from a portion of the member, the region and the portion of the member acting as the respective plates of a parallel plate capacitor, (iv) means for mounting the member for deflection of the portion thereof toward and away from the region and for storing energy when the portion of the member deflects out of a normal position toward the region, the stored energy tending to return the deflected portion of the member to the normal position, (v) means for selectively deflecting the portion of the member out of its normal position toward the region to vary the capacitance of the capacitor, and (v) means for applying the input signal to the capacitor.

108. A capacitor as in Claim 103, wherein:
the deflecting means includes electric field-producing means for producing an electric field which deflects the member out of the normal position.

109. A capacitor as in Claim 103, wherein:
the field-producing means includes a control electrode which in part bounds the electric field which deflects the portion of the member toward the region by an amount proportional to the magnitude thereof.

110. A capacitor as in Claim 105, wherein:
the electric field is produced by a voltage applied to the control electrode and having a frequency such that the portion of the member deflects substantially in synchronism therewith.

111. A capacitor as in Claim 106, wherein:
the deflection voltage is substantially non-time-varying.

112. A capacitor as in Claim 107, wherein:
the deflection voltage is applied between the control electrode and the member and the input voltage is applied between the region and the member.

113. A capacitor as in Claim 108, wherein:
the control electrode and the region are substantially coplanar.

114. A capacitor as in Claim 109, wherein:
the control electrode and the region are formed on the substrate.

115. A capacitor as in Claim 110, wherein:
the control electrode and the region include respective interdigitated segments all of which are generally aligned with the portion of the member as it deflects.

116. A capacitor as in Claim 111, wherein:
the segments are insulated from each other and from the substrate.

117. A microminiature, monolithic device for affecting an electrical input signal in response to a control signal, which comprises:
a substrate, a movable member which in a first normal position affects the input signal in a first mode and which affects the input signal in a second mode when not in the first position, means for mounting the member at a location spaced from the substrate for movement of the member toward and away from the substrate and for storing energy when the member moves out of the first position, the stored energy biasing the member toward the first position, means for applying the input signal to the device, means for selectively applying a control signal to the member, and means responsive to the control signal for selectively moving the member out of the normal position to selectively alter the mode which the member affects the input signal.

118. A device as in Claim 117, wherein:
the member is electrically conductive and the application of the control signal thereto produces an electrostatic field acting thereon which moves the member out of the first position relative to the substrate.

119. A variable electrical capacitor which includes a device as in Claim 118, wherein:
the member is one plate of the capacitor, movement of the member by the electrostatic field altering the capacitance of the capacitor, and the input signal and the control signal are both applied to the member.

120. A capacitor as in Claim 119, wherein:
the path taken by the input signal is in parallel with the alterable capacitance of the capacitor.

121. A capacitor as in Claim 119, wherein:
the path taken by the input signal in series with the alterable capacitance of the capacitor.

122. A device as in Claim 118, wherein:
the electrostatic field moves the member toward the substrate.

123. A waveguide which includes the device of Claim 117, wherein:
the movable member forms a coplanar portion of the interior surface of the waveguide in the first position, movement of the member out of the first position being away from the wall to effectively decrease the cross-section of the waveguide along a line generally parallel to the line of movement of the member.

124. A variable capacitor which includes a device as in Claim 118, wherein:
the member is one plate of the capacitor, movement of the member altering the capacitance of the capacitor.

125. A capacitor as in Claim 124, wherein:
the capacitor is in parallel with the input signal.

126. A capacitor as in Claim 124, wherein:
the capacitor is in series with the input signal.

127. A variable capacitor of the type set forth in Claim 118 for use with a time-varying input signal, wherein:
the selective moving means moves the member with respect to time, the frequency of such movement being independent of the frequency of the input signal.

128. A variable capacitor as in Claim 127, wherein:
the frequency of the movement is smaller than the frequency of the input signal.

129. A non-linear capacitor of the type set forth in Claim 118 for use with a time-varying input signal wherein:
the selective moving means moves the member with respect to time, the frequency of such movement being substantially the same as the frequency of the input signal.

130. A non-linear capacitor as in Claim 129, wherein:
the selective moving means is the input signal-applying means