CA2340951A1 - Resonance elimination in high speed packages - Google Patents

Resonance elimination in high speed packages Download PDF

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Publication number
CA2340951A1
CA2340951A1 CA002340951A CA2340951A CA2340951A1 CA 2340951 A1 CA2340951 A1 CA 2340951A1 CA 002340951 A CA002340951 A CA 002340951A CA 2340951 A CA2340951 A CA 2340951A CA 2340951 A1 CA2340951 A1 CA 2340951A1
Authority
CA
Canada
Prior art keywords
microwave
accordance
package
microwave package
absorber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002340951A
Other languages
French (fr)
Inventor
Mindaugas F. Dautartas
John M. Geary
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agere Systems LLC
Original Assignee
Agere Systems Guardian Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agere Systems Guardian Corp filed Critical Agere Systems Guardian Corp
Publication of CA2340951A1 publication Critical patent/CA2340951A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01PWAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00Auxiliary devices
    • H01P1/16Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H01P1/162Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion absorbing spurious or unwanted modes of propagation

Abstract

An optical microwave package eliminates launching electrical modes into a microwave strip-line by forming a moat in a housing portion of the package to suppress microwave resonant energy. The moat can be filled with a conductive material to further suppress package resonances. Additionally, the bottom of a substrate positioned within the housing is isolated from any conductive metal to further suppress microwave resonant energy.

Description

Dautartas 71-16 1 RESONANCE ELIMINATION IN HIGH SPEED PACKAGES
This application claims priority of U. S. provisional application serial No.
60/190,833, filed on March 21,2000.
Field of the Invention s This invention relates to microelectronics, and specifically to microwave frequency optical packages.
Background of the Invention Microwave resonance in high-speed packages sometimes degrades the performance of the packages by deleteriously increasing the return loss of electrical signals fed into the to package. The conventional approach to reduce the microwave resonance is to introduce thick sheets of resistive polymers, far from the launch site, onto the walls or lid of the packages to absorb microwaves after they are generated. However, with communication frequencies constantly increasing, this approach is insu:f~icient to achieve the decrease in return loss desired, particularly at a time when the miicrowave spectrum technology is 15 extending from 1 to 40 GHz and above.
Summary of the Invention A microwave package includes a housing havin;~ a moat formed in the housing to suppress microwave resonant energy. The moat may be filled with microwave absorbent material to further suppress microwave resonant energ;r.
2o Brief Description of the Drawings The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice in the semiconductor industry, the various features of the drawing are not to scale.
On the contrary, the dimensions of the various features are arbitrarily expanded or reduced 25 for clarity. Included in the drawing are the following fil;ures:
Figure 1 is an isometric view of a housing in which a microwave component is placed, in accordance with an embodiment of the present invention;

Dautartas 71-16 Figure 2 is a cross sectional view of a microwave device having a moat, with an isolated substrate;
Figure 3 is a cross sectional view of a microwave device having a moat, in accordance with the present invention; and Figure 4 is a three dimensional view of a microwave component coupled to optical fibers.
Detailed Description An exemplary embodiment of the invention includes a package having a moat in the package body filled with a conductive material having a sheet resistance of approximately 20 ohmslsquare, to reduce the resonance in a 40 GHz; optical microwave package and reduce the return loss to -10 dB or better.
Referring now to the drawings, wherein like reference numerals refer to like elements throughout, Figure 1 is an isometric view of a housing 6, in which a microwave component, such as an electro-absorptive modulator :16, a high speed receiver, or any appropriate optoelectric device, is placed. Housing 6 comprises a moat 2, and a ledge 4 for securing the microwave component 16. Moat 2 is formed in the walls of housing 6.
Although not visible in the perspective view shown in Figure l, another moat 2 is also formed in wall 7 of housing 6.
Figure 3 is a cross sectional view of a microwave package 22 having a moat 2, in 2o accordance with an embodiment of the present invention. Moat 2 is formed in the housing 6 and may also be filled with a microwave absorber 24. 'The inventors have discovered that using a resistive semiconductor like silicon in the moat suppresses and absorbs these microwave resonances without appreciably degrading the electrical coupling efficiency.
Germanium, polycrystalline silicon, single-crystal silicon, gallium arsenide, monolithic doped silicon, or a single crystal semiconductor may be used as the microwave absorber 24.
Improved electrical performance is obtained by using a resistive semiconductor material in the moat 2 that is monolithic, as opposed to the polymer pastes and sheets of Dautartas 71-16 the prior art, has a good coefficient of thermal expansion to match the dielectric substrate, has a good thermal conductivity, and can be easily modified to accommodate a variety of packaging schemes. It is also envisioned that alternative microwave absorbing materials, such as resistive ceramic susceptors, compressed iron powder and carbon may be used.
s The relative positioning of housing 6 and the microwave device 22 shown in Figure 3 is such that edge 20 is coupled to ledge 4. Optical energy is coupled to the exemplary microwave component 16 by optical fiber 18. In the embodiment of the invention depicted in Figure 3, the device I6 is mounted on a submount 8, which may be formed of beryllium oxide (Be0), aluminum oxide, or the like. The submount 8 is in turn coupled to to thermoelectric cooler (TEC) 14. The inventors have discovered that forming a moat 2 in the housing 6 suppresses microwave resonant energy. It has been calculated that a return loss of less than -IOdB is attainable.
Note that the thermoelectric cooler 14 may not always be required, depending upon the amount of heat that needs to be removed.
15 Figure 2 is a cross sectional view of a variation of the exemplary microwave package 22 having an isolated substrate 8 and a moat 2. In the variation of FIG. 2, a microwave absorber 10 is introduced into the cavity where the microwaves may be generated. The dielectric substrate is sufficiently thick such that electrical fields in the planar waveguide are not appreciably attenuated; yet the resonances are reduced. The 20 optimal thickness may easily be determined experimentally for a given package configuration. Note that some embodiments of thc~ present invention suppress the formation of microwave resonances at the point of generation, in contrast to prior attempts to absorb the microwaves further away from the launch site.
In Figure 2, the electro-absorptive (EA) modul'.ator 16 is mounted to a dielectric 25 submount or substrate 8. The dielectric submount 8 provides electrical isolation between the active microwave component 16 and the housing 6 and may be made of a ceramic such as Be0 or aluminum oxide, for example. Also, when used with high-power microwave devices, the dielectric substrate performs the function of a heat spreader. It is then Dautartas 71-16 advantageous that the dielectric substrate be made of a material with high thermal conductivity such as beryllium oxide or aluminum nitride. In the variation of Figure 2, the dielectric substrate 8 is bonded to an electrically resistive semiconductor 10, which is also bonded to a thermoelectric cooler (TEC) 14. Bonding may be done by soldering to metallized surfaces (not shown) on the dielectric substrate 8 and the electrically resistive silicon 10, use of adhesives, and the like.
The electrically resistive semiconductor 10 may be formed from the same material as the microwave absorber 2, described above. Alternatively, a different electrically resistive semiconductor may be used.
i o Figure 4 is a three dimensional view of an exemplary microwave device coupled to optical fibers. Optical fibers 18 couple optical enerl;y to microwave component 16.
Microwave component 16 is positioned within housing fi via a structure which is positioned within ledge 4.
While not completely understood, and not wishing to be bound to any theory, electrical modes launched into planar electrical wave-guides may inadvertently couple into strip-line modes in the dielectric substrate, the dielectric substrate forming a microwave cavity with the underside of the microwave device and any metal underneath the dielectric.
These modes are characterized by strong resonances, which markedly degrade the performance of the device by increasing return loss to greater than -10 dB, which is 2o required for some systems. These modes can be calculated and measured.
The present invention is applicable to 40 GHz el.ectro-absorptive modulators, high-speed receivers and other high-speed optoelectronic devices, for example. Note that while optical microwave packages are described as an embodiment herein, the present invention, and the passive electrically resistive semiconductor, also find applicability in conventional microwave packages.
It has been demonstrated that an optical microwave package containing an electro-absorptive modulator mounted on a beryllium oxide nnount, bonded to a thermoelectric cooler, operating at 40 GHZ, exhibits a return loss of -4 to -5 dB. The inventors have Dautartas 7I-1G
discovered that an optical package constructed with a 0.127 mm thick piece of silicon having a resistivity of 15-20 ohms/square interposed between a beryllium oxide mount and a thermoelectric cooler, with a moat filled with silicon having a resistivity of approximately 20 ohms/square, operating at 40 GHZ, exhibits a return doss better than (i.e., less than) -10 s dB.
It is emphasized that although the invention has been described with reference to illustrative embodiments, it is not limited to those embodiments. Rather, the appended claims should be construed to include other variants and embodiments of the invention that may be made by those skilled in the art without departing from the true spirit and scope of 1 o the present invention.

Claims (18)

1. A microwave package comprising a housing formed of a conductive material, said package having a moat formed therein to suppress microwave resonant energy.
2. A microwave package in accordance with claim 1, wherein said moat is filled with a microwave absorber.
3. A microwave package in accordance with claim 2, wherein said microwave absorber has a resistivity of approximately 20 ohms/sq.
4. A microwave package in accordance with claim 2, wherein said microwave absorber comprises resistive ceramic susceptors, compressed iron powder, or carbon.
5. A microwave package in accordance with claim 2, wherein the microwave absorber comprises a passive electrically resistive semiconductor.
6. A microwave package in accordance with claim 5, wherein the passive electrically resistive semiconductor comprises a material selected from the group consisting of germanium, polycrystalline silicon, single-crystal silicon, gallium arsenide, monolithic doped silicon, and a single crystal semiconductor.
7. A microwave package in accordance with claim 1 further comprising a dielectric substrate positioned within said housing, wherein a bottom of said substrate is isolated from said housing.
8. A microwave package in accordance with claim 7, wherein said dielectric substrate comprises beryllium oxide, aluminum nitride, or aluminum oxide.
9. A microwave package in accordance with claim 7, wherein said dielectric substrate is isolated from said conductive material by a microwave absorber.
10. A microwave package in accordance with claim 9, wherein said microwave absorber has a resistivity of approximately 20 ohms/sq.
11. A microwave package in accordance with claim 9, wherein said microwave absorber comprises resistive ceramic susceptors, compressed iron powder, or carbon.
12. A microwave package in accordance with claim 9, wherein the microwave absorber comprises a passive electrically resistive semiconductor.
13. A microwave package in accordance with claim 12, wherein the passive electrically resistive semiconductor comprises a material selected from the group consisting of germanium, polycrystalline silicon, single-crystal silicon, gallium arsenide, monolithic doped silicon, and a single crystal semiconductor.
14. A microwave package in accordance with claim 1 wherein the operating frequency is at least 40 GHz.
15. A microwave package in accordance with claim 1 wherein a microwave return loss is less than -10 dB.
16. A microwave package in accordance with claim 7 further comprising a microwave device mounted on said dielectric substrate.
17. A microwave package in accordance with claim 16, wherein said microwave component comprises an electro-absorptive modulator, a high-speed receiver, or a high-speed optoelectric device.
18. A microwave package in accordance with claim 16, further comprising a beryllium oxide submount withing the housing wherein the microwave devise is separated from the submount by the dielectric substrate.
CA002340951A 2000-03-21 2001-03-14 Resonance elimination in high speed packages Abandoned CA2340951A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US19083300P 2000-03-21 2000-03-21
US60/190,833 2000-03-21
US09/679,325 US6545573B1 (en) 2000-03-21 2000-10-04 Resonance elimination in high speed packages
US09/679,325 2000-10-04

Publications (1)

Publication Number Publication Date
CA2340951A1 true CA2340951A1 (en) 2001-09-21

Family

ID=26886502

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002340951A Abandoned CA2340951A1 (en) 2000-03-21 2001-03-14 Resonance elimination in high speed packages

Country Status (4)

Country Link
US (1) US6545573B1 (en)
EP (1) EP1137094A3 (en)
JP (1) JP2001343550A (en)
CA (1) CA2340951A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2840112A1 (en) * 2002-05-23 2003-11-28 Cit Alcatel ELECTRONIC MICROWAVE EQUIPMENT INCLUDING A METAL BOX FOR MITIGATION OF INTERFERENCE RESONANCES

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4575701A (en) * 1983-05-27 1986-03-11 The Marconi Company Ltd. Microwave switch
US4802178A (en) 1986-04-10 1989-01-31 Ortel Corporation High speed fiberoptic laser module
JPS63228801A (en) * 1987-03-18 1988-09-22 Fujitsu Ltd Microwave integrated circuit
JPH02202201A (en) * 1989-01-31 1990-08-10 Fujitsu Ltd Microwave unit
US5030935A (en) 1989-05-11 1991-07-09 Ball Corporation Method and apparatus for dampening resonant modes in packaged microwave circuits
US5260513A (en) * 1992-05-06 1993-11-09 University Of Massachusetts Lowell Method for absorbing radiation
JPH05326137A (en) * 1992-05-14 1993-12-10 Kanegafuchi Chem Ind Co Ltd Method of installing wave absorber for microwave oven
US5773151A (en) 1995-06-30 1998-06-30 Harris Corporation Semi-insulating wafer
DE19729671A1 (en) * 1997-07-11 1999-01-14 Alsthom Cge Alcatel Electrical circuit arrangement arranged in a housing
FR2776435B1 (en) * 1998-03-19 2000-04-28 Alsthom Cge Alcatel BIG GAIN AMPLIFIER
JPH11330288A (en) * 1998-05-08 1999-11-30 Mitsubishi Electric Corp Package for microwave

Also Published As

Publication number Publication date
EP1137094A3 (en) 2003-01-15
JP2001343550A (en) 2001-12-14
US6545573B1 (en) 2003-04-08
EP1137094A2 (en) 2001-09-26

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