WO2016127822A1

WO2016127822A1 - Fully-integrated anti-blocking radio frequency receiving front-end architecture

Info

Publication number: WO2016127822A1
Application number: PCT/CN2016/072557
Authority: WO
Inventors: 吴建辉; 程超; 于天骥; 姚红燕; 程康; 陈超; 李红; 黄成�
Original assignee: 东南大学
Priority date: 2015-02-10
Filing date: 2016-01-28
Publication date: 2016-08-18
Also published as: CN104617970A; CN104617970B

Abstract

Disclosed is a fully-integrated anti-blocking radio frequency receiving front-end architecture, comprising a blocking signal filtering stage and a down mixing stage. The blocking signal filtering stage is a feed-forward structure, and a main branch and a feed-forward branch use low-noise amplifiers with same circuit structures to realize matching. In addition, the feed-forward branch uses the impedance moving feature of a passive mixer in the frequency domain, a band elimination filter is generated at a radio frequency local oscillator to filter useful signals, and then a useful radio frequency signal is obtained by subtracting an obtained blocking signal from a blocking signal of the main branch. Because the blocking signal is directly filtered out after two low-noise amplifiers, influence on another circuit is avoided, and other non-ideal factors are avoided. Down mixing is realized to obtain a useful middle-frequency signal by connecting the passive mixer.

Description

A fully integrated anti-blocking RF receiving front-end architecture

Technical field

The invention belongs to the field of wireless communication receivers and relates to a fully integrated anti-blocking RF receiving front-end architecture.

Background technique

Infinite communication technology is now widely used, but due to the limited nature of spectrum resources, there are a large number of users in the public frequency band. Like 2.4GHz, the ISM band shared by all countries, so wireless networks such as wireless LAN, Bluetooth, and ZigBee all work in the 2.4GHz band. The strong transmit signal of the transmitter is a blocking signal for other receivers in nearby channels in the desired frequency band. A large blocking signal can shift the operating state of the transistor in the receiver, causing the receiver's gain to drop, noise figure and linearity to deteriorate, and even the receiver can not work. In order to eliminate the impact of the blocking signal on the overall circuit of the receiver, it needs to be eliminated from the point RF front end at the front end of the receiver.

At present, internationally renowned communication semiconductor companies such as American Broadcom, European Microelectronics Research Center and Cornell University, Microelectronics Research Center and University have conducted research on the fully integrated anti-blocking RF receiving front-end, and have achieved certain results. However, the existing fully integrated anti-blocking RF receiving front-end has obvious shortcomings. Broadcom's feedforward and feedback structure uses the mixer's mixing function to move the low-IF high-pass filter to the RF local oscillator to form the RF band stop. Filter, such a structure not only does the two branches not match, but also the blocking signal passes through the lower mixer in the feedforward branch and the high-pass filter in the low intermediate frequency, which deteriorates the linearity, causing gain compression and deterioration. Noise Figure. The European Microelectronics Research Center's voltage-mode fully integrated anti-blocking RF receiver front-end architecture is highly demanding because it is directly in voltage form. In order to ensure linearity, the research center's results used a 2.5V LNA with a supply voltage. Cornell University's LNA-less structure has good linearity, but its noise performance is poor, and the isolation effect is poor. The local oscillator signal is easy to leak into the antenna and deteriorate the frequency domain resource environment.

Summary of the invention

Technical Problem: The present invention proposes a fully integrated anti-blocking RF receiving front-end architecture that solves the impact of blocking signals on a receiver in a frequency domain environment.

Technical Solution: The fully integrated anti-blocking RF receiving front-end architecture of the present invention includes a radio frequency blocking signal filtering stage And a downmixing stage, the RF blocking signal filtering stage comprising a first low noise amplifier, a second low noise amplifier, a subtraction circuit and a load stage, the first low noise amplifier being connected to a differential end of the subtraction circuit The second low noise amplifier is connected to another differential end of the subtraction circuit, and the second low noise amplifier is also connected to the load stage. The RF band rejection filter stage is connected to the downmix stage through the output of the subtraction circuit.

In a preferred embodiment of the present invention, the load stage is connected by a second passive switching mixer and a second transimpedance amplifier, and an input end of the second passive switching mixing stage and an output end of the second low noise amplifier connection.

In a preferred embodiment of the invention, the output of the subtraction circuit is also connected to an LC load network.

In a preferred embodiment of the present invention, the downmixing stage includes a first transconductance amplifier, a first passive switching mixer, and a first transimpedance amplifier that are sequentially connected.

In a preferred embodiment of the invention, the output frequency response curve of the first low noise amplifier exhibits an all-pass characteristic, and the output frequency response curve of the second low noise amplifier and the load stage exhibits a band-stop characteristic. Using the impedance shifting characteristics of the passive mixer, the IF impedance high-pass characteristic of the transimpedance amplifier is moved to the RF local oscillator to form an RF band-stop filter. The feedforward structure is used to subtract the output of the RF band rejection filter from the output of the low noise amplifier to realize the subtraction of the two signals to obtain the RF useful signal. The down-converter is down-converted to obtain an intermediate frequency useful signal.

The RF receive front end architecture includes a blocking signal filtering stage and a down mixing stage. The blocking signal filtering stage is a feedforward structure comprising a first low noise amplifier, a second low noise amplifier, a second passive switching mixer, a second transimpedance amplifier, L1 and C1. The first low noise amplifier of the main branch is identical to the second low noise amplifier of the feedforward branch, achieving a high degree of matching of the two branches. The second low noise amplifier, the second passive switching mixer, and the second transimpedance amplifier form a passive mixer. Since the passive mixer has a shifting characteristic in the frequency domain, the input impedance characteristic of the second transimpedance amplifier is moved to the local oscillator frequency by the second passive switching mixer, and the output of the second low noise amplifier The end filters the wanted signal and retains the blocking signal. The output components of the first low noise amplifier and the second low noise amplifier are subtracted to obtain a radio frequency useful signal, and the blocking signal is filtered out. The architecture directly filters the blocking signal after passing through the first low noise amplifier and the second low noise amplifier without introducing it into other circuit modules, resulting in more non-ideal factors. The LC network acts as a load, and the inductance resonates with the parasitic capacitance at that point to reduce leakage of the RF useful current signal. The downmixing stage is a passive mixer comprising a first transconductance amplifier, a first passive switching mixer and a first transimpedance amplifier, which are converted into an RF useful current signal by the first transconductance amplifier, first The source switching mixer modulates it to obtain an intermediate frequency useful current signal, and the first transimpedance amplifier converts the intermediate frequency useful current signal into an intermediate frequency useful voltage signal. Because passive mixers have the advantages of linearity and noise figure performance over traditional active mixers, passive mixers can improve the performance of the RF front end.

Advantageous Effects: Compared with the prior art, the present invention has the following advantages:

The main branch of the invention utilizes a passive mixer to shift the impedance at a frequency, and the switching mixer stage and the transimpedance level of the passive mixer are used as a low-noise load, and are mixed through the switch of the working linear region. The frequency converter moves the input impedance of the intermediate frequency high-pass impedance characteristic of the transimpedance amplifier to the RF local oscillator to form an RF band rejection filter. The feedforward branch filters out the RF wanted signal while preserving the RF blocking signal. The main branch uses the same low noise level as the feedforward branch. The RF useful signal is obtained by subtracting the two branches. The RF band-stop filter in the existing feedforward anti-blocking RF receiving front end is formed by up- and down-converting the intermediate frequency high-pass filter through the upper and lower mixers. Since the image noise needs to be eliminated during the up-and-down conversion process, the main branch requires two paths of I and Q. Therefore, compared with the prior art, the present invention does not require the I and Q two-way up-and-down mixers and the intermediate frequency high-pass filter, and has a simple circuit structure, saves circuit area and power consumption, and is low in the two branches. The noise is the same and the matching is good. Since the blocking signal is directly eliminated behind the RF transconductance amplifier and does not affect other circuits, the linearity of the intermediate frequency is not high. In addition, the low noise amplifier can achieve good isolation, and the local oscillator signal is difficult to leak to the antenna to deteriorate the spectrum environment.

DRAWINGS

1 is a schematic diagram of an RF receiving front end structure of the present invention;

2 is a functional simulation diagram of a radio frequency receiving front end of the present invention.

The figure includes: a first low noise amplifier LNA1, a second low noise amplifier LNA2, a first inductor L1, a first capacitor C1, a first transconductance amplifier Gm1, a first passive switching mixer Pmixer1, and a second passive switch. Mixer Mixer2, first transimpedance amplifier TIA1, second transimpedance amplifier TIA2, local oscillator signal input terminal LO, subtraction circuit S, signal input terminal RFIN, and signal output terminal IFOUT.

detailed description

The invention will now be further described in conjunction with the embodiments and the drawings.

As shown in FIG. 1 , the fully integrated anti-blocking RF receiving front-end architecture proposed by the present invention is a feedforward structure, which is formed by connecting a RF blocking signal filtering stage and a down mixing frequency stage, and the RF blocking signal filtering stage filters the RF blocking signal. While the radio frequency useful signal is reserved, the downmix frequency stage converts the radio frequency useful signal into an intermediate frequency useful signal. The RF blocking signal filtering stage includes a first low noise amplifier LNA1, a second low noise amplifier LNA2, a subtraction circuit S, and a load stage. The main branch is composed of a first low noise amplifier LNA1, and the feedforward branch is composed of a second low noise amplifier LNA2, a subtraction circuit S and a load stage. The load stage is connected by a second passive switching mixer Mixer2 and a second transimpedance amplifier TIA2, and the second passive switching mixer Mixer2 will be a second transimpedance The intermediate frequency high-pass characteristic curve of the input impedance of the amplifier TIA2 is moved to the RF local oscillator to form an RF band-stop characteristic. The passive mixer has a shifting characteristic on the impedance in frequency, and a radio frequency band rejection filter is formed in the feedforward branch of the RF blocking signal filtering stage. The first low noise amplifier LNA1 of the main branch is an all-pass RF amplifier. The main branch output stage is connected to a differential end of the subtraction circuit S, and the feedforward branch output stage is connected to another differential end of the subtraction circuit S. The radio frequency component (including the radio frequency blocking signal and the radio frequency useful signal) of the main branch is subtracted from the radio frequency blocking signal of the feedforward branch by the subtraction circuit S, and the radio frequency band pass filter is realized, and the radio frequency blocking signal is filtered to obtain the radio frequency. Useful signal. The output of the subtraction circuit S is also connected to an LC load network to increase the Q value of the RF bandpass filter. The specific connection relationship is: the input ends of the first low noise amplifier LNA1 and the second low noise amplifier LNA2 are connected to the radio frequency input end, and the output ends are respectively connected to one input end of the subtraction circuit S; the second low noise amplifier LNA2 The output terminal is simultaneously connected to the input end of the second passive switching mixer Mixer2; the output end of the second passive switching mixer Mixer2 is connected to the input end of the second transimpedance amplifier TIA2; the LC network is used as the subtraction circuit S The load, the negative terminal of the first inductor L1 and the negative terminal of the first capacitor C1 are connected to the output terminal of the subtraction circuit S, and the positive terminal of the first inductor L1 and the positive terminal of the first capacitor C1 are connected to the power supply voltage.

The down mixing stage includes a first transconductance amplifier Gm1, a first passive switching mixer Pmixer1, and a first transimpedance amplifier TIA1 that are sequentially connected. The first transconductance amplifier Gm1 converts the radio frequency useful voltage signal obtained from the RF blocking signal filtering stage into a radio frequency useful current signal, and the first passive switching mixer Pmixer1 modulates the radio frequency useful current signal into an intermediate frequency useful current signal, and then A transimpedance amplifier TIA1 is converted to an intermediate frequency useful voltage signal. The specific connection relationship is: the input end of the first transimpedance amplifier TIA1 is connected to the output end of the subtraction circuit S, and the output end is connected to the input end of the first passive switching mixer Mixer1; the first passive switching mixer The output of Pmixer1 is connected to the input of the first transimpedance amplifier TIA1; the output of the first transimpedance amplifier TIA1 is connected to the intermediate frequency output.

FIG. 2 is a functional simulation diagram of the RF receiving front end of the present invention. As can be seen from the figure, the RF front end achieves 20 dB suppression for the blocking signal outside the 40 MHz bandwidth.

The above-described embodiments are merely preferred embodiments of the present invention, and it should be noted that those skilled in the art can make several improvements and equivalents without departing from the principles of the present invention. The technical solutions required for improvement and equivalent replacement are all within the scope of the present invention.

Claims

A fully integrated anti-blocking RF receiving front-end architecture is characterized in that the architecture is a feedforward structure, which is formed by connecting a radio frequency blocking signal filtering stage and a down mixing frequency level, and the radio blocking signal filtering stage includes a first low a noise amplifier (LNA1), a second low noise amplifier (LNA2), a subtraction circuit (S), and a load stage, the first low noise amplifier (LNA1) being coupled to a differential terminal of the subtraction circuit (S), The second low noise amplifier (LNA2) is connected to another differential end of the subtraction circuit, and the second low noise amplifier (LNA2) is also connected to the load stage, and the RF band rejection filter stage is passed through the output of the subtraction circuit (S). Downmix level connection.
The fully integrated anti-blocking RF receiving front-end architecture according to claim 1, wherein the load stage is connected by a second passive switching mixer (Pmixer 2) and a second transimpedance amplifier (TIA2), The input of the second passive switching mixer (Pmixer 2) is connected to the output of the second low noise amplifier (LNA2).
The fully integrated anti-blocking RF receiving front-end architecture according to claim 1 or 2, wherein the output of the subtraction circuit (S) is further connected to an LC load network.
The fully integrated anti-blocking RF receiving front-end architecture according to claim 1 or 2, wherein the down-mixing stage comprises a first transconductance amplifier (LNA1) and a first passive switching mixer ( Pmixer1) and the first transimpedance amplifier (TIA1).
The fully integrated anti-blocking RF receiving front-end architecture according to claim 1 or 2, wherein an output frequency response curve of said first low noise amplifier (LNA1) exhibits an all-pass characteristic, said second low noise amplifier ( The output frequency response curve of LNA2) and the load stage exhibits a band-stop characteristic.