A Simplified Image Rejection Down-Conversion Millimeter-Wave Link System and Its Spurious Suppression Method

Abstract

The present application discloses a simplified image rejection down-conversion millimeter-wave link system and a spurious suppression method. The system includes a millimeter-wave amplification module, a frequency multiplication amplification module, a down-conversion mixer, and a microwave intermediate-frequency amplification module. The output end of the millimeter-wave amplification module and the output end of the frequency multiplication amplification module are both connected to the input end of the down-conversion mixer, and the output end of the down-conversion mixer is connected to the input end of the microwave intermediate-frequency amplification module. The present application simplifies the image rejection down-conversion millimeter-wave link system, uses fewer components, reduces the complexity and cost of the system, and can achieve spurious suppression at a relatively low cost.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency communication technologies, and particularly to a simplified image frequency rejection down-conversion millimeter wave link system and a spurious suppression method thereof. Background Art

[0002] Millimeter waves refer to electromagnetic waves with frequencies ranging from 30 GHz to 300 GHz. Due to its rich spectrum resources and the carrier bandwidth of up to several hundred megahertz that it can provide, this frequency band shows great potential in the high-speed transmission of communication data. The millimeter wave band has been widely studied and applied in multiple fields such as anti-collision radars, high-resolution imaging, and ultra-wideband communication. A millimeter wave broadband down-conversion link system can down-convert millimeter wave high-frequency signals in a wide frequency band range to the microwave low-frequency band, and use a relatively mature microwave low-frequency band backend system to process the signals, thereby realizing the processing and analysis of millimeter wave high-frequency band broadband signals. The millimeter wave broadband down-conversion link system has extremely important application value in test instrument spread spectrum systems and millimeter wave broadband radar scanning systems, which is related to the performance of the entire machine system.

[0003] Currently, a published journal paper "50 GHz - 110 GHz Broadband Signal Down-Conversion Technology", School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Shenzhen Advanced Institute of the University of Electronic Science and Technology of China, Space Electronic Technology, Vol. 21, No. 4, pp. 2 - 3, August 2024, reported a millimeter wave down-conversion link system for a vector network analyzer spread spectrum system. This paper proposed a link architecture for a 50 GHz - 110 GHz broadband vector signal frequency conversion system, and described in the paper that "the down-conversion process of the 50 GHz - 110 GHz broadband signal is divided into two segments, namely 50 GHz - 75 GHz and 75 GHz - 110 GHz... For the down-conversion of segmented radio frequency signals, high and low local oscillators are respectively set. The harmonic components of non-desired signals can be found through two tests. That is, when the intermediate frequency signals are the same, different odd harmonic signals are identified, and then removed with the help of backend algorithms, which can effectively improve the spurious problem introduced by the nonlinearity of the mixer."

[0004] However, in order to suppress image frequency interference, the down-conversion architecture proposed in this paper uses a single-pole double-throw switch to divide the down-conversion system into two paths to implement a time-division frequency conversion system, resulting in a relatively large number of components required for the overall system. At the same time, in order to suppress the spurs generated by the mixer, through two measurements of high and low local oscillators and removing the spurs through software algorithms in the backend system, the problems are that the number of components used is relatively large, and the down-conversion system is complicated, which is not conducive to miniaturization and cost control. Summary of the Invention

[0005] The purpose of this application is to provide a simplified image rejection down-conversion millimeter-wave link system and its spurious suppression method, so as to at least solve the technical problems that suppressing spurious requires complex algorithms, a large number of devices are used, the system is relatively complex, and it is not conducive to miniaturization and cost control. The optional technical solutions among the many technical solutions provided by the present invention can produce many technical effects, which will be elaborated below.

[0006] To achieve the above object, in a first aspect, this application provides a simplified image rejection down-conversion millimeter-wave link system, including a millimeter-wave amplification module, a frequency multiplication amplification module, a down-conversion mixer, and a microwave intermediate-frequency amplification module. The output end of the millimeter-wave amplification module and the output end of the frequency multiplication amplification module are both connected to the input end of the down-conversion mixer, and the output end of the down-conversion mixer is connected to the input end of the microwave intermediate-frequency amplification module:

[0007] The millimeter-wave amplification module is used to receive a radio frequency signal, perform signal modulation processing on the radio frequency signal, and after dividing the modulation signal into n sub-signals of different frequency bands, input the sub-signals into the down-conversion mixer;

[0008] The frequency multiplication amplification module is used to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal, perform frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and input the high-frequency local oscillator signal into the down-conversion mixer;

[0009] The down-conversion mixer is used to mix each sub-signal with the corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and output the plurality of mixed signals to the microwave intermediate-frequency amplification module;

[0010] The microwave intermediate-frequency amplification module is used to filter out the spurious signals of each mixed signal to obtain an intermediate-frequency signal, and output the intermediate-frequency signal after amplification.

[0011] In some embodiments, the millimeter-wave amplification module includes an adjustable attenuator, an image rejection filter bank, and a low-noise amplifier. The adjustable attenuator is used to adjust the amplitude of the radio frequency signal to obtain the modulation signal; the image rejection filter bank is used to divide the modulation signal into n sub-signals of different frequency bands and is used to suppress the image frequencies corresponding to the frequencies; the low-noise amplifier is used to suppress the noise of the sub-signal or the modulation signal.

[0012] In some embodiments, the image rejection filter bank includes a first single-pole multi-throw switch, a second single-pole multi-throw switch, and a plurality of band-pass filters;

[0013] The switch shaft of the first single-pole multi-throw switch is connected to the output end of the adjustable attenuator, each wiring port of the first single-pole multi-throw switch is respectively connected to the input end of one of the band-pass filters, the output end of one of the band-pass filters is respectively connected to one wiring port of the second single-pole multi-throw switch, and the switch shaft of the second single-pole multi-throw switch is connected to the input end of the low-noise amplifier;

[0014] Alternatively, the switch shaft of the first single-pole multi-throw switch is connected to the output end of the low-noise amplifier, each wiring port of the first single-pole multi-throw switch is respectively connected to the input end of one of the band-pass filters, the output end of one of the band-pass filters is connected to one wiring port of the second single-pole multi-throw switch, and the switch shaft of the second single-pole multi-throw switch is connected to the input end of the down-conversion mixer.

[0015] In some embodiments, the frequency multiplication and amplification module includes a drive amplifier, a frequency multiplication filter bank, a third single-pole multi-throw switch, and a fourth single-pole multi-throw switch. The frequency multiplication filter bank includes a plurality of frequency multipliers and a plurality of filters; the switch shaft of the third single-pole multi-throw switch is used to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal, each wiring port of the third single-pole multi-throw switch is respectively connected to one of the frequency multipliers and one of the filters, the output end of one of the filters is connected to one wiring port of the fourth single-pole multi-throw switch, the switch shaft of the fourth single-pole multi-throw switch is connected to the input end of the drive amplifier, and the output end of the drive amplifier is connected to the input end of the down-conversion mixer.

[0016] In some embodiments, the microwave intermediate frequency amplification module includes a low-pass filter and a power amplifier. The input end of the low-pass filter is connected to the output end of the down-conversion mixer, and the output end of the low-pass filter is connected to the input end of the power amplifier; the low-pass filter is used to filter out the spurious signals of the intermediate frequency signal and then output it to the power amplifier, and the power amplifier is used to amplify the intermediate frequency signal after filtering out the spurious signals and then output it.

[0017] In a second aspect, the present application provides a spurious suppression method for a simplified image frequency rejection down-conversion millimeter-wave link system, which is applied to the simplified image frequency rejection down-conversion millimeter-wave link system according to any one of the first aspects, and includes:

[0018] The millimeter-wave amplification module receives a radio frequency signal, performs signal modulation processing on the radio frequency signal, and divides the modulated signal into n sub-signals of different frequency bands, and then inputs them into the down-conversion mixer;

[0019] After the frequency multiplication and amplification module receives the low-frequency local oscillator signal corresponding to the frequency of the sub-signal, it performs frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and inputs the high-frequency local oscillator signal into the down-conversion mixer;

[0020] The down-conversion mixer mixes each sub-signal with the corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and outputs the plurality of mixed signals to the microwave intermediate frequency amplification module;

[0021] The microwave intermediate frequency amplification module filters out the spurious signals of the mixed signal to obtain an intermediate frequency signal, and outputs the intermediate frequency signal after amplification.

[0022] In some embodiments, the down-conversion mixer mixes one sub-signal with the corresponding high-frequency local oscillator signal to generate a mixed signal, and the mixed signal includes a sum-frequency output signal, a difference-frequency output signal, and a spurious signal. The formula of the sum-frequency output signal is as follows:

[0023] ;

[0024] The formula of the difference-frequency output signal is as follows:

[0025] or ;

[0026] wherein, represents the frequency of the sum-frequency output signal, represents the frequency of the difference-frequency output signal, represents the frequency of the sub-signal, represents the frequency of the high-frequency local oscillator signal;

[0027] The formula of the spurious signal is as follows:

[0028] ;

[0029] wherein, represents the spurious signal, and both n and m are positive integers; when n + m = 3, the spurious signal is a third-order spurious signal.

[0030] In some embodiments, the method further includes:

[0031] Determine the filtering frequency band range of the low-pass filter in the microwave intermediate frequency amplification module according to the frequency of the difference-frequency output signal.

[0032] In some embodiments, when the difference-frequency output signal satisfies is a positive number, it is a low local oscillator mode, then the frequency band of the sub-signal and the frequency band of the high-frequency local oscillator signal satisfy a first relationship, and the formula of the first relationship is as follows:

[0033] , ;

[0034] The frequency of the intermediate frequency signal satisfies a second relationship, and the formula of the second relationship is as follows:

[0035] ;

[0036] Wherein, represents the maximum frequency value of the first intermediate frequency signal, represents the maximum frequency value of the second intermediate frequency signal, represents the maximum frequency value of the nth intermediate frequency signal, represents the maximum frequency value of the nth sub-signal, represents the frequency value of the high-frequency local oscillator signal of the nth mixing signal.

[0037] In some embodiments, the difference frequency output signal satisfies When it is a positive number, it is a high local oscillator mode; then the frequency band of the sub-signal and the frequency band of the high-frequency local oscillator signal satisfy a third relationship, and the formula of the third relationship is as follows:

[0038] , ;

[0039] The frequency of the intermediate frequency signal satisfies a fourth relationship, and the formula of the fourth relationship is as follows:

[0040] ;

[0041] Wherein, represents the maximum frequency value of the first intermediate frequency signal, represents the maximum frequency value of the second intermediate frequency signal, represents the maximum frequency value of the nth intermediate frequency signal, represents the minimum frequency value of the nth sub-signal, represents the frequency value of the high-frequency local oscillator signal of the nth mixing signal.

[0042] Implementing one of the above technical solutions of the present application has the following advantages or beneficial effects:

[0043] The simplified image frequency rejection down-conversion millimeter-wave link system and spurious suppression method of the present application. The millimeter-wave amplification module modulates and processes the received radio frequency signal to avoid signal distortion caused by subsequent non-linear devices operating in the saturation region. The modulated signal is divided into n sub-signals of different frequency bands, which can suppress the image frequency corresponding to the frequency, and is input to the down-conversion mixer. The low-frequency local oscillator signal received by the frequency multiplication and amplification module corresponds to the sub-signal. After frequency change and signal purification processing, a high-frequency local oscillator signal with pure frequency is obtained and input to the down-conversion mixer. The down-conversion mixer mixes the sub-signal and the corresponding high-frequency local oscillator signal, and then filters out spurious signals through the microwave intermediate frequency amplification module to obtain an intermediate frequency signal, realizing the simplification of the image frequency rejection down-conversion millimeter-wave link system. The number of devices used is small, reducing the complexity and cost of the system, and being able to achieve spurious suppression at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings. In the drawings:

[0045] Figure 1 is a schematic structural diagram of the simplified image frequency rejection down-conversion millimeter-wave link system according to the embodiment of the present application;

[0046] Figure 2 is a circuit diagram of the image rejection filter bank according to the embodiment of the present application;

[0047] Figure 3 is a circuit diagram of the frequency multiplication and amplification module according to the embodiment of the present application;

[0048] Figure 4 is a circuit diagram of the 67 GHz - 110 GHz image frequency rejection down-conversion millimeter-wave link system according to the embodiment of the present application;

[0049] Figure 5 is a circuit block diagram of the prior art 50 GHz - 110 GHz wideband signal down-conversion technology;

[0050] Figure 6 is a schematic flow diagram of the spurious suppression method of the simplified image frequency rejection down-conversion millimeter-wave link system according to the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] In order to make the objectives, technical solutions, and advantages of this application clearer and more understandable, various exemplary embodiments to be described below will refer to the corresponding drawings, which form a part of the exemplary embodiments and describe various exemplary embodiments that may be used to implement this application. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, devices, etc. consistent with some aspects of the disclosure of this application as detailed in the appended claims. Other embodiments may also be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and essence of this application.

[0052] In the description of this application, it should be understood that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. The meaning of the term "plurality" is two or more. The terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a communication connection, a direct connection, an indirect connection through an intermediate medium, or it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] In order to illustrate the technical solutions described in this application, the following will be illustrated through specific embodiments, and only the parts related to the embodiments of this application are shown.

[0054] In the first aspect, as Figure 1 shown, this application provides a simplified image rejection down-conversion millimeter-wave link system, including a millimeter-wave amplification module 10, a frequency multiplication amplification module 20, a down-conversion mixer 30, and a microwave intermediate-frequency amplification module 40. The output end of the millimeter-wave amplification module 10 and the output end of the frequency multiplication amplification module 20 are both connected to the input end of the down-conversion mixer 30, and the output end of the down-conversion mixer 30 is connected to the input end of the microwave intermediate-frequency amplification module 40.

[0055] The millimeter-wave amplification module 10 is configured to receive a radio frequency signal, perform signal modulation processing on the radio frequency signal, and after dividing the modulated signal into n sub-signals of different frequency bands, input them into the down-conversion mixer 30.

[0056] The frequency multiplication amplification module 20 is configured to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal, perform frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and input the high-frequency local oscillator signal into the down-conversion mixer 30.

[0057] The down-conversion mixer 30 is used to mix each sub-signal with a corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and output the plurality of mixed signals to the microwave intermediate-frequency amplification module 40.

[0058] The microwave intermediate-frequency amplification module 40 is used to filter out the spurious signals of each mixed signal to obtain an intermediate-frequency signal, and output it after amplifying the intermediate-frequency signal.

[0059] In some embodiments, the millimeter-wave amplification module 10 includes a tunable attenuator 11, an image rejection filter bank 12, and a low-noise amplifier 13. The tunable attenuator 11 is used to adjust the amplitude of the radio frequency signal to obtain a modulated signal; the image rejection filter bank 12 is used to divide the modulated signal into n sub-signals of different frequency bands to suppress the image frequencies corresponding to the frequencies; the low-noise amplifier 13 is used to suppress the noise of the sub-signal or the modulated signal.

[0060] Specifically, the tunable attenuator 11 adjusts the amplitude of the radio frequency signal to avoid signal distortion caused by subsequent non-linear devices (such as the subsequent low-noise amplifier 13 and down-conversion mixer 30) operating in the saturation region.

[0061] The low-noise amplifier 13 is placed in front of the down-conversion mixer 30, which can improve the noise figure performance of the system.

[0062] The image rejection filter bank 12 can be located between the tunable attenuator 11 and the low-noise amplifier 13, or between the low-noise amplifier 13 and the down-conversion mixer 30.

[0063] When the image rejection filter bank 12 is located between the tunable attenuator 11 and the low-noise amplifier 13, the image rejection filter bank 12 divides the modulated signal output by the tunable attenuator 11 into n sub-signals and inputs them into the low-noise amplifier 13 to improve the noise figure performance; when the image rejection filter bank 12 is located between the low-noise amplifier 13 and the down-conversion mixer 30, the low-noise amplifier 13 improves the noise figure performance of the modulated signal and then inputs it into the image rejection filter bank 12 for signal division.

[0064] In some embodiments, as Figure 2 shown, the image rejection filter bank 12 includes a first single-pole multi-throw switch S1, a second single-pole multi-throw switch S2, and a plurality of band-pass filters; the band-pass filters are Figure 2 BPF-1 to BPF-n in

[0065] The switch shaft of the first single-pole multi-throw switch S1 is connected to the output end of the adjustable attenuator 11. Each wiring port of the first single-pole multi-throw switch S1 is respectively connected to the input end of a band-pass filter. The output end of a band-pass filter is respectively connected to a wiring port of the second single-pole multi-throw switch S2. The switch shaft of the second single-pole multi-throw switch S2 is connected to the input end of the low-noise amplifier 13;

[0066] Alternatively, the switch shaft of the first single-pole multi-throw switch S1 is connected to the output end of the low-noise amplifier 13. Each wiring port of the first single-pole multi-throw switch S1 is respectively connected to the input end of a band-pass filter. The output end of a band-pass filter is connected to a wiring port of the second single-pole multi-throw switch S2. The switch shaft of the second single-pole multi-throw switch S2 is connected to the input end of the down-conversion mixer 30.

[0067] Specifically, the image rejection filter bank 12 is composed of a single-pole multi-throw switch and a band-pass filter combination. As Figure 2 shown, the modulation signal input to the image rejection filter bank 12 can be divided into n paths to suppress the image frequencies corresponding to the frequencies.

[0068] As Figure 2 shown, when the image rejection filter bank 12 is located between the adjustable attenuator 11 and the low-noise amplifier 13, the switch shaft of the first single-pole multi-throw switch S1 is connected to the output end of the adjustable attenuator 11, and the switch shaft of the second single-pole multi-throw switch S2 is connected to the input end of the low-noise amplifier 13. Through the cooperation of the first single-pole multi-throw switch S1 and the second single-pole multi-throw switch S2, the modulation signal can be divided into n sub-signals by using the band-pass filters BPF-1~BPF-n and then input to the low-noise amplifier 13 for noise suppression. After improving the noise figure performance, it is input to the down-conversion mixer 30.

[0069] When the image rejection filter bank 12 is located between the low-noise amplifier 13 and the down-conversion mixer 30, the switch shaft of the first single-pole multi-throw switch S1 is connected to the output end of the low-noise amplifier 13, and the switch shaft of the second single-pole multi-throw switch S1 is connected to the input end of the down-conversion mixer 30. Through the cooperation of the first single-pole multi-throw switch S1 and the second single-pole multi-throw switch S2, the modulation signal with improved noise figure performance is divided into n sub-signals by using the band-pass filters BPF-1~BPF-n and then input to the down-conversion mixer 30.

[0070] In some embodiments, such as Figure 1 and Figure 3As shown, the frequency doubling and amplification module 20 includes a drive amplifier 22, a frequency doubling filter bank 21, a third single-pole multi-throw switch S3, and a fourth single-pole multi-throw switch S4. The frequency doubling filter bank 21 includes a connected frequency doubler and filters BPF-1 to BPF-n. The switch shaft of the third single-pole multi-throw switch S3 is used to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal. Each connection port of the third single-pole multi-throw switch S3 is respectively connected to a frequency doubler and a filter. For example, frequency doubler-1 is connected to filter BPF-1, and frequency doubler-2 is connected to filter BPF-2. The output end of one filter is connected to one connection port of the fourth single-pole multi-throw switch S4. The switch shaft of the fourth single-pole multi-throw switch S4 is connected to the input end of the drive amplifier 22, and the output end of the drive amplifier 22 is connected to the input end of the down-conversion mixer 30.

[0071] Specifically, the frequency doubling and amplification module 20 includes a frequency doubling filter bank 21 and a drive amplifier 22. The frequency doubling filter bank 21 includes multiple groups of connected frequency doublers and filters. One frequency doubler is connected to one filter for generating the high-frequency local oscillator signal required by the down-conversion mixer 30. The drive amplifier 22 is used to amplify the power of the frequency-doubled signal, such as amplifying it by N times, to reach the local oscillator drive power of the down-conversion mixer 30 and ensure the normal operation of the down-conversion mixer 30.

[0072] In some embodiments, the microwave intermediate frequency amplification module 40 includes a low-pass filter 41 and a power amplifier 42. The input end of the low-pass filter 41 is connected to the output end of the down-conversion mixer 30, and the output end of the low-pass filter 41 is connected to the input end of the power amplifier 42. The low-pass filter 41 is used to filter out the spurious signals of the intermediate frequency signal and then output it to the power amplifier 42. The power amplifier 42 is used to amplify the intermediate frequency signal after filtering out the spurious signals and then output it.

[0073] Specifically, the low-pass filter 41 in the microwave intermediate frequency amplification module 40 is used to filter out spurious signals, especially the third-order spurious signals that interfere with the intermediate frequency signal. Therefore, the filtering frequency band of the low-pass filter 41 corresponds to the frequency band of the third-order spurious signals. The power amplifier 42 is used to amplify the power of the intermediate frequency signal and then output it, realizing the output of the intermediate frequency signal of the image frequency rejection down-conversion millimeter wave link system, so as to be applied in the test instrument spread spectrum system and the millimeter wave broadband radar scanning system.

[0074] The simplified image rejection down-conversion millimeter-wave link system of the present application uses a millimeter-wave amplification module 10 to divide the radio frequency signal into n sub-signals to suppress image frequency interference, thereby implementing a time-division frequency conversion system. To suppress the spurious signals generated by the down-conversion mixer 30, through the conversion of the local oscillator signal from low frequency to high frequency of the down-conversion mixer 30 and the filtering of the spurious signals of the mixed signals by the microwave intermediate frequency amplification module 40, the image rejection down-conversion millimeter-wave link system is simplified. Compared with the problem of a large number of devices caused by measuring the local oscillator signal using a backend software algorithm and suppressing the spurious signals generated by the system, the present application can greatly reduce the number of devices, greatly reducing the complexity and cost of the system.

[0075] Based on the simplified image rejection down-conversion millimeter-wave link system, for an input radio frequency signal in the range of 67 GHz to 110 GHz, the radio frequency signal is down-converted to a lower intermediate frequency band, and the third-order spurious signals are excluded from the intermediate frequency band. The highest intermediate frequency under each frequency band division is unified. A 67 GHz to 110 GHz image rejection down-conversion millimeter-wave link system is designed. The circuit diagram is as Figure 4As shown, the radio frequency signal of 67 GHz to 110 GHz is input through Port 1. The radio frequency signal is input to the variable attenuator VVA to adjust the amplitude to obtain a modulated signal. The image rejection filter bank uses two single-pole double-throw switches and two band-pass filters (BPF-1 / BPF-2) to divide the modulated signal into two sub-signals with frequency bands of 67~90 GHz and 90~110 GHz respectively. After the noise suppression of the low-noise amplifier LNA, it is input to the down-conversion mixer MIXER. At the same time, according to the frequency bands of the two sub-signals, two corresponding low-frequency local oscillator signals, namely 15.5 GHz and 10.25 GHz, are set and input through Port 3. Among them, frequency band 1 (67~90 GHz) corresponds to low-frequency local oscillator signal 1 (15.5 GHz), and frequency band 2 (90~110 GHz) corresponds to low-frequency local oscillator signal 2 (10.25 GHz). In the frequency multiplier amplification module, the frequency multiplier MULT-1 amplifies the low-frequency local oscillator signal 1 by 4 times and filters it in the filter BPF-3 to obtain the high-frequency local oscillator signal 1 of 62 GHz. The frequency multiplier MULT-2 amplifies the low-frequency local oscillator signal 2 by 8 times and filters it in the filter BPF-4 to obtain the high-frequency local oscillator signal 2 of 82 GHz. Then, through the single-pole double-throw switch, the two high-frequency local oscillator signals are respectively input to the driver amplifier PA-2 for processing, and then input to the down-conversion mixer MIXER for mixing processing, realizing the mixing of frequency band 1 (67~90 GHz) with the high-frequency local oscillator signal 1 of 62 GHz and the mixing of frequency band 2 (90~110 GHz) with the high-frequency local oscillator signal 2 of 82 GHz. In the microwave intermediate frequency amplification module connected to the down-conversion mixer MIXER, the frequency band of the low-pass filter LPF can be set to DC~28 GHz, so that the third-order spurious signals of the two mixed signals can be filtered out. After the amplification processing of the power amplifier PA-1, the intermediate frequency signals of 5~28 GHz and 8~28 GHz are output from Port 2.

[0076] Compared with the current Figure 5 design architecture as shown, Figure 5 It is the schematic diagram of the relevant circuit structure of the journal paper "50 GHz~110 GHz Wideband Signal Down-Conversion Technology" and the block diagram of the 50GHz~110GHz wideband vector signal frequency conversion system. Obviously, the number of devices required for this system is 26. For the simplified 67GHz~110GHz image rejection down-conversion millimeter-wave link system of this application, only 16 devices are needed, and the number of devices is reduced by 38%, simplifying the system composition architecture, thus greatly reducing the complexity and cost of the system.

[0077] In the second aspect, the present application also provides a spurious suppression method for the simplified image rejection down-conversion millimeter-wave link system, which is applied to the simplified image rejection down-conversion millimeter-wave link system described in any item of the first aspect, as Figure 6As shown, the spurious signal suppression method of the simplified image frequency rejection down-conversion millimeter-wave link system may include steps S100 to S400.

[0078] S100. The millimeter-wave amplification module receives a radio frequency signal, performs signal modulation processing on the radio frequency signal, and divides the modulated signal into n sub-signals of different frequency bands, and then inputs them into the down-conversion mixer.

[0079] S200. After the frequency doubling and amplification module receives the low-frequency local oscillator signal corresponding to the frequency of the sub-signal, it performs frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and inputs the high-frequency local oscillator signal into the down-conversion mixer.

[0080] S300. The down-conversion mixer mixes each sub-signal with the corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and outputs the plurality of mixed signals to the microwave intermediate frequency amplification module.

[0081] S400. The microwave intermediate frequency amplification module filters out the spurious signals of the mixed signals to obtain an intermediate frequency signal, and outputs the intermediate frequency signal after amplification.

[0082] Specifically, the circuit structure of the simplified image frequency rejection down-conversion millimeter-wave link system has been described in detail above and will not be elaborated here.

[0083] The millimeter-wave amplification module divides the input radio frequency signal into n frequency bands, one frequency band is one sub-signal, which are f RF1min ~f RF1max , f RF2min ~f RF2max , …, f RFnmin ~f RFnmax . And the bandwidths of each frequency band are as equal as possible, that is, the difference between two frequency bands is within a certain range. Then, in the image rejection filter bank of the millimeter-wave amplification module, the filtering frequency band of the band-pass filter BPF-1 is f RF1min ~f RF1max , the filtering frequency band of the band-pass filter BPF-2 is f RF2min ~f RF2max , …, the filtering frequency band of the band-pass filter BPF-n is f RFnmin ~f RFnmax .

[0084] Then, set the frequency bands of the local oscillator signals according to the frequency band division, which are f LO1 (corresponding to the sub-signal frequency band of f RF1min ~f RF1max ), f LO2 (corresponding to the sub-signal frequency band of f RF2min ~f RF2max ), ……, f LOn(The corresponding sub-signal frequency band is f RFnmin ~f RFnmax ). Then, among the filter and the local oscillator signal frequency multiplication factor N in the frequency multiplication and amplification module, the filtering frequency point of the filter BPF-1 is f LO1 , the filtering frequency point of the filter BPF-2 is f LO2 , ……, the filtering frequency point of the filter BPF-n is f LOn .

[0085] Next, when the down-conversion mixer performs mixing, the frequency bands of the obtained intermediate-frequency signals are respectively f IF1min ~f IF1max , f IF2min ~f IF2max , ……, f IFnmin ~f IFnmax .

[0086] In some embodiments, the down-conversion mixer mixes one of the sub-signals with a corresponding high-frequency local oscillator signal to generate a mixed signal, and the mixed signal includes a sum-frequency output signal, a difference-frequency output signal, and a spurious signal. The formula of the sum-frequency output signal is as follows:

[0087] ;

[0088] The formula of the difference-frequency output signal is as follows:

[0089] Or ;

[0090] Wherein, represents the frequency of the sum-frequency output signal, represents the frequency of the difference-frequency output signal, represents the frequency of the sub-signal, represents the frequency of the high-frequency local oscillator signal;

[0091] The formula of the spurious signal is as follows:

[0092] ;

[0093] Wherein, represents the spurious signal, and n and m are both positive integers; when n + m = 3, the spurious signal is a third-order spurious signal.

[0094] In some embodiments, the method may further include:

[0095] Determine the filtering frequency band range of the low-pass filter in the microwave intermediate-frequency amplification module according to the frequency of the difference-frequency output signal.

[0096] Specifically, in the microwave intermediate frequency amplification module, the passband of the low-pass filter is set to DC~f IFmax .

[0097] In some embodiments, the difference frequency output signal satisfies When it is a positive number, it is the low local oscillator mode. In order to remove the third-order spurious signal that has the greatest impact on the system generated after mixing by the down-conversion mixer, the frequency band of the sub-signal and the frequency band of the high-frequency local oscillator signal satisfy the first relationship, and the formula of the first relationship is as follows:

[0098] , ;

[0099] The frequency of the intermediate frequency signal satisfies the second relationship, and the formula of the second relationship is as follows:

[0100] ;

[0101] Wherein, represents the maximum frequency value of the first intermediate frequency signal, represents the maximum frequency value of the second intermediate frequency signal, represents the maximum frequency value of the nth intermediate frequency signal, represents the maximum frequency value of the nth sub-signal, represents the frequency value of the high-frequency local oscillator signal of the nth mixed signal.

[0102] In some embodiments, the difference frequency output signal satisfies When it is a positive number, it is the high local oscillator mode; then the frequency band of the sub-signal and the frequency band of the high-frequency local oscillator signal satisfy the third relationship, and the formula of the third relationship is as follows:

[0103] , ;

[0104] The frequency of the intermediate frequency signal satisfies the fourth relationship, and the formula of the fourth relationship is as follows:

[0105] ;

[0106] Wherein, represents the maximum frequency value of the first intermediate frequency signal, represents the maximum frequency value of the second intermediate frequency signal, represents the maximum frequency value of the nth intermediate frequency signal, represents the minimum frequency value of the nth sub-signal, represents the frequency value of the high-frequency local oscillator signal of the nth mixed signal.

[0107] For the aforementioned 67 GHz - 110 GHz image rejection down - conversion millimeter - wave link system, with a 67 GHz - 110 GHz RF signal as the input, which is required to be down - converted to a lower - frequency intermediate frequency IF. In its spurious suppression method, to achieve third - order spurious signal suppression and simplify the link structure, the input RF signal is divided into two relatively equal - width broadband signals, and the limiting conditions in the spurious suppression method are satisfied. This frequency band is divided into Band 1 (67 GHz - 90 GHz) and Band 2 (90 GHz - 110 GHz). The process of these two sub - signals passing through the down - conversion mixer and mixing with the fed local oscillator signal LO is as follows:

[0108] For Band 1, with a frequency range of 67 GHz - 90 GHz, the high - frequency local oscillator signal f LO1 has a frequency range of 15.5×4 = 62 GHz, the intermediate - frequency signal f IF has a frequency of 5 - 28 GHz, and the image frequency is GHz, and the third - order spurious frequencies are = 34 - 57 GHz and = 72 - 118 GHz.

[0109] Specifically: After the down - conversion mixer mixes Band 1 and the high - frequency local oscillator signal f LO1 , the sum - frequency output signal is . Obviously, this sum - frequency output signal is an unwanted mixing product and can be filtered out by a low - pass filter later.

[0110] The difference - frequency output signal is . This difference - frequency output signal is the desired down - conversion mixing product, that is, the frequency band of the intermediate - frequency signal.

[0111] The third - order spurious signals are respectively:

[0112] Substitute f RF , f LO into , and the output spurious frequency is 72 - 118 GHz;

[0113] Substitute f RF , f LO into , and the output spurious frequency is 34 - 57 GHz;

[0114] Substitute f RF , f LO into , and the output spurious frequency is 196 - 242 GHz;

[0115] Substitute f RF , f LO into , and the output spurious frequency is 191 - 214 GHz.

[0116] The above third-order spurious signals can all be filtered out by a low-pass filter with a frequency range of 0 to 28 GHz, so as to achieve the purpose of removing the third-order spurious signals.

[0117] Band 2, with a frequency range of 90 GHz to 110 GHz, the high-frequency local oscillator signal f LO2 has a frequency range of 10.25 × 8 = 82 GHz, and the intermediate-frequency signal f IF has a frequency of 8 to 28 GHz, and the image frequency is GHz, and the third-order spurious frequency is = 54 to 74 GHz and = 98 to 138 GHz.

[0118] Specifically: After the down-conversion mixer mixes Band 2 and the high-frequency local oscillator signal f LO2 , the sum-frequency output signal is . Obviously, this sum-frequency output signal is an unwanted mixing product and can be filtered out by a low-pass filter later.

[0119] The difference-frequency output signal is . This difference-frequency output signal is the desired down-conversion mixing product, that is, the frequency band of the intermediate-frequency signal.

[0120] The third-order spurious signals are respectively:

[0121] Substitute f RF , f LO into , and the output spurious frequency is 98 to 138 GHz;

[0122] Substitute f RF , f LO into , and the output spurious frequency is 54 to 74 GHz;

[0123] Substitute f RF , f LO into , and the output spurious frequency is 262 to 302 GHz;

[0124] Substitute f RF , f LO into , and the output spurious frequency is 254 to 274 GHz.

[0125] The above third-order spurious signals can all be filtered out by the same 0 to 28 GHz low-pass filter in the microwave intermediate-frequency amplification module, so as to achieve the purpose of removing the third-order spurious signals.

[0126] The spurious suppression method of the simplified image rejection down-conversion millimeter-wave link system of the present application multiplexes the same low-pass filter in the microwave intermediate-frequency amplification module, and does not use the method of combining two measurements of high and low local oscillators with a complex software algorithm at the backend to suppress spurious signals in the line of sight, and realizes the suppression of third-order spurious signals at a relatively low cost.

[0127] The above are only the preferred embodiments of the present invention. Those skilled in the art will know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present invention.

Claims

1. A simplified image suppression down-conversion millimeter wave link system, characterized in that: It includes a millimeter wave amplification module, a frequency doubling amplification module, a down-conversion mixer and a microwave intermediate frequency amplification module. The output end of the millimeter wave amplification module and the output end of the frequency doubling amplification module are both connected to the input end of the down-conversion mixer, and the output end of the down-conversion mixer is connected to the input end of the microwave intermediate frequency amplification module: The millimeter wave amplification module is used to receive a radio frequency signal, perform signal modulation processing on the radio frequency signal, and divide the modulated signal into n sub-signals of different frequency bands, and then input them into the down-conversion mixer; The frequency multiplication and amplification module is used to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal, and perform frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and input the high-frequency local oscillator signal into the down-conversion mixer; The down-conversion mixer is used to mix each of the sub-signals with the corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and output the plurality of mixed signals to the microwave intermediate frequency amplification module; The microwave intermediate frequency amplification module is used to filter out the stray signal of each mixing signal to obtain an intermediate frequency signal, and to amplify the intermediate frequency signal and then output it.

2. The simplified image-suppressed down-conversion millimeter-wave link system according to claim 1, characterized in that: The millimeter wave amplification module includes an adjustable attenuator, an image suppression filter group and a low noise amplifier. The adjustable attenuator is used to adjust the amplitude of the radio frequency signal to obtain the modulated signal; the image suppression filter group is used to divide the modulated signal into n sub-signals of different frequency bands to suppress the image frequency of the corresponding frequency; the low noise amplifier is used to suppress noise of the sub-signals or the modulated signal.

3. The simplified image-suppressed down-conversion millimeter-wave link system according to claim 2, characterized in that: The image rejection filter bank includes a first single-pole multi-throw switch, a second single-pole multi-throw switch and a plurality of bandpass filters; The switch shaft of the first single-pole multi-throw switch is connected to the output end of the adjustable attenuator, each connection port of the first single-pole multi-throw switch is respectively connected to an input end of the band-pass filter, an output end of the band-pass filter is respectively connected to a connection port of the second single-pole multi-throw switch, and the switch shaft of the second single-pole multi-throw switch is connected to the input end of the low-noise amplifier; Alternatively, the switch shaft of the first single-pole multi-throw switch is connected to the output end of the low-noise amplifier, each wiring port of the first single-pole multi-throw switch is respectively connected to an input end of the band-pass filter, an output end of the band-pass filter is connected to a wiring port of the second single-pole multi-throw switch, and the switch shaft of the second single-pole multi-throw switch is connected to the input end of the down-conversion mixer.

4. The simplified image-suppressed down-conversion millimeter-wave link system according to claim 1, characterized in that: The frequency multiplication amplification module includes a driving amplifier, a frequency multiplication filter group, a third single-pole multi-throw switch and a fourth single-pole multi-throw switch, the frequency multiplication filter group includes multiple frequency multipliers and multiple filters; the switch shaft of the third single-pole multi-throw switch is used to receive a low-frequency local oscillator signal corresponding to the frequency of the sub-signal, each wiring port of the third single-pole multi-throw switch is respectively connected to a frequency multiplier and a filter, an output end of one of the filters is connected to a wiring port of the fourth single-pole multi-throw switch, the switch shaft of the fourth single-pole multi-throw switch is connected to the input end of the driving amplifier, and the output end of the driving amplifier is connected to the input end of the down-conversion mixer.

5. The simplified image-suppressed down-conversion millimeter-wave link system according to claim 1, characterized in that: The microwave intermediate frequency amplification module includes a low-pass filter and a power amplifier, the input end of the low-pass filter is connected to the output end of the down-conversion mixer, and the output end of the low-pass filter is connected to the input end of the power amplifier; the low-pass filter is used to filter out the spurious signal of the intermediate frequency signal and then output it to the power amplifier, and the power amplifier is used to amplify the intermediate frequency signal after filtering out the spurious signal and then output it.

6. A simplified spurious suppression method for an image frequency suppression down-conversion millimeter wave link system, applied to the simplified image frequency suppression down-conversion millimeter wave link system according to any one of claims 1 to 5, characterized in that: include: The millimeter wave amplification module receives the radio frequency signal, performs signal modulation processing on the radio frequency signal, and divides the modulated signal into n sub-signals of different frequency bands, and then inputs the sub-signals into the down-conversion mixer; After receiving the low-frequency local oscillator signal corresponding to the frequency of the sub-signal, the frequency multiplication and amplification module performs frequency change processing and signal purification processing on the low-frequency local oscillator signal to obtain a high-frequency local oscillator signal, and inputs the high-frequency local oscillator signal into the down-conversion mixer; The down-conversion mixer mixes each of the sub-signals with a corresponding high-frequency local oscillator signal to generate a plurality of mixed signals, and outputs the plurality of mixed signals to the microwave intermediate frequency amplification module; The microwave intermediate frequency amplification module filters out the stray signal of the mixing signal to obtain an intermediate frequency signal, amplifies the intermediate frequency signal and then outputs it.

7. The simplified spurious suppression method of the image frequency suppression down-conversion millimeter wave link system according to claim 6, characterized in that: The down-conversion mixer mixes one of the sub-signals with a corresponding high-frequency local oscillator signal to generate a mixed signal, wherein the mixed signal includes a sum frequency output signal, a difference frequency output signal and a spurious signal. The formula of the sum frequency output signal is as follows: ； The formula of the difference frequency output signal is as follows: or ; in, represents the frequency of the sum frequency output signal, represents the frequency of the difference frequency output signal, represents the frequency of the sub-signal, represents the frequency of the high-frequency local oscillator signal; The formula for the spurious signal is as follows: ； in, represents a spurious signal, n and m are both positive integers; when n+m=3, the spurious signal is a third-order spurious signal.

8. The simplified spurious suppression method of the image frequency suppression down-conversion millimeter wave link system according to claim 7, characterized in that: The method further comprises: The filtering frequency band range of the low-pass filter in the microwave intermediate frequency amplification module is determined according to the frequency of the difference frequency output signal.

9. The simplified spurious suppression method of the image frequency suppression down-conversion millimeter wave link system according to claim 7, characterized in that: The difference frequency output signal satisfies When is a positive number, it is a low local oscillation mode, then the frequency band of the sub-signal and the frequency band of the high-frequency local oscillation signal satisfy the first relationship, and the formula of the first relationship is as follows: ， ； The frequency of the intermediate frequency signal satisfies a second relationship, and the formula of the second relationship is as follows: ； in, Indicates the maximum frequency value of the first intermediate frequency signal. Indicates the maximum frequency value of the second intermediate frequency signal. Indicates the maximum frequency value of the nth intermediate frequency signal, represents the maximum frequency value of the nth sub-signal, Indicates the frequency value of the high-frequency local oscillator signal of the nth mixing signal.

10. The simplified spurious suppression method of the image frequency suppression down-conversion millimeter wave link system according to claim 7, characterized in that: The difference frequency output signal satisfies When is a positive number, it is a high local oscillation mode; then the frequency band of the sub-signal and the frequency band of the high-frequency local oscillation signal satisfy the third relationship, and the formula of the third relationship is as follows: ， ； The frequency of the intermediate frequency signal satisfies the fourth relationship, and the formula of the fourth relationship is as follows: ； in, Indicates the maximum frequency value of the first intermediate frequency signal. Indicates the maximum frequency value of the second intermediate frequency signal. Indicates the maximum frequency value of the nth intermediate frequency signal, represents the minimum frequency value of the nth sub-signal, Indicates the frequency value of the high-frequency local oscillator signal of the nth mixing signal.

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