Simplified image frequency suppression down-conversion millimeter wave link system and spurious suppression method thereof

Abstract

The invention discloses a simplified image frequency suppression down-conversion millimeter wave link system and a spurious suppression method. The system comprises a millimeter wave amplification module, a frequency multiplication amplification module, a down-conversion mixer and a microwave intermediate frequency amplification module, and the output end of the millimeter wave amplification module and the output end of the frequency multiplication amplification module are both connected with the input end of the down-conversion mixer. The output end of the down-conversion mixer is connected with the input end of the microwave intermediate frequency amplification module. According to the invention, simplification of the image frequency suppression down-conversion millimeter wave link system is realized, the number of adopted devices is relatively small, the complexity and cost of the system are reduced, and spurious suppression can be realized with relatively low cost.

Description

Technical Field

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

[0002] Millimeter waves refer to electromagnetic waves with frequencies between 30 GHz and 300 GHz. This band shows great potential in the high-speed transmission of communication data due to its rich spectrum resources and the carrier bandwidth of up to hundreds of megahertz that it can provide. The millimeter wave band has been widely studied and applied in many fields such as anti-collision radar, high-resolution imaging, and ultra-wideband communication. The millimeter wave broadband down-conversion link system can down-convert the millimeter wave high-frequency signal in a wide frequency band to the microwave low-frequency band, and use a more mature microwave low-frequency band back-end system to process the signal, thereby realizing the processing and analysis of the millimeter wave high-frequency band broadband signal. The millimeter wave broadband down-conversion link system has extremely important application value in the test instrument spread spectrum system and the millimeter wave broadband radar scanning system, which is related to the performance of the entire system.

[0003] At present, a journal paper "50 GHz ~ 110 GHz broadband signal down-conversion technology" has been published, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Shenzhen Institute of Advanced Studies, University of Electronic Science and Technology of China, Space Electronics Technology, Vol. 21, No. 4, pp. 2-3, August 2024, reporting a millimeter wave down-conversion link system for vector network analyzer spread spectrum system. The paper proposes a 50 GHz ~ 110 GHz broadband vector signal frequency conversion system link architecture, and the paper describes "dividing the down-conversion process of the 50 GHz ~ 110GHz broadband signal into two sections, 50 GHz ~ 75 GHz and 75 GHz ~ 110 GHz... For the down-conversion of the segmented RF signal, high and low local oscillators are set respectively. The harmonic components of the undesired signal can be found through two tests, that is, when the intermediate frequency signal is the same, different odd harmonic signals are identified, and then removed with the help of the back-end algorithm, which can effectively improve the spurious problem introduced by the nonlinearity of the mixer."

[0004] However, in order to suppress the interference of the mirror frequency, the down-conversion architecture proposed in the paper uses a single-pole double-throw switch to divide the down-conversion system into two paths to realize the time-division frequency conversion system, resulting in a large number of components required for the entire system. At the same time, in order to suppress the spurious generated by the mixer, the high and low local oscillators are measured twice, and the spurious is removed by the software algorithm in the back-end system. The problem is that the number of components used is 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 the present application is to provide a simplified image frequency suppression down-conversion millimeter wave link system and its spurious suppression method, so as to at least solve the above-mentioned technical problems that the spurious suppression requires a complex algorithm, a large number of components, a relatively complex system, and is not conducive to miniaturization and cost control. The many technical effects that can be produced by the optional technical solutions among the many technical solutions provided by the present invention are described in detail below.

[0006] To achieve the above objectives, in a first aspect, the present application provides a simplified image frequency suppression down-conversion millimeter wave link system, comprising a millimeter wave amplification module, a frequency doubling amplification module, a down-conversion mixer and a microwave intermediate frequency amplification module, wherein 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.

[0007] In some embodiments, the millimeter wave amplification module includes an adjustable attenuator, an image suppression filter group and a low noise amplifier, wherein 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.

[0008] 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 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.

[0009] In some embodiments, 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, and 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 one of the frequency multipliers and one of the filters, 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.

[0010] 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 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.

[0011] In a second aspect, the present application provides a simplified spurious suppression method for an image frequency suppression down-conversion millimeter wave link system, which is applied to the simplified image frequency suppression down-conversion millimeter wave link system described in any one of the first aspects, including: 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.

[0012] 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, wherein the mixed signal includes a sum frequency output signal, a difference frequency output signal, and a spurious signal, and 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.

[0013] In some embodiments, 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.

[0014] In some embodiments, 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 second relationship formula 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.

[0015] In some embodiments, 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.

[0016] Implementing one of the above technical solutions of this application has the following advantages or beneficial effects: The simplified image frequency suppression down-conversion millimeter wave link system and spurious suppression method of the present application are as follows: the millimeter wave amplification module modulates the received radio frequency signal to avoid signal distortion caused by subsequent nonlinear devices working in the saturation region, and divides the modulated signal into n sub-signals of different frequency bands, which can suppress the image frequency of the corresponding frequency and input it into the down-conversion mixer; the low-frequency local oscillator signal received by the frequency multiplication amplification module corresponds to the sub-signal, and after frequency change and signal purification processing, a high-frequency local oscillator signal with pure frequency is obtained and then input into the down-conversion mixer, the down-conversion mixer mixes the sub-signal and the corresponding high-frequency local oscillator signal, and then the spurious signal is filtered out by the microwave intermediate frequency amplification module to obtain the intermediate frequency signal, so as to realize the simplification of the image frequency suppression down-conversion millimeter wave link system, adopt a small number of devices, reduce the complexity and cost of the system, and realize spurious suppression at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 It is a structural schematic diagram of a simplified image frequency suppression down-conversion millimeter wave link system according to an embodiment of the present application; Figure 2 is a circuit diagram of an image rejection filter group according to an embodiment of the present application; Figure 3 is a circuit diagram of a frequency doubling amplifier module according to an embodiment of the present application; Figure 4 67 GHz to 110 GHz image frequency suppression down-conversion millimeter wave link system of an embodiment of the present application; Figure 5 It is a circuit block diagram of the existing 50 GHz to 110 GHz broadband signal down-conversion technology; Figure 6 It is a flow chart of a simplified spurious suppression method for an image frequency suppression down-conversion millimeter wave link system according to an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the various exemplary embodiments to be described below will refer to the corresponding drawings, which constitute a part of the exemplary embodiments, wherein various exemplary embodiments that may be used to implement the present application are described. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. It should be understood that they are only examples of processes, methods, and devices that are consistent with some aspects disclosed in the present application as detailed in the attached claims, and other embodiments may also be used, or the embodiments listed herein may be modified in structure and function without departing from the scope and essence of the present application.

[0019] In the description of the present application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "plurality" means two or more. The terms "connected" and "connected" should be understood in a broad sense. For example, it can 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, and can be the internal connection of 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 the specific circumstances.

[0020] In order to illustrate the technical solution described in the present application, a specific embodiment is provided below, and only the parts related to the embodiment of the present application are shown.

[0021] First, as Figure 1As shown, the present application provides a simplified image suppression down-conversion millimeter wave link system, including a millimeter wave amplifier module 10, a frequency doubling amplifier module 20, a down-conversion mixer 30 and a microwave intermediate frequency amplifier module 40, the output end of the millimeter wave amplifier module 10 and the output end of the frequency doubling amplifier 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 amplifier module 40.

[0022] The millimeter wave amplification module 10 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 the sub-signals into the down-conversion mixer 30 .

[0023] The frequency multiplication and amplification module 20 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 30.

[0024] 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 .

[0025] The microwave intermediate frequency amplification module 40 is used to filter out the spurious signal of each mixing signal to obtain the intermediate frequency signal, and to amplify the intermediate frequency signal and then output it.

[0026] In some embodiments, the millimeter wave amplification module 10 includes an adjustable attenuator 11, an image suppression filter group 12 and a low noise amplifier 13. The adjustable attenuator 11 is used to adjust the amplitude of the radio frequency signal to obtain a modulated signal; the image suppression filter group 12 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 13 is used to suppress noise on the sub-signals or the modulated signal.

[0027] Specifically, the adjustable attenuator 11 adjusts the amplitude of the radio frequency signal to avoid signal distortion caused by subsequent nonlinear devices (such as the subsequent low noise amplifier 13 and down-conversion mixer 30) operating in the saturation region.

[0028] The low noise amplifier 13 is placed before the down-conversion mixer 30 to improve the noise figure performance of the system.

[0029] The image rejection filter bank 12 may be located between the adjustable attenuator 11 and the low noise amplifier 13 , or between the low noise amplifier 13 and the down-conversion mixer 30 .

[0030] When the image suppression filter group 12 is located between the adjustable attenuator 11 and the low noise amplifier 13, the image suppression filter group 12 divides the modulated signal output by the adjustable attenuator 11 into n-path sub-signals and then inputs them into the low noise amplifier 13 to improve the noise coefficient performance; when the image suppression filter group 12 is located between the low noise amplifier 13 and the down-conversion mixer 30, the low noise amplifier 13 improves the noise coefficient performance of the modulated signal and then inputs it into the image suppression filter group 12 for signal division.

[0031] In some embodiments, such as Figure 2 As shown, the image suppression filter group 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~BPF-n in .

[0032] The switch shaft of the first single-pole multi-throw switch S1 is connected to the output end of the adjustable attenuator 11, each connection 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 connection port of the second single-pole multi-throw switch S2, 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; 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 connection port of the first single-pole multi-throw switch S1 is respectively connected to the input end of a bandpass filter, the output end of a bandpass filter is connected to a connection port of the second single-pole multi-throw switch S2, and the switch shaft of the second single-pole multi-throw switch S2 is connected to the input end of the down-conversion mixer 30.

[0033] Specifically, the image suppression filter bank 12 is composed of a single-pole multi-throw switch and a bandpass filter. Figure 2 As shown, the modulated signal input to the image suppression filter bank 12 can be divided into n paths to suppress the image frequencies of corresponding frequencies.

[0034] like Figure 2 As shown, when the image suppression filter group 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 modulated signal can be divided into n-path signals by using bandpass filters BPF-1~BPF-n, and then input into the low noise amplifier 13 for noise suppression. After improving the noise coefficient performance, it is input into the down-conversion mixer 30.

[0035] When the image suppression filter group 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 modulated signal with improved noise coefficient performance is divided into n-path signals by using bandpass filters BPF-1~BPF-n and input into the down-conversion mixer 30.

[0036] In some embodiments, such as Figure 1 and Figure 3 As shown, the frequency multiplication amplification module 20 includes a driving amplifier 22, a frequency multiplication filter group 21, a third single-pole multi-throw switch S3 and a fourth single-pole multi-throw switch S4. The frequency multiplication filter group 21 includes a connected frequency multiplier and filters BPF-1~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 wiring port of the third single-pole multi-throw switch S3 is respectively connected to a frequency multiplier and a filter, for example, the frequency multiplier-1 is connected to the filter BPF-1, and the frequency multiplier-2 is connected to the filter BPF-2. The output end of a filter is connected to a wiring 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 driving amplifier 22, and the output end of the driving amplifier 22 is connected to the input end of the down-conversion mixer 30.

[0037] Specifically, the frequency multiplication and amplification module 20 includes a frequency multiplication filter group 21 and a driving amplifier 22. The frequency multiplication filter group 21 includes multiple groups of connected frequency multipliers and filters, one frequency multiplier is connected to one filter, and is used to generate a high-frequency local oscillator signal required by the down-conversion mixer 30. The driving amplifier 22 is used to amplify the power of the frequency multiplied signal, such as amplifying it N times, to achieve the local oscillator driving power of the down-conversion mixer 30, so as to ensure the normal operation of the down-conversion mixer 30.

[0038] 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 stray signals of the intermediate frequency signal and then output it to the power amplifier 42, and the power amplifier 42 is used to amplify the intermediate frequency signal after the stray signals are filtered out and then output it.

[0039] Specifically, the low-pass filter 41 in the microwave intermediate frequency amplification module 40 is used to filter out spurious signals, especially 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 signal. The power amplifier 42 is used to amplify the power of the intermediate frequency signal and then output it to achieve the intermediate frequency signal output of the image frequency suppression 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.

[0040] The simplified image frequency suppression down-conversion millimeter wave link system of the present application adopts a millimeter wave amplification module 10 to suppress image frequency interference, and divides the radio frequency signal into n-path sub-signals, thereby realizing a time-division frequency conversion system; in order to suppress the spurious signal generated by the down-conversion mixer 30, the image frequency suppression down-conversion millimeter wave link system is simplified by converting the low frequency to high frequency local oscillator signal of the down-conversion mixer 30, and filtering the spurious signal of the mixing signal by the microwave intermediate frequency amplification module 40. Compared with the problem of a large number of components caused by using a back-end software algorithm to measure the local oscillator signal and suppress the spurious generated by the system, the present application can greatly reduce the number of components and greatly reduce the complexity and cost of the system.

[0041] Based on a simplified image frequency suppression down-conversion millimeter wave link system, for an input RF signal of 67GHz~110GHz, the RF signal is down-converted to a lower frequency intermediate frequency band, and the third-order spurious signal is excluded from the intermediate frequency band. The highest intermediate frequency under each frequency band is unified. A 67GHz~110GHz image frequency suppression down-conversion millimeter wave link system is designed. The circuit diagram is shown in Figure 4As shown, port 1 inputs a 67GHz~110GHz RF signal, and the RF signal is input into the adjustable attenuator VVA to adjust the amplitude to obtain a modulated signal. The image suppression filter group uses two single-pole double-throw switches and two bandpass filters (BPF-1 / BPF-2) to divide the modulated signal into two sub-signals with frequency bands of 67~90GHz and 90~110GHz respectively. After noise suppression by the low-noise amplifier LNA, the signal is input into 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 are set, which are 15.5 GHz and 10.25 GHz respectively, and are input from 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 multiplication and 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 a high frequency of 62 GHz. The low-frequency local oscillator signal 1 is received by the frequency multiplier MULT-2, which amplifies the low-frequency local oscillator signal 2 by 8 times, and is filtered in the filter BPF-4 to obtain the 82GHz high-frequency local oscillator signal 2. After passing through the single-pole double-throw switch, the two high-frequency local oscillator signals are respectively input into the driver amplifier PA-2 for processing, and then input into the down-conversion mixer MIXER for mixing processing, so that the frequency band 1 (67~90GHz) is mixed with the 62GHz high-frequency local oscillator signal 1, and the frequency band 2 (90~110GHz) is mixed with the 82GHz high-frequency local oscillator signal 2. 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~28GHz, so that the third-order spurious signals of the two mixing signals can be filtered out, and then the intermediate frequency signals are output from port 2 after amplification processing by the power amplifier PA-1, which are 5~28GHz and 8~28GHz respectively.

[0042] Compared with the current Figure 5 The design architecture shown, Figure 5 This is a schematic diagram of the relevant circuit structure of the journal article "50 GHz ~ 110 GHz broadband signal down-conversion technology", and a block diagram of the 50GHz ~ 110GHz broadband vector signal frequency conversion system. Obviously, the system requires 26 devices. The simplified 67GHz ~ 110GHz image frequency suppression down-conversion millimeter wave link system of this application only requires 16 devices, reducing the number of devices by 38%, simplifying the system composition architecture, and thus greatly reducing the complexity and cost of the system.

[0043] In a second aspect, the present application further provides a simplified spurious suppression method for an image frequency suppression down-conversion millimeter wave link system, which is applied to the simplified image frequency suppression down-conversion millimeter wave link system described in any one of the first aspects, such as Figure 6As shown, the simplified spurious suppression method of the image suppression down-conversion millimeter wave link system may include steps S100 to S400.

[0044] 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 the sub-signals into a down-conversion mixer.

[0045] S200, 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.

[0046] S300, 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 a microwave intermediate frequency amplification module.

[0047] S400, 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.

[0048] Specifically, the circuit structure of the simplified image frequency suppression down-conversion millimeter wave link system has been described in detail above and will not be repeated here.

[0049] The millimeter wave amplifier module divides the input RF signal into n frequency bands, each frequency band is a sub-signal, which are f RF1min ~f RF1max , f RF2min ~f RF2max , …, f RFnmin ~f RFnmax . In addition, the bandwidth of each frequency band is as equal as possible, that is, the difference between the two frequency bands is within a certain range. Then, in the image suppression filter group of the millimeter wave amplifier module, the filtering band of the bandpass filter BPF-1 is f RF1min ~f RF1max , the filtering frequency band of the bandpass filter BPF-2 is f RF2min ~f RF2max , ..., the filtering frequency band of the bandpass filter BPF-n is f RFnmin ~f RFnmax .

[0050] Then, the frequency bands of the local oscillator signal are set according to the frequency band division, which are f LO1 (The corresponding sub-signal frequency band is f RF1min ~f RF1max ), f LO2 (The corresponding sub-signal frequency band is f RF2min ~f RF2max ), ..., f LOn(The corresponding sub-signal frequency band is f RFnmin ~f RFnmax ). Then, among the filters in the frequency multiplication amplification module and the frequency multiplication multiple N of the local oscillator signal, the filtering frequency of the filter BPF-1 is f LO1 , the filtering frequency of filter BPF-2 is f LO2 , ..., the filtering frequency of the filter BPF-n is f LOn .

[0051] Then, when the down-conversion mixer is used for mixing, the frequency bands of the intermediate frequency signals obtained are f IF1min ~f IF1max 、f IF2min ~f IF2max ,……,f IFnmin ~f IFnmax .

[0052] In some implementations, 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, and 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.

[0053] In some embodiments, the method may further include: 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.

[0054] Specifically, in the microwave intermediate frequency amplifier module, the passband of the low-pass filter is set to DC~f IFmax .

[0055] In some embodiments, the difference frequency output signal satisfies When it is a positive number, it is a low local oscillator mode. In order to remove the third-order spurious signal that has the greatest impact on the system after the down-conversion mixer mixes, the frequency band of the sub-signal and the frequency band of the high-frequency local oscillator signal satisfy the first relationship. The formula of the first relationship is as follows: , ; The frequency of the intermediate frequency signal satisfies the second relationship, and the second relationship formula 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.

[0056] In some embodiments, the difference frequency output signal satisfies When it 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 third relationship formula is as follows: , ; The frequency of the intermediate frequency signal satisfies the fourth relationship, and the fourth relationship formula 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.

[0057] For the aforementioned 67GHz~110GHz image frequency suppression down-conversion millimeter wave link system, the 67GHz~110GHz RF signal is used as input and is required to be down-converted to a lower frequency band intermediate frequency IF. In its spurious suppression method, in order to achieve third-order spurious signal suppression and link structure simplification, the input RF signal is divided into two relatively equal broadband signals, and the restrictions in the spurious suppression method are met. The frequency band is divided into band 1 (67GHz~90GHz) and band 2 (90GHz~110GHz). 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: Band 1, frequency range is 67GHz~90GHz, high frequency local oscillator signal f LO1 The frequency band range is 15.5×4=62GHz, and the intermediate frequency signal f IF The frequency is 5~28GHz, and the mirror frequency is GHz, the third-order spurious frequency is =34~57GHz and =72~118GHz.

[0058] Specifically: the down-conversion mixer performs frequency band 1 and high-frequency local oscillator signal f LO1 After mixing, the sum frequency output signal is Obviously, the sum frequency output signal is an unwanted mixing product and can be subsequently filtered out by a low-pass filter.

[0059] The difference frequency output signal is The difference frequency output signal is the required down-conversion mixing product, that is, the frequency band of the intermediate frequency signal.

[0060] The third-order spurious signals are: f RF 、f LO Substitution , the output spurious frequency is 72~118GHz; f RF 、f LO Substitution , the output spurious frequency is 34~57GHz; f RF 、f LO Substitution , the output spurious frequency is 196~242GHz; f RF 、f LO Substitution , the output spurious frequency is 191~214GHz.

[0061] The above third-order spurious signals can all be filtered out by a 0~28GHz low-pass filter, thereby achieving the purpose of removing the third-order spurious signals.

[0062] Band 2, frequency range is 90GHz~110GHz, high frequency local oscillator signal f LO2 The frequency band range is 10.25×8=82GHz, and the intermediate frequency signal f IF The frequency is 8~28GHz, and the mirror frequency is GHz, the third-order spurious frequency is =54~74GHz and =98~138GHz.

[0063] Specifically: the down-conversion mixer is used for the frequency band 2 and the high-frequency local oscillator signal f LO2 After mixing, the sum frequency output signal is Obviously, the sum frequency output signal is an unwanted mixing product and can be subsequently filtered out by a low-pass filter.

[0064] The difference frequency output signal is The difference frequency output signal is the required down-conversion mixing product, that is, the frequency band of the intermediate frequency signal.

[0065] The third-order spurious signals are: f RF 、f LO Substitution , the output spurious frequency is 98~138GHz; f RF 、f LO Substitution , the output spurious frequency is 54~74GHz; f RF 、f LO Substitution , the output spurious frequency is 262~302GHz; f RF 、f LO Substitution , the output spurious frequency is 254~274GHz.

[0066] The above three-order spurious signals can all be filtered out by the same low-pass filter 0~28GHz in the microwave intermediate frequency amplification module, thereby achieving the purpose of removing the third-order spurious signals.

[0067] The simplified spurious suppression method of the image-frequency suppression down-conversion millimeter wave link system of the present application reuses the same low-pass filter in the microwave intermediate frequency amplification module, does not use two measurements of high and low local oscillators combined with a complex back-end software algorithm to suppress line-of-sight spuriousness, and achieves suppression of third-order spuriousness at a relatively low cost.

[0068] The above description is only the preferred embodiment of the present invention. It is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this 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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