Microstrip double-balanced orthogonal mixer

Abstract

The invention relates to a microstrip double-balanced quadrature mixer, which comprises a power divider, a first three-port balun, a second three-port balun, a first double-balanced mixer, a second double-balanced mixer, a first four-port balun, a second four-port balun and a 90-degree directional coupler, a local oscillator signal port, a radio frequency signal port, a first intermediate frequency signal port and a second intermediate frequency signal port are arranged; wherein the output ends of the two three-port Baluns and the output ends of the two four-port Baluns generate a pair of differential signals with the difference of 180 degrees; the 90-degree directional coupler generates two radio frequency signals with the difference of 90 degrees; two intermediate frequency signals are led out from the isolation ports of the two four-port Baluns. Therefore, a group of orthogonal radio frequency differential signals can be generated through the 90-degree directional coupler, and frequency mixing processing is performed through the double-balanced frequency mixer, so that the isolation degree of a radio frequency port and a local oscillation port is greatly improved, leakage of signals of the local oscillation port and signals of an intermediate frequency port is suppressed, and the image frequency rejection degree is improved.

Description

Technical Field

[0001] This application relates to the field of wireless communication technologies, and particularly to a microstrip double-balanced quadrature mixer. Background Art

[0002] With the development of modern wireless communication, radar detection, and electronic warfare and other fields, the performance requirements for radio frequency front-end signal processing circuits are becoming increasingly stringent. As one of the key components of the radio frequency front-end, the performance of the mixer directly affects the operating efficiency of the entire system.

[0003] In traditional mixer technologies, microstrip mixers are widely used because of their significant advantages such as small size, light weight, and easy integration. However, conventional microstrip mixers often face the severe challenge of insufficient isolation. The isolation between radio frequency signals, local oscillator signals, and intermediate frequency signals is poor, which easily causes mutual interference between signals. In addition, this signal interference will also cause the mixer to generate intermodulation distortion. These intermodulation products may fall within the useful signal frequency band, interfering with the normal signal output, resulting in the receiver being unable to correctly demodulate the signal and affecting the performance of the entire communication. However, in modern communication and radar systems, quadrature mixers are increasingly widely used. By mixing radio frequency signals with mutually orthogonal local oscillator signals or local oscillator signals with mutually orthogonal radio frequency signals, two orthogonal intermediate frequency output signals are generated, so that complete signal amplitude, frequency, and phase and other information can be obtained, improving the image rejection ratio while also enhancing the anti-interference ability of the communication system.

[0004] However, there are still many technical problems that have not been overcome in realizing high isolation in traditional quadrature mixers, and it is difficult to meet the urgent needs of current systems for high-isolation and high-performance quadrature mixing. Summary of the Invention

[0005] Based on this, it is necessary to provide a microstrip double-balanced quadrature mixer that can meet the requirements of current systems for high-isolation and high-performance quadrature mixing for the above technical problems.

[0006] In a first aspect, this application provides a microstrip double-balanced quadrature mixer, including: a power divider, a first three-port balun, a second three-port balun, a first double-balanced mixer, a second double-balanced mixer, a first four-port balun, a second four-port balun, and a 90° directional coupler, where:

[0007] The power divider is used to equally divide the input local oscillator signal to obtain a local oscillator signal LO1 and a local oscillator signal LO2;

[0008] The first three-port balun is used to equally divide and differentially process the local oscillator signal LO1 to obtain a differential local oscillator signal LO11 and a differential local oscillator signal LO12;

[0009] The second three-port balun is used to perform equal-power distribution and differential processing on the local oscillator signal LO2 to obtain a differential local oscillator signal LO21 and a differential local oscillator signal LO22;

[0010] The 90° directional coupler is used to perform equal-power distribution on an externally input radio frequency signal to obtain a radio frequency signal RF1 and a radio frequency signal RF2, and perform a 90° phase shift operation on the radio frequency signal RF2 to obtain a phase-shifted radio frequency signal RF2;

[0011] The first four-port balun is used to perform equal-power distribution and differential processing on the radio frequency signal RF1 to obtain a differential radio frequency signal RF11 and a differential radio frequency signal RF12;

[0012] The second four-port balun is used to perform equal-power distribution and differential processing on the phase-shifted radio frequency signal RF2 to obtain a differential radio frequency signal RF21 and a differential radio frequency signal RF22;

[0013] The first double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO11, the differential local oscillator signal LO12, the differential radio frequency signal RF11, and the differential radio frequency signal RF12;

[0014] The second double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO21, the differential local oscillator signal LO22, the differential radio frequency signal RF21, and the differential radio frequency signal RF22.

[0015] In one embodiment, the power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler all adopt a microstrip structure.

[0016] In one embodiment, the first three-port balun, the second three-port balun, the first four-port balun, and the second four-port balun all adopt a circular rat-race structure.

[0017] In one embodiment, a first intermediate frequency signal port is led out from the isolation port of the first four-port balun, and a second intermediate frequency signal port is led out from the isolation port of the second four-port balun;

[0018] The first intermediate frequency signal port is connected to the first double-balanced mixer, and the second intermediate frequency signal port is connected to the second double-balanced mixer;

[0019] Among them, the first intermediate frequency signal output from the first intermediate frequency signal port and the second intermediate frequency signal output from the second intermediate frequency signal port are orthogonal to each other.

[0020] In one embodiment, the first intermediate frequency signal port and the second intermediate frequency signal port are arranged on both sides of the connection line between the radio frequency signal port and the local oscillator signal port; the input port of the power divider is connected to the local oscillator signal port, and the input port of the 90° directional coupler is connected to the radio frequency signal port.

[0021] In one embodiment, the first double-balanced mixer and the second double-balanced mixer adopt a cross-type diode stack structure, and both the first double-balanced mixer and the second double-balanced mixer include four identical diodes connected end to end.

[0022] In one embodiment, the power divider adopts a Wilkinson power divider.

[0023] In one embodiment, the power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler are arranged on a substrate, and the substrate adopts a single-layer printed circuit board.

[0024] In one embodiment, the phase difference between the isolation port of the first four-port balun and the second four-port balun and their two output ports is 90 degrees.

[0025] In one embodiment, the first four-port balun and the second four-port balun adopt a mirror image structure.

[0026] For the above microstrip double-balanced quadrature mixer, by using a double-balanced mixer for mixing processing, the isolation degree between the radio frequency signal and the local oscillator signal can be effectively improved, and intermodulation distortion and signal leakage can be suppressed. By generating a pair of orthogonal radio frequency signals through a 90° directional coupler and mixing them with the radio frequency signal through two sets of double-balanced mixers respectively, a set of mutually orthogonal intermediate frequency output signals can be obtained, thereby improving the image frequency rejection ratio. In addition, in the preferred solution, the power divider, the first three-port balun, the second three-port balun, the first four-port balun, the second four-port balun, and the 90° directional coupler in the present application are all selected to be of microstrip structure, so that they are easy to be integrated with other microwave components such as filters and amplifiers on the same substrate, and are easy to process and manufacture, and can meet the requirements of mass production. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the accompanying drawings required for the description of the embodiments of the present application or related technologies. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic structural diagram of a microstrip double-balanced quadrature mixer in an embodiment;

[0029] Figure 2 It is a schematic layout structural diagram of a microstrip double-balanced quadrature mixer when applied to a local oscillator of 23.9 GHz / radio frequency of 24 GHz in an embodiment;

[0030] Figure 3 It is a schematic structural diagram of a three-port balun with a ring rat-race structure selected in an embodiment;

[0031] Figure 4 It is a schematic diagram of the simulation result of the isolation degree between the local oscillator signal port and the radio frequency signal port in an embodiment;

[0032] Figure 5 It is a schematic diagram of the simulation result of the isolation degree between two mutually orthogonal intermediate frequency signal ports in an embodiment;

[0033] Figure 6 It is a schematic diagram of the simulation result of the isolation degree between the radio frequency signal port and the intermediate frequency signal port, and between the local oscillator signal port and the intermediate frequency signal port in an embodiment. Specific embodiments

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the following further details the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] Exemplarily, as Figure 1 shown, a microstrip double-balanced quadrature mixer is provided, which may include: a power divider, a first three-port balun ( Figure 1 the three-port balun 1 in Figure 1 ), a second three-port balun ( Figure 1 the three-port balun 2 in Figure 1 ), a first double-balanced mixer ( Figure 1 the double-balanced mixer 1 in Figure 1The four-port balun 2) and 90° directional coupler therein. Among them, the power splitter is used to equally distribute the input local oscillator signal to obtain the local oscillator signal LO1 and the local oscillator signal LO2; the first three-port balun is used to equally distribute and differentially process the local oscillator signal LO1 to obtain the differential local oscillator signal LO11 and the differential local oscillator signal LO12; the second three-port balun is used to equally distribute and differentially process the local oscillator signal LO2 to obtain the differential local oscillator signal LO21 and the differential local oscillator signal LO22; the 90° directional coupler is used to equally distribute the externally input radio frequency signal to obtain the radio frequency signal RF1 and the radio frequency signal RF2, and perform a 90° phase shift operation on the radio frequency signal RF2 to obtain the phase-shifted radio frequency signal RF2; the first four-port balun is used to equally distribute and differentially process the radio frequency signal RF1 to obtain the differential radio frequency signal RF11 and the differential radio frequency signal RF12; the second four-port balun is used to equally distribute and differentially process the phase-shifted radio frequency signal RF2 to obtain the differential radio frequency signal RF21 and the differential radio frequency signal RF22; the first double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO11, the differential local oscillator signal LO12, the differential radio frequency signal RF11 and the differential radio frequency signal RF12; the second double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO21, the differential local oscillator signal LO22, the differential radio frequency signal RF21 and the differential radio frequency signal RF22.

[0036] Exemplarily, Figure 2 It is a schematic layout diagram of a microstrip double-balanced quadrature mixer applied to a local oscillator of 23.9 GHz / radio frequency of 24 GHz in an embodiment. In the figure, the black-filled lines are the traces on the surface layer of the single-layer printed circuit board, the white-filled lines are the traces on the bottom layer of the single-layer printed circuit board, the concentric circles are the vias from the surface layer to the bottom layer of the printed circuit board, and the black dotted boxes are the double-balanced mixers formed by connecting the heads and tails of 4 identical diodes. Combining Figure 2 with this, this mixer is provided with a local oscillator signal port A, a radio frequency signal port B, a first intermediate frequency signal port C1, a second intermediate frequency signal port C2, a power splitter 1, a first three-port balun 2, a second three-port balun 3, a 90° directional coupler 4, a first four-port balun 5, a second four-port balun 6, a first double-balanced mixer 7, and a second double-balanced mixer 8.

[0037] Among them, the local oscillator signal port is connected to a power divider, and the power divider is specifically a T-junction power divider. The output ends of the power divider are respectively connected to the first three-port balun and the second three-port balun, and the connection ends are respectively denoted as a and b. The first three-port balun and the second three-port balun are specifically loop rat-race couplers. The output ends of the first three-port balun are respectively connected to the positive electrode of diode D4 at c, the negative electrode of diode D3 at c, the negative electrode of diode D2 at d, and the positive electrode of diode D1 at d. The output ends of the second three-port balun are respectively connected to the positive electrode of diode D8 at e, the negative electrode of diode D7 at e, the negative electrode of diode D6 at f, and the positive electrode of diode D5 at f.

[0038] Among them, the intermediate frequency signal port C1 is led out from the isolation end n of the first four-port balun, and the intermediate frequency signal port C2 is led out from the isolation end o of the second four-port balun. The phase difference between the two output ports of each of the first three-port balun and the second three-port balun is 180°. The phase difference between the two output ports of each of the first four-port balun and the second four-port balun is 180°. The phase difference between the isolation end and the two output ports of each of the first four-port balun and the second four-port balun is 90°.

[0039] Exemplarily, Figure 3 is a schematic structural diagram of a three-port balun with a loop rat-race coupler structure selected in an embodiment; the first three-port balun, the second three-port balun, the first four-port balun, and the second four-port balun all adopt the loop rat-race coupler structure.

[0040] Combined with Figure 2 , the radio frequency signal port is connected to a 90° directional coupler at h. The 90° directional coupler 8 is specifically a branch-line hybrid network. The output ends of the 90° directional coupler are respectively connected to the first four-port balun and the second four-port balun at i and j. The first four-port balun and the second four-port balun 2 are specifically loop rat-race couplers. The output ends of the first four-port balun are respectively connected to the negative electrode of diode D4 at j, the positive electrode of diode D2 at port j, where part of the wiring is on the bottom layer of the printed circuit board, the positive electrode of diode D3 at port k, where part of the wiring is on the bottom layer of the printed circuit board, and the negative electrode of diode D1 at port k. The output ends of the second four-port balun are respectively connected to the negative electrode of diode D8 at the first port, the positive electrode of diode D6 at the first port, where part of the wiring is on the bottom layer of the printed circuit board, the positive electrode of diode D7 at port m, where part of the wiring is on the bottom layer of the printed circuit board, and the negative electrode of diode D5 at port m.

[0041] Exemplarily, the power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler all adopt a microstrip structure.

[0042] Exemplarily, the isolation port of the first four-port balun leads out a first intermediate frequency signal port, and the isolation port of the second four-port balun leads out a second intermediate frequency signal port; the first intermediate frequency signal port is connected to a first double-balanced mixer, and the second intermediate frequency signal port is connected to a second double-balanced mixer; wherein, the first intermediate frequency signal output from the first intermediate frequency signal port and the second intermediate frequency signal output from the second intermediate frequency signal port are orthogonal to each other.

[0043] Exemplarily, the first intermediate frequency signal port and the second intermediate frequency signal port are arranged on both sides of the connection line between the radio frequency signal port and the local oscillator signal port; the input port of the power divider is connected to the local oscillator signal port, and the input port of the 90° directional coupler is connected to the radio frequency signal port.

[0044] Exemplarily, the first double-balanced mixer and the second double-balanced mixer adopt a cross-type diode stack structure, and both the first double-balanced mixer and the second double-balanced mixer include four identical diodes connected end to end.

[0045] Exemplarily, the power divider adopts a Wilkinson power divider.

[0046] Exemplarily, the power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler are arranged on a substrate, and the substrate adopts a single-layer printed circuit board.

[0047] Exemplarily, the phase difference between the isolation port of the first four-port balun and its two output ports and the isolation port of the second four-port balun and its two output ports is 90 degrees.

[0048] [[ID=z18]]Exemplarily, the first four-port balun and the second four-port balun adopt a mirror image structure.

[0049] For the above-mentioned microstrip double-balanced quadrature mixer, by using a double-balanced mixer for mixing processing, the isolation degree between the radio frequency signal and the local oscillator signal can be effectively improved, and intermodulation distortion and signal leakage can be suppressed. By generating a pair of orthogonal radio frequency signals through a 90° directional coupler and mixing with the radio frequency signals through two groups of double-balanced mixers respectively, a group of mutually orthogonal intermediate frequency output signals can be obtained, thereby improving the image frequency rejection ratio. In addition, in the preferred solution, the power divider, the first three-port balun, the second three-port balun, the first four-port balun, the second four-port balun, and the 90° directional coupler in this application are all selected to be of microstrip structure, so that they are easy to be integrated with other microwave components such as filters and amplifiers on the same substrate, and are easy to process and manufacture, and can meet the requirements of mass production.

[0050] Optionally, the microstrip double-balanced quadrature mixer can be fabricated by printed circuit board manufacturing process. The circuit substrate selects ROGERS4350B with a thickness of 0.254 mm, the microstrip line impedance is 50 ohm, and the diode selects bat24-02LS.

[0051] Optionally, the center frequency of the local oscillator signal can be set to 23.9 GHz, denoted as f L0 , corresponding to a wavelength of λ LO ; the center frequency of the radio frequency signal can be 24 GHz, denoted as f RF ; the center frequency of the intermediate frequency signal is 100 MHz, denoted as f IF .

[0052] In this embodiment, the local oscillator signal is fed into the power divider from the local oscillator signal port. Since the power divider adopts an equal-power distribution T-junction design, the local oscillator signals at the output ports a and b are of the same amplitude and in phase. The local oscillator signals enter the first three-port balun and the second three-port balun from ports a and b respectively. Among them, the three-port balun structure is designed as Figure 3 shown. The first three-port balun and the second three-port balun adopt a mirror structure design. The length difference between the signal input end and the two signal output ends is λ LO / 2, corresponding to a phase difference of 180°. The first three-port balun and the second three-port balun respectively output a pair of local oscillator signals with the same amplitude and opposite directions. The local oscillator signal output by the first three-port balun enters the first double-balanced mixer composed of diodes D1, D2, D3, and D4 connected end to end. The local oscillator signal output by the second three-port balun enters the second double-balanced mixer composed of diodes D5, D6, D7, and D8 connected end to end.

[0053] In this embodiment, the radio frequency signal is fed into the 90° directional coupler from the radio frequency signal port. The 90° directional coupler adopts a branch-line hybrid network structure, and the radio frequency signal powers at the output ports h and i are equal, and there is a 90° phase shift between the output ports h and i. The radio frequency signal enters the first four-port balun and the second four-port balun from the ports h and i respectively. There is a 180° phase difference between the two output ends of the four-port balun, and an isolation end is led out between the two output ends. The isolation degree and the phase difference between the two output ends are both 90°. The output ends of the first four-port balun and the second four-port balun respectively output a pair of radio frequency signals with the same amplitude and opposite directions. The phase difference between the output end k of the first four-port balun and the signal at the output end of the second four-port balun is 90°. The phase difference between the output end j of the first four-port balun and the signal at the output end m of the second four-port balun is 90°. The phase difference between the isolation end n of the first four-port balun and the isolation end o of the second four-port balun is 90°. The radio frequency signal output by the first four-port balun enters the first double-balanced mixer composed of diodes D1, D2, D3, and D4 connected end to end. The mixed-frequency signal output by the second four-port balun enters the second double-balanced mixer composed of diodes D5, D6, D7, and D8 connected end to end.

[0054] In this embodiment, the local oscillator differential signal output by the first three-port balun and the differential signal output by the first four-port balun are mixed in the first double-balanced mixer to obtain the combined frequency components of the local oscillator and the radio frequency, f RF ±f LO . The mixed-frequency signal is led out from the first double-balanced mixer through the ports j and k to the isolation port n of the first four-port balun, and the port n is connected to the intermediate frequency signal port C1 of the whole board for output. Among them, part of the wiring is on the bottom layer of the printed circuit board. After output, an external low-pass filter can be used to obtain the difference frequency signal, and the center frequency is f RF -f LO , that is, the intermediate frequency signal. The local oscillator differential signal output by the second three-port balun and the differential signal output by the second four-port balun are mixed in the second double-balanced mixer to obtain the combined frequency components of the local oscillator and the radio frequency f RF ±f LO . The mixed-frequency signal is led out from the second double-balanced mixer through the first port and the port m to the isolation port o of the second four-port balun. The port is connected to the intermediate frequency signal port C₂ of the whole board for output. Among them, part of the wiring is on the bottom layer of the printed circuit board. After output, an external low-pass filter can be used to obtain the difference frequency component f RF -f LO , that is, the intermediate frequency signal.

[0055] In this embodiment, four diodes are selected and connected end to end to form a double-balanced mixer, and a cross-type tube stack structure is adopted, so that the radio frequency differential signal and the local oscillator differential signal are respectively applied to two pairs of diagonal diodes of the diode cross-type tube stack, as Figure 1As shown. During the conduction and cutoff of the diode, the radio frequency signal is transmitted through the conducting diode path. Due to the non-linear characteristics of the diode, when radio frequency signals and local oscillator signals with different frequencies pass through the diode, sum frequencies, difference frequencies, and other harmonic components will be generated, that is: mf RF ±nf LO . The combined frequency signal is led out from the isolation terminal of the four-port balun. Since the frequency of the difference frequency signal f RF -f LO is much lower than the frequencies of the sum frequency signal and other harmonic signals, therefore, after the mixer is externally connected with a low-pass filter, the difference frequency signal, that is, the intermediate frequency signal f IF .

[0056] In this embodiment, two sets of radio frequency differential signals are mixed with two sets of local oscillator differential signals. The local oscillator signals at the input ends of the first three-port balun and the second three-port balun are of the same amplitude and in the same phase. Since the first three-port balun and the second three-port balun adopt a mirror image design, the local oscillator signals at the output ends c and f are of the same amplitude and in the same phase, and the local oscillator signals at the output ends d and e are of the same amplitude and in the same phase. Therefore, the differential local oscillator signals output by the first three-port balun and the second three-port balun are of the same amplitude and in the same phase; the radio frequency signals at the input ends of the first four-port balun and the second four-port balun have the same amplitude and a phase difference of 90°. Since the first four-port balun and the second four-port balun adopt a mirror image design, the radio frequency signals at the output ends j and m have the same amplitude and a phase difference of 90°, and the radio frequency signals at the output ends k and m have the same amplitude and a phase difference of 90°. Therefore, the differential radio frequency signals output by the first four-port balun and the second four-port balun are of the same amplitude and orthogonal. The differential local oscillator signals entering the first double-balanced mixer and the second double-balanced mixer are of the same amplitude and in the same phase, and the differential radio frequency signals are of the same amplitude and orthogonal. The 90° phase difference of the radio frequency signal will be inherited by the intermediate frequency signal after mixing, that is, a pair of orthogonal intermediate frequency signals are generated after mixing.

[0057] In summary, the mixer in this embodiment can achieve the following functions: the local oscillator signal forms two sets of differential local oscillator signals with the same amplitude and opposite phases through the power divider, the first three-port balun, and the second three-port balun, and the radio frequency signal forms two sets of differential radio frequency signals with the same amplitude and orthogonal through the 90° directional coupler, the first four-port balun, and the second four-port balun. The two sets of differential signals pass through the mixer respectively, and finally a set of orthogonal intermediate frequency signals are output.

[0058] Exemplarily, Figure 4 is a schematic diagram of the simulation results of the isolation degree between the local oscillator signal port and the radio frequency signal port in an embodiment; Figure 4 shows the simulation results of the isolation degree between the local oscillator signal port and the radio frequency signal port when the local oscillator frequency is 23.9 GHz, the power is 15 dBm, the power of the radio frequency signal is -10 dBm, and the radio frequency signal frequency changes from 20 GHz to 30 GHz. From Figure 4It can be seen that when the radio frequency signal is in the frequency range of 23 to 25 GHz, the isolation between the radio frequency signal port and the local oscillator signal port is better than -60 dB, and when the radio frequency signal is in the frequency range of 21 to 29 GHz, the isolation between the radio frequency signal port and the local oscillator signal port is better than -50 dB.

[0059] Exemplarily, Figure 5 is a schematic diagram of the isolation simulation results of two mutually orthogonal intermediate frequency signal ports in an embodiment; Figure 5 shows the isolation simulation results of two mutually orthogonal intermediate frequency signal ports when the local oscillator frequency is 23.9 GHz, the power is 15 dBm, the radio frequency signal power is -10 dBm, and the radio frequency signal frequency changes from 20 GHz to 30 GHz. From Figure 5 it can be seen that when the radio frequency signal is in the frequency range of 22 to 26 GHz, the isolation between the first intermediate frequency signal port and the second intermediate frequency signal port is better than -48 dB, and when the radio frequency signal is in the frequency range of 21 to 27 GHz, the isolation between the first intermediate frequency signal port and the second intermediate frequency signal port is better than -35 dB.

[0060] Exemplarily, Figure 6 is a schematic diagram of the isolation simulation results of the radio frequency signal port and the intermediate frequency signal port, and the local oscillator signal port and the intermediate frequency signal port in an embodiment. Figure 6 shows the isolation simulation results of the radio frequency signal port and the intermediate frequency signal port, and the local oscillator signal port and the intermediate frequency signal port when the local oscillator frequency is 23.9 GHz, the power is 15 dBm, the radio frequency signal power is -10 dBm, and the radio frequency signal frequency changes from 20 GHz to 30 GHz. From Figure 6 it can be seen that when the radio frequency signal is in the frequency range of 22.5 to 25 GHz, the isolation between the local oscillator signal port and the intermediate frequency signal port is better than -30 dB, and when the radio frequency signal is in the frequency range of 21 to 29 GHz, the isolation between the radio frequency signal port and the intermediate frequency signal port is better than -24 dB.

[0061] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this application.

[0062] The above embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of this application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application should be subject to the appended claims.

Claims

1. A microstrip double-balanced quadrature mixer, characterized in that Including: Power divider, first three-port balun, second three-port balun, first double-balanced mixer, second double-balanced mixer, first four-port balun, second four-port balun, 90° directional coupler, where: The power divider is used to equally distribute the input local oscillator signal to obtain local oscillator signal LO1 and local oscillator signal LO2; The first three-port balun is used to equally distribute and differentially process the local oscillator signal LO1 to obtain differential local oscillator signal LO11 and differential local oscillator signal LO12; The second three-port balun is used to equally distribute and differentially process the local oscillator signal LO2 to obtain differential local oscillator signal LO21 and differential local oscillator signal LO22; The 90° directional coupler is used to equally distribute the externally input radio frequency signal to obtain radio frequency signal RF1 and radio frequency signal RF2, and perform a 90° phase shift operation on the radio frequency signal RF2 to obtain the phase-shifted radio frequency signal RF2; The first four-port balun is used to equally distribute and differentially process the radio frequency signal RF1 to obtain differential radio frequency signal RF11 and differential radio frequency signal RF12; The second four-port balun is used to equally distribute and differentially process the phase-shifted radio frequency signal RF2 to obtain differential radio frequency signal RF21 and differential radio frequency signal RF22; The first double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO11, the differential local oscillator signal LO12, the differential radio frequency signal RF11, and the differential radio frequency signal RF12; The second double-balanced mixer is used to perform mixing processing on the differential local oscillator signal LO21, the differential local oscillator signal LO22, the differential radio frequency signal RF21, and the differential radio frequency signal RF22.

2. The microstrip double-balanced quadrature mixer according to claim 1, wherein The power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler all adopt a microstrip structure.

3. The microstrip double-balanced quadrature mixer according to claim 1, wherein The first three-port balun, the second three-port balun, the first four-port balun, and the second four-port balun all adopt a circular squirrel-cage structure.

4. The microstrip double-balanced quadrature mixer according to claim 1, wherein The isolation port of the first four-port balun leads out a first intermediate frequency signal port, and the isolation port of the second four-port balun leads out a second intermediate frequency signal port; The first intermediate frequency signal port is connected to the first double-balanced mixer, and the second intermediate frequency signal port is connected to the second double-balanced mixer; Wherein, the first intermediate frequency signal output from the first intermediate frequency signal port and the second intermediate frequency signal output from the second intermediate frequency signal port are orthogonal to each other.

5. The microstrip double-balanced quadrature mixer according to claim 1, wherein The first intermediate frequency signal port and the second intermediate frequency signal port are arranged on both sides of the connection line between the radio frequency signal port and the local oscillator signal port; the input port of the power divider is connected to the local oscillator signal port, and the input port of the 90° directional coupler is connected to the radio frequency signal port.

6. The microstrip double-balanced quadrature mixer according to any one of claims 1 to 5, characterized in that, The first double-balanced mixer and the second double-balanced mixer adopt a cross-type diode stack structure, and both the first double-balanced mixer and the second double-balanced mixer include four identical diodes connected end to end.

7. The microstrip double-balanced quadrature mixer according to any one of claims 1 to 5, characterized in that The power divider adopts a Wilkinson power divider.

8. The microstrip double-balanced quadrature mixer according to any one of claims 1 to 5, characterized in that The power divider, the first three-port balun, the second three-port balun, the first double-balanced mixer, the second double-balanced mixer, the first four-port balun, the second four-port balun, and the 90° directional coupler are disposed on a substrate, and the substrate adopts a single-layer printed circuit board.

9. The microstrip double-balanced quadrature mixer according to any one of claims 1 to 5, characterized in that The phase difference between the isolation ports of the first four-port balun and the second four-port balun and their two output ports is 90 degrees.

10. The microstrip double-balanced quadrature mixer according to any one of claims 1 to 5, characterized in that, The first four-port balun and the second four-port balun adopt a mirror image structure.

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