Mixer

Abstract

The invention provides a frequency mixer. The frequency mixer comprises a double-balanced Gilbert frequency mixer, an interstage first coupling transformer, a variable gain buffer, an interstage second coupling transformer, an I / Q orthogonal passive frequency mixer and a TIA filter, the double-balance Gilbert mixer, the interstage first coupling transformer, the variable gain buffer, the interstage second coupling transformer, the I / Q orthogonal passive mixer and the TIA filter are electrically connected in sequence; the double-balanced Gilbert mixer is used for receiving the differential signal and mixing the differential signal with a local oscillator signal of the double-balanced Gilbert mixer to realize first down-conversion and output a difference frequency signal; the variable gain buffer is used for realizing amplification processing of different gains; the I / Q orthogonal passive mixer is used for mixing the I-path signal and the Q-path signal with a local oscillator signal to realize second down-conversion and output a difference frequency signal; the TIA filter is used for filtering an input difference frequency signal and then outputting an intermediate frequency signal. The mixer can realize adjustable gain, and has good linearity and noise performance.

Description

Technical Field

[0001] The present invention relates to the field of navigation technology, and in particular to a mixer. Background Art

[0002] In the design of mixers, linearity and gain are both very important indicators of mixers. In the receiving link, if the down-mixer at the front stage of the link has a higher gain, it can improve the gain of the entire link on the one hand, and improve the noise performance of the entire link on the other hand. Active mixers can provide good gain characteristics, but the linearity will be limited by the voltage margin and will be compressed due to the switch tube entering the deep triode region too early. The gain change of traditional mixers is achieved by changing the size of MOS tubes or changing the transconductance unit, resulting in a decrease in linearity and noise performance. How to provide a mixer with variable gain, good linearity and noise performance is a problem that needs to be solved urgently. Summary of the invention

[0003] The present invention provides a mixer, aiming to solve the problem in the prior art that the gain, linearity and noise performance of the mixer cannot be taken into account at the same time.

[0004] The embodiment of the present invention provides a mixer, comprising: a double-balanced Gilbert mixer, a first interstage coupling transformer, a variable gain buffer, a second interstage coupling transformer, an I / Q orthogonal passive mixer and a TIA filter;

[0005] The double-balanced Gilbert mixer, the first inter-stage coupling transformer, the variable gain buffer, the second inter-stage coupling transformer, the I / Q orthogonal passive mixer and the TIA filter are electrically connected in sequence;

[0006] The double-balanced Gilbert mixer is used to receive a differential signal and mix it with the local oscillator signal of the double-balanced Gilbert mixer to achieve the first down-conversion and output a difference frequency signal; the first interstage coupling transformer is used for impedance matching between the double-balanced Gilbert mixer and the variable gain buffer; the variable gain buffer is used to achieve amplification processing with different gains; the second interstage coupling transformer is used for impedance matching between the variable gain buffer and the I / Q orthogonal passive mixer, so that the output signal is a differential signal; the I / Q orthogonal passive mixer is used to mix the I-channel and Q-channel signals with the orthogonal local oscillator signal respectively to achieve the second down-conversion and output the difference frequency signal; the TIA filter is used to filter the input difference frequency signal and then output an intermediate frequency signal.

[0007] Further, the double-balanced Gilbert mixer includes: MOS transistor M11, MOS transistor M12, MOS transistor M13, MOS transistor M14, fifth MOS transistor M15, MOS transistor M16, resistor R11, resistor R12, capacitor C11, and capacitor C12;

[0008] The gate of MOS transistor M11 is connected to an output terminal of the previous stage; the source of MOS transistor M11 is grounded; the drain of MOS transistor M11 is respectively connected to the sources of MOS transistor M13 and MOS transistor M14; the gate of MOS transistor M12 is connected to another output terminal of the previous stage; the source of MOS transistor M12 is grounded; the drain of MOS transistor M12 is respectively connected to the sources of MOS transistor M15 and MOS transistor M16;

[0009] The drains of MOS transistor M13 and MOS transistor M15 are both connected to an input terminal of the next stage, and the drains of MOS transistor M14 and MOS transistor M16 are both connected to another input terminal of the next stage;

[0010] The gates of MOS transistor M13 and MOS transistor M16 are connected to each other, and are connected to the reference voltage through resistor R11 and to one end of the local oscillator signal source through capacitor C11; the gates of MOS transistor M14 and MOS transistor M15 are connected to each other, and are connected to the reference voltage through resistor R12 and to the other end of the local oscillator signal source through capacitor C12.

[0011] Further, the variable gain buffer is composed of multiple identical buffers connected in parallel. Each buffer includes: source negative feedback MOS transistor M21, source negative feedback MOS transistor M22, MOS transistor M23, MOS transistor M24, MOS capacitor C21, and MOS capacitor C22; the sources of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected to each other and grounded; the gates of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected to each other and connected to the control signal to achieve variable gain; the drain of source negative feedback MOS transistor M21 is connected to the source of MOS transistor M23, and the drain of source negative feedback MOS transistor M22 is connected to the source of MOS transistor M24; the gate of MOS transistor M23 is connected to one end of MOS capacitor C21 and connected to an output terminal of the previous stage, and the gate of MOS transistor M24 is connected to one end of MOS capacitor C22 and connected to another output terminal of the previous stage; the drain of MOS transistor M23 is connected to the other end of MOS capacitor C22 and connected to an input terminal of the next stage, and the drain of MOS transistor M24 is connected to the other end of MOS capacitor C21 and connected to another input terminal of the next stage.

[0012] Further, the variable gain buffer is composed of 4 buffers connected in parallel.

[0013] Furthermore, both the I / Q quadrature passive mixer and the TIA filter adopt a two-way design.

[0014] Furthermore, the I / Q quadrature passive mixer adopts a two-way double-balanced design and is composed of two-way parallel connection; each mixer is the same and includes: MOS transistor M31, MOS transistor M32, MOS transistor M33, MOS transistor M34; the source of MOS transistor M31 and the source of MOS transistor M32 are connected and connected to an output end of the second inter-stage coupling transformer; the source of MOS transistor M33 and the source of MOS transistor M34 are connected and connected to the other output end of the second inter-stage coupling transformer; the drain of MOS transistor M31 and the drain of MOS transistor M33 are connected and connected to an input end of the next stage; the drain of MOS transistor M32 and the drain of MOS transistor M34 are connected and connected to the other input end of the next stage; the gate of MOS transistor M31 and the gate of MOS transistor M44 are connected and connected to one end of the local oscillator signal source, and the gate of MOS transistor M32 and the gate of MOS transistor M33 are connected and connected to the other end of the local oscillator signal source.

[0015] Furthermore, both TIA filters adopt a two-way double-balanced design; they are composed of two-way parallel connection; each filter is the same and includes: an operational amplifier, MOS transistors M41, M42, M43, M44, M45, M46, resistors R41, R42, R43, R44, R45, R46;

[0016] The source of MOS transistor M41 is respectively connected to one end of resistor R41 and an input end of the operational amplifier; the drain of MOS transistor M41 is respectively connected to the other end of resistor R41, one end of resistor R42, and the source of MOS transistor M42; the drain of MOS transistor M42 is respectively connected to the other end of resistor R42, one end of resistor R43, and the source of MOS transistor M43; the drain of MOS transistor M43 is respectively connected to the other end of resistor R43 and an output end of the operational amplifier;

[0017] The source of MOS transistor M44 is respectively connected to one end of resistor R44 and the other input end of the operational amplifier; the drain of MOS transistor M44 is respectively connected to the other end of resistor R44, one end of resistor R45, and the source of MOS transistor M45; the drain of MOS transistor M45 is respectively connected to the other end of resistor R45, one end of resistor R46, and the source of MOS transistor M46; the drain of MOS transistor M46 is respectively connected to the other end of resistor R46 and the other output end of the operational amplifier.

[0018] Furthermore, the differential signal is obtained by output of the radio frequency signal through a single-to-differential unit.

[0019] Further, the single-conversion differential unit includes: balun T51, resistor R51, and resistor R52; the input end of balun T51 is connected to the RF signal input end; one output end and the other output end of balun T51 are respectively connected to the reference voltage through resistor R51 and resistor R52.

[0020] An embodiment of the present invention further provides an electronic device for navigation, using the mixer described above.

[0021] The mixer provided by the present invention comprehensively considers various performance indicators. By cleverly setting multiple variable-gain buffers Buffer between the double-balanced Gilbert mixer and the I / Q quadrature passive mixer, the gain is effectively compensated. At the same time, the TIA filter in the circuit can effectively reduce the noise of the mixer, thus taking into account the linearity, gain, and noise of the mixer, enabling the comprehensive performance of the mixer to meet the design requirements. It can not only achieve gain adjustment, but also has good linearity and noise performance. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a circuit schematic diagram of a mixer provided by an embodiment of the present invention;

[0024] Figure 2 It is a circuit diagram of a mixer provided by an embodiment of the present invention;

[0025] Figure 3 It is a circuit diagram of a double-balanced Gilbert mixer;

[0026] Figure 4 It is a circuit diagram of a variable-gain buffer;

[0027] Figure 5 It is a circuit diagram of an I / Q quadrature passive mixer;

[0028] Figure 6 It is a circuit diagram of a single-channel TIA filter;

[0029] Figure 7 It is a circuit diagram of a single-conversion differential unit. Detailed Embodiments

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] As Figure 1 , Figure 2 shown, a mixer includes: a double-balanced Gilbert mixer 101, a first inter-stage coupling transformer 102, a variable-gain buffer 103, a second inter-stage coupling transformer 104, an I / Q quadrature passive mixer 105, and a TIA (trans-impedance amplifier) filter 106. The double-balanced Gilbert mixer, the first inter-stage coupling transformer, the variable-gain buffer, the second inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence. The double-balanced Gilbert mixer is configured to receive a differential signal and mix it with the local oscillator signal of the double-balanced Gilbert mixer to achieve the first down-conversion and output a difference frequency signal; the first inter-stage coupling transformer is used for matching between the double-balanced Gilbert mixer and the variable-gain buffer; the variable-gain buffer is configured to perform amplification processing with different gains; the second inter-stage coupling transformer is used for matching between the variable-gain buffer and the I / Q quadrature passive mixer, so that the output signal is a differential signal; the I / Q quadrature passive mixer is configured to mix the I-channel and Q-channel signals with the orthogonal local oscillator signals respectively to achieve the second down-conversion and output a difference frequency signal; the TIA filter is configured to filter the input difference frequency signal and then output an intermediate frequency signal. The first inter-stage coupling transformer and the second inter-stage coupling transformer are used to achieve impedance matching, ensuring the maximum power transmission of signals between different modules. At the same time, the coupling transformer structure enables the bias voltages not to affect each other, and has a natural DC-blocking property, so that additional DC-blocking capacitors do not need to be used, further reducing the loss of passive devices.

[0032] As Figure 3As shown, the double-balanced Gilbert mixer includes: MOS transistor M11, MOS transistor M12, MOS transistor M13, MOS transistor M14, MOS transistor M15, MOS transistor M16, resistor R11, resistor R12, capacitor C11, and capacitor C12; the gate of MOS transistor M11 is connected to an output terminal of the previous stage; the source of MOS transistor M11 is grounded; the drain of MOS transistor M11 is respectively connected to the sources of MOS transistor M13 and MOS transistor M14; the gate of MOS transistor M12 is connected to another output terminal of the previous stage; the source of MOS transistor M12 is grounded; the drain of MOS transistor M12 is respectively connected to the sources of MOS transistor M15 and MOS transistor M16; the drains of MOS transistor M13 and MOS transistor M15 are both connected to an input terminal of the next stage, and the drains of MOS transistor M14 and MOS transistor M16 are both connected to another input terminal of the next stage; the gates of MOS transistor M13 and MOS transistor M16 are connected together, and are connected to the reference voltage through resistor R11 and to one end LON of the local oscillator signal source through capacitor C11; the gates of MOS transistor M14 and MOS transistor M15 are connected together, and are connected to the reference voltage through resistor R12 and to the other end LOP of the local oscillator signal source through capacitor C12.

[0033] As Figure 4As shown, the variable gain buffer is composed of four buffers in parallel, and the structure of each buffer is the same. Each buffer includes: source negative feedback MOS transistors M21 and M22, MOS transistors M23 and M24, MOS capacitors C21 and C22; the sources of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected together and grounded; the gates of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected together and connected to a control signal to achieve variable gain; the drain of source negative feedback MOS transistor M21 is connected to the source of MOS transistor M23, and the drain of source negative feedback MOS transistor M22 is connected to the source of MOS transistor M24; the gate of MOS transistor M23 is connected to one end of MOS capacitor C21 and connected to an output end of the previous stage, and the gate of MOS transistor M24 is connected to one end of MOS capacitor C22 and connected to another output end of the previous stage; the drain of MOS transistor M23 is connected to the other end of MOS capacitor C22 and connected to an input end of the next stage, and the drain of MOS transistor M24 is connected to the other end of MOS capacitor C21 and connected to another input end of the next stage. When the gates of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are both grounded, the MOS is cut off and the buffer is in the off state. When the gates of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are both connected to the power supply, the MOS is turned on and the buffer is in the on state. The variable gain buffer is composed of four buffers in parallel. By separately controlling the control signals DGND1 to DGND4 of each path to be grounded or connected to the power supply, the four buffers can be enabled one by one, two by two, three by three, and four by four, so as to achieve different gains.

[0034] The I / Q quadrature passive mixer adopts a two-path design, namely the I path and the Q path. As Figure 5 shown, one of the above paths is used for illustration; the single-path quadrature passive mixer includes: MOS transistors M31, M32, M33, and M34; the sources of MOS transistor M31 and MOS transistor M32 are connected together and connected to an output end of the second inter-stage coupling transformer; the sources of MOS transistor M33 and MOS transistor M34 are connected together and connected to another output end of the second inter-stage coupling transformer; the drains of MOS transistor M31 and MOS transistor M33 are connected together and connected to an input end of the next stage; the drains of MOS transistor M32 and MOS transistor M34 are connected together and connected to another input end of the next stage; the gates of MOS transistor M31 and MOS transistor M34 are connected together and connected to one end of the local oscillator signal source LO1 of this stage, and the gates of MOS transistor M32 and MOS transistor M33 are connected together and connected to the other end of the local oscillator signal source LO2 of this stage.

[0035] The TIA filter also adopts an I / Q two-path design. As Figure 6As shown, it is described by taking the above single path as an example; the single-path TIA filter includes: an operational amplifier, MOS transistor M41, MOS transistor M42, MOS transistor M43, MOS transistor M44, MOS transistor M45, MOS transistor M46, resistor R41, resistor R42, resistor R43, resistor R44, resistor R45, resistor R46;

[0036] The source of MOS transistor M41 is respectively connected to one end of resistor R41 and one input terminal of the operational amplifier; the drain of MOS transistor M41 is respectively connected to the other end of resistor R41, one end of resistor R42, and the source of MOS transistor M42; the drain of MOS transistor M42 is respectively connected to the other end of resistor R42, one end of resistor R43, and the source of MOS transistor M43; the drain of MOS transistor M43 is respectively connected to the other end of resistor R43 and one output terminal of the operational amplifier;

[0037] The source of MOS transistor M44 is respectively connected to one end of resistor R44 and the other input terminal of the operational amplifier; the drain of MOS transistor M44 is respectively connected to the other end of resistor R44, one end of resistor R45, and the source of MOS transistor M45; the drain of MOS transistor M45 is respectively connected to the other end of resistor R45, one end of resistor R46, and the source of MOS transistor M46; the drain of MOS transistor M46 is respectively connected to the other end of resistor R46 and the other output terminal of the operational amplifier.

[0038] When the mixer is used for navigation, the received signal at the front end is a radio frequency signal, and the radio frequency signal needs to be converted into a differential signal. Therefore, a single-to-differential unit is also provided at the previous stage of the double-balanced Gilbert mixer 101, which is used to convert the radio frequency signal into a differential signal and output it to the double-balanced Gilbert mixer 101.

[0039] As Figure 7 shown, the single-to-differential unit includes: balun T51, resistor R51, resistor R52; the input terminal of balun T51 is connected to the radio frequency signal input terminal; one output terminal and the other output terminal of balun T51 are respectively connected to the reference voltage through resistor R51 and resistor R52. The balun is a broadband radio frequency transmission line transformer that realizes the connection between a balanced transmission line circuit and an unbalanced transmission line circuit by converting a matching input into a differential output.

[0040] The radio frequency signal received from the antenna is input to the radio frequency input terminal of the double-balanced Gilbert mixer through the low-noise amplification circuit, and the current signal is output through the two cross-conductors below and mixed with the local oscillator signal. The difference frequency signal after mixing is then amplified by a four-way gain-controllable amplification circuit. The amplified signal passes through the I / Q quadrature passive mixer and is mixed with the local oscillator signal again, and finally the intermediate frequency signal is output and amplified and filtered by the TIA.

[0041] Specifically, in one embodiment, the variability of the gain is mainly achieved by turning off a four-channel differential common-source amplifier circuit. By controlling the turn-off of the MOS switch transistors, the subsequent stage is in four states: ① The double-balanced Gilbert mixer, the inter-stage coupling transformer, the first buffer, the inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence. ② The double-balanced Gilbert mixer, the inter-stage coupling transformer, the first buffer, the second buffer, the inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence. ③ The double-balanced Gilbert mixer, the inter-stage coupling transformer, the first buffer, the second buffer, the third buffer, the inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence. ④ The double-balanced Gilbert mixer, the inter-stage coupling transformer, the first buffer, the second buffer, the third buffer, the fourth buffer, the inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence.

[0042] The RF signal simulates the RF signal transmitted from the low-noise amplifier circuit. The single-ended to differential circuit T1 converts this RF signal into a differential output signal, which is then transmitted to the RF input terminal of the double-balanced Gilbert mixer. Current signals are output through the two cross-coupled transistors below and mixed with the local oscillator signal of the Gilbert mixer to output a difference frequency signal, realizing down-conversion. The inter-stage coupling transformers T2 and T3 achieve the matching between different modules, making the input signal a differential signal. The difference frequency signal after the first down-conversion is amplified by a four-channel gain-controllable amplifier circuit. The amplified signal passes through two quadrature passive mixers and is mixed with the local oscillator signal again to output the required intermediate frequency signal. The signal is divided into two differential signals, namely the I-channel and the Q-channel, through the inter-stage coupling transformer T3. These two signals are respectively mixed with the orthogonal local oscillator signals, which can realize the control of the signal phase and amplitude, and reduce the influence of noise and interference signals in the signal processing process. The difference frequency signal generated by the second down-conversion is filtered by the TIA filter and finally the intermediate frequency signal is output. The TIA filter can effectively prevent the leakage of the local oscillator signal and the RF signal, increase the port isolation, and effectively reduce the noise.

[0043] An embodiment of the present invention also provides an electronic device for navigation, which is the mixer described above.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mixer, characterized in that, Comprising: A double-balanced Gilbert mixer, a first inter-stage coupling transformer, a variable-gain buffer, a second inter-stage coupling transformer, an I / Q quadrature passive mixer, and a TIA filter; The double-balanced Gilbert mixer, the first inter-stage coupling transformer, the variable-gain buffer, the second inter-stage coupling transformer, the I / Q quadrature passive mixer, and the TIA filter are electrically connected in sequence; The double-balanced Gilbert mixer is used to receive a differential signal and mix it with the local oscillator signal of the double-balanced Gilbert mixer to achieve the first down-conversion and output a difference frequency signal; the first inter-stage coupling transformer is used for impedance matching between the double-balanced Gilbert mixer and the variable-gain buffer; the variable-gain buffer is used to achieve amplification processing with different gains; the second inter-stage coupling transformer is used for impedance matching between the variable-gain buffer and the I / Q quadrature passive mixer, so that the output signal is a differential signal; The I / Q quadrature passive mixer is used to mix the I-channel and Q-channel signals with the orthogonal local oscillator signals respectively to achieve the second down-conversion and output a difference frequency signal; the TIA filter is used to filter the input difference frequency signal and then output an intermediate frequency signal.

2. The mixer according to claim 1, wherein The double-balanced Gilbert mixer includes: MOS transistor M11, MOS transistor M12, MOS transistor M13, MOS transistor M14, MOS transistor M15, MOS transistor M16, resistor R11, resistor R12, capacitor C11, capacitor C12; The gate of MOS transistor M11 is connected to an output terminal of the previous stage; the source of MOS transistor M11 is grounded; the drain of MOS transistor M11 is respectively connected to the sources of MOS transistor M13 and MOS transistor M14; the gate of MOS transistor M12 is connected to another output terminal of the previous stage; the source of MOS transistor M12 is grounded; the drain of MOS transistor M12 is respectively connected to the sources of MOS transistor M15 and MOS transistor M16; The drains of MOS transistor M13 and MOS transistor M15 are both connected to an input terminal of the next stage, and the drains of MOS transistor M14 and MOS transistor M16 are both connected to another input terminal of the next stage; The gates of MOS transistor M13 and MOS transistor M16 are connected together, and are connected to the reference voltage through resistor R11 and to one end of the local oscillator signal source through capacitor C11; the gates of MOS transistor M14 and MOS transistor M15 are connected together, and are connected to the reference voltage through resistor R12 and to the other end of the local oscillator signal source through capacitor C12.

3. The mixer according to claim 1, characterized in that, The variable gain buffer is composed of multiple identical buffers connected in parallel. Each buffer includes: source negative feedback MOS transistors M21 and M22, MOS transistors M23 and M24, MOS capacitors C21 and C22; the sources of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected together and grounded; the gates of source negative feedback MOS transistor M21 and source negative feedback MOS transistor M22 are connected together and connected to a control signal to achieve variable gain; the drain of source negative feedback MOS transistor M21 is connected to the source of MOS transistor M23, and the drain of source negative feedback MOS transistor M22 is connected to the source of MOS transistor M24; the gate of MOS transistor M23 is connected to one end of MOS capacitor C21 and connected to an output terminal of the previous stage, and the gate of MOS transistor M24 is connected to one end of MOS capacitor C22 and connected to another output terminal of the previous stage; the drain of MOS transistor M23 is connected to the other end of MOS capacitor C22 and connected to an input terminal of the next stage, and the drain of MOS transistor M24 is connected to the other end of MOS capacitor C21 and connected to another input terminal of the next stage.

4. The mixer according to claim 3, wherein The variable gain buffer is composed of 4 buffers connected in parallel.

5. The mixer according to claim 1, characterized in that, The I / Q quadrature passive mixer adopts a two-way design.

6. The mixer according to claim 5, wherein The I / Q quadrature passive mixer adopts a two-way double-balanced design and is composed of two paths connected in parallel; each mixer is the same and includes: MOS transistors M31, M32, M33, and M34; the sources of MOS transistor M31 and MOS transistor M32 are connected together and connected to an output terminal of the second inter-stage coupling transformer; the sources of MOS transistor M33 and MOS transistor M34 are connected together and connected to another output terminal of the second inter-stage coupling transformer; the drains of MOS transistor M31 and MOS transistor M33 are connected together and connected to an input terminal of the next stage; the drains of MOS transistor M32 and MOS transistor M34 are connected together and connected to another input terminal of the next stage; the gates of MOS transistor M31 and MOS transistor M34 are connected together and connected to one end of the local oscillator signal source, and the gates of MOS transistor M32 and MOS transistor M33 are connected together and connected to the other end of the local oscillator signal source.

7. The mixer according to claim 1, characterized in that, The TIA filter adopts a two-way design.

8. The mixer according to claim 7, wherein, The TIA filters all adopt a two-way double-balanced design; they are composed of two paths connected in parallel; each filter is the same and includes: an operational amplifier, MOS transistors M41, M42, M43, M44, M45, M46, resistors R41, R42, R43, R44, R45, and R46; The source of MOS transistor M41 is respectively connected to one end of resistor R41 and one input terminal of the operational amplifier; the drain of MOS transistor M41 is respectively connected to the other end of resistor R41, one end of resistor R42, and the source of MOS transistor M42; the drain of MOS transistor M42 is respectively connected to the other end of resistor R42, one end of resistor R43, and the source of MOS transistor M43; the drain of MOS transistor M43 is respectively connected to the other end of resistor R43 and one output terminal of the operational amplifier; The source of MOS transistor M44 is respectively connected to one end of resistor R44 and the other input terminal of the operational amplifier; the drain of MOS transistor M44 is respectively connected to the other end of resistor R44, one end of resistor R45, and the source of MOS transistor M45; the drain of MOS transistor M45 is respectively connected to the other end of resistor R45, one end of resistor R46, and the source of MOS transistor M46; the drain of MOS transistor M46 is respectively connected to the other end of resistor R46 and the other output terminal of the operational amplifier.

9. The mixer according to claim 1, characterized in that, The differential signal is obtained by output of the single-to-differential unit from the RF signal.

10. The mixer according to claim 9, characterized in that, The single-to-differential unit includes: balun T51, resistor R51, resistor R52; the input terminal of balun T51 is connected to the RF signal input terminal; one output terminal and the other output terminal of balun T51 are respectively connected to the reference voltage through resistor R51 and resistor R52.

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