Four-way Buffer variable gain mixer design

Abstract

The invention provides a four-way Buffer variable gain mixer design. The four-way Buffer variable gain mixer design comprises a double-balanced Gilbert mixer, an interstage first coupling transformer, a variable gain buffer, an interstage second coupling transformer, an I / Q orthogonal passive 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 source 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 invention relates to the field of navigation technology, and in particular to a design of a four-channel buffer variable gain 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 is 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 four-channel buffer variable gain mixer design, aiming to solve the problem in the prior art that the mixer gain, linearity and noise performance cannot be taken into account at the same time.

[0004] The embodiment of the present invention provides a four-channel buffer variable gain mixer design, including: 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 transimpedance amplifier (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 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 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: a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a first resistor, a second resistor, a first capacitor, and a second capacitor;

[0008] The gate of the first MOS tube is connected to an output terminal of the previous stage; the source of the first MOS tube is grounded; the drain of the first MOS tube is respectively connected to the source of the third MOS tube and the source of the fourth MOS tube; the gate of the second MOS tube is connected to the other output terminal of the previous stage; the source of the second MOS tube is grounded; the drain of the second MOS tube is respectively connected to the source of the fifth MOS tube and the source of the sixth MOS tube;

[0009] The drain of the third MOS tube and the drain of the fifth MOS tube are both connected to an input terminal of the next stage, and the drain of the fourth MOS tube and the drain of the sixth MOS tube are both connected to another input terminal of the next stage;

[0010] The gate of the third MOS tube is connected to the gate of the sixth MOS tube, and is connected to the reference voltage through the first resistor and to one end of the local oscillation signal through the first capacitor; the gate of the fourth MOS tube is connected to the gate of the fifth MOS tube, and is connected to the reference voltage through the second resistor and to the other end of the local oscillation signal through the second capacitor.

[0011] Further, the variable gain buffer is formed by connecting multiple buffers in parallel, and each buffer includes: a first source negative feedback MOS tube, a second source negative feedback MOS tube, a first MOS tube, a second MOS tube, a first MOS capacitor and a second MOS capacitor; the source of the first source negative feedback MOS tube and the source of the second source negative feedback MOS tube are connected and grounded; the gate of the first source negative feedback MOS tube and the gate of the second source negative feedback MOS tube are both grounded or connected to a power supply; the drain of the first source negative feedback MOS tube is connected to the source of the first MOS tube, and the drain of the second source negative feedback MOS tube is connected to the source of the second MOS tube; the gate of the first MOS tube is connected to one end of the first MOS capacitor and connected to an output end of the previous stage, and the gate of the second MOS tube is connected to one end of the second MOS capacitor and connected to another output end of the previous stage; the drain of the first MOS tube is connected to the other end of the second MOS capacitor and connected to an input end of the next stage, and the drain of the second MOS tube is connected to the other end of the first MOS capacitor and connected to another input end of the next stage.

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

[0013] Furthermore, the I / Q quadrature passive mixer adopts a two-way double-balanced design.

[0014] Furthermore, the I / Q quadrature passive mixer adopts a two-way double-balanced design, and the two ways are connected in parallel; each mixer includes: a first MOS tube, a second MOS tube, a third MOS tube, and a fourth MOS tube; the source of the first MOS tube is connected to the source of the second MOS tube and connected to an output end of the second coupling transformer between stages; the source of the third MOS tube is connected to the source of the fourth MOS tube and connected to the other output end of the second coupling transformer between stages; the drain of the first MOS tube is connected to the drain of the third MOS tube and connected to an input end of the next stage; the drain of the second MOS tube is connected to the drain of the fourth MOS tube and connected to the other input end of the next stage; the gate of the first MOS tube is connected to the gate of the fourth MOS tube and connected to one end of the local oscillator signal of the next stage, and the gate of the second MOS tube is connected to the gate of the third MOS tube and connected to the other end of the local oscillator signal of the next stage.

[0015] Further, the TIA filter includes: an operational amplifier, a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

[0016] The source of the first MOS tube is respectively connected to one end of the first resistor and an input end of the operational amplifier; the drain of the first MOS tube is respectively connected to the other end of the first resistor, one end of the second resistor and the source of the second MOS tube; the drain of the second MOS tube is respectively connected to the other end of the second resistor, one end of the third resistor and the source of the third MOS tube; the drain of the third MOS tube is respectively connected to the other end of the third resistor and an output end of the operational amplifier;

[0017] The source of the fourth MOS tube is respectively connected to one end of the fourth resistor and the other input end of the operational amplifier; the drain of the fourth MOS tube is respectively connected to the other end of the fourth resistor, one end of the fifth resistor and the source of the fifth MOS tube; the drain of the fifth MOS tube is respectively connected to the other end of the fifth resistor, one end of the sixth resistor and the source of the sixth MOS tube; the drain of the sixth MOS tube is respectively connected to the other end of the sixth resistor and the other output end of the operational amplifier.

[0018] Furthermore, the differential signal is obtained by outputting the radio frequency signal through a single-turn differential unit.

[0019] Furthermore, the single-ended to differential unit includes: a balun, a first resistor, and a second resistor; the input end of the balun is connected to the RF signal input end; one output end and another output end of the balun are connected to a reference voltage through the first resistor and the second resistor, respectively.

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

[0021] A four-channel buffer variable gain mixer design provided by the present invention realizes gain adjustment by adding a variable gain buffer between a double-balanced Gilbert mixer and an I / Q orthogonal passive mixer, and has good linearity and noise performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0024] Figure 2 A circuit diagram of a mixer provided by one embodiment of the present invention;

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

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

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

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

[0029] Figure 7 It is a single-ended to differential unit;

[0030] Figure 8 The linear dynamic range of the mixer output under different conduction conditions of the variable gain buffer is shown in Figure 2. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 , Figure 2As shown, a four-channel buffer variable gain mixer design includes: a double-balanced Gilbert mixer 101, a first interstage coupling transformer 102, a variable gain buffer 103, a second interstage coupling transformer 104, an I / Q orthogonal passive mixer 105 and a TIA filter 106. The double-balanced Gilbert mixer, the first interstage coupling transformer, the variable gain buffer, the second interstage coupling transformer, the I / Q orthogonal passive mixer and the TIA filter are electrically connected in sequence. The double-balanced Gilbert mixer is used to receive the differential signal and mix it with the local oscillator signal of the double-balanced Gilbert mixer to achieve the first down-conversion output of the difference frequency signal; the first interstage coupling transformer is used for 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 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 output of the difference frequency signal; the TIA filter is used to filter the input difference frequency signal and then output the intermediate frequency signal.

[0033] like Figure 3 As shown, the double-balanced Gilbert mixer includes: a first MOS tube M1, a second MOS tube M2, a third MOS tube M3, a fourth MOS tube M4, a fifth MOS tube M5, a sixth MOS tube M6, a first resistor R3, a second resistor R4, a first capacitor, and a second capacitor; the gate of the first MOS tube M1 is connected to an output end of the previous stage; the source of the first MOS tube M1 is grounded; the drain of the first MOS tube M1 is respectively connected to the source of the third MOS tube M3 and the source of the fourth MOS tube M4; the gate of the second MOS tube M2 is connected to the other output end of the previous stage; the source of the second MOS tube M2 is grounded; the drain of the second MOS tube M2 is connected to the The gate of the third MOS tube M3 is connected to the gate of the sixth MOS tube M6, and is connected to the source of the fifth MOS tube M5 and the source of the sixth MOS tube M6 respectively; the drain of the third MOS tube M3 and the drain of the fifth MOS tube M5 are both connected to an input end of the next stage, and the drain of the fourth MOS tube M4 and the drain of the sixth MOS tube M6 are both connected to the other input end of the next stage; the gate of the third MOS tube M3 is connected to the gate of the sixth MOS tube M6, and is connected to the reference voltage through the first resistor R3 and to one end LON of the local oscillation signal through the first capacitor; the gate of the fourth MOS tube M4 is connected to the gate of the fifth MOS tube M5, and is connected to the reference voltage through the second resistor R4 and to the other end LOP of the local oscillation signal through the second capacitor.

[0034] like Figure 4As shown, the variable gain buffer is composed of 4 buffers connected in parallel, and each buffer has the same structure. The bottom one is used for explanation below. This buffer includes: a first source negative feedback MOS tube M21, a second source negative feedback MOS tube M22, a first MOS tube M13, a second MOS tube M14, a first MOS capacitor C7 and a second MOS capacitor C8; the source of the first source negative feedback MOS tube M21 and the source of the second source negative feedback MOS tube M22 are connected and grounded; the gate of the first source negative feedback MOS tube M21 and the gate of the second source negative feedback MOS tube M22 are both grounded or connected to the power supply; the drain of the first source negative feedback MOS tube M21 is connected to the first MOS tube M13. The source of the first MOS tube M21 and the drain of the second source negative feedback MOS tube M22 are connected to the source of the second MOS tube M14; the gate of the first MOS tube M13 is connected to one end of the first MOS capacitor C7 and connected to an output end of the previous stage, and the gate of the second MOS tube M14 is connected to one end of the second MOS capacitor C8 and connected to another output end of the previous stage; the drain of the first MOS tube M13 is connected to the other end of the second MOS capacitor C8 and connected to an input end of the next stage, and the drain of the second MOS tube M14 is connected to the other end of the first MOS capacitor C7 and connected to another input end of the next stage. When the gate of the first source negative feedback MOS tube M21 and the gate of the second source negative feedback MOS tube M22 are both grounded, the MOS is turned off, and the bottom buffer is in a closed state. When the gate of the first source negative feedback MOS tube M21 and the gate of the second source negative feedback MOS tube M22 are both connected to the power supply, the MOS is turned on, and the bottom buffer is in an open state. The variable gain buffer is composed of 4 buffers connected in parallel. By controlling the ground or power supply of each path, the 4 buffers can be turned on with 1, 2, 3, or 4 paths, thereby achieving different gains.

[0035] The I / Q quadrature passive mixer is designed with two paths (i.e., I path and Q path). Figure 5 As shown, the above one is used for explanation; the single-channel orthogonal passive mixer includes: a first MOS tube M35, a second MOS tube M36, a third MOS tube M37, and a fourth MOS tube M38; the source of the first MOS tube M35 is connected to the source of the second MOS tube M36 and connected to an output end of the second coupling transformer between stages; the source of the third MOS tube M37 is connected to the source of the fourth MOS tube M38 and connected to the other output end of the second coupling transformer between stages; the drain of the first MOS tube M35 is connected to the drain of the third MOS tube M37 and connected to an input end of the next stage; the drain of the second MOS tube M36 is connected to the drain of the fourth MOS tube M38 and connected to the other input end of the next stage; the gate of the first MOS tube M35 is connected to the gate of the fourth MOS tube M38 and connected to one end LO1 of the local oscillation signal, and the gate of the second MOS tube is connected to the gate of the third MOS tube and connected to the other end LO2 of the local oscillation signal.

[0036] The TIA filter also adopts the I / Q two-way design. Figure 6 As shown, the above one is used for explanation; the single-channel TIA filter includes: an operational amplifier, a first MOS tube M23, a second MOS tube M24, a third MOS tube M25, a fourth MOS tube M26, a fifth MOS tube M27, a sixth MOS tube M28, a first resistor R5, a second resistor R6, a third resistor R7, a fourth resistor R8, a fifth resistor R9, and a sixth resistor R10; the source of the first MOS tube M23 is respectively connected to one end of the first resistor and an input end of the operational amplifier; the drain of the first MOS tube M23 is respectively connected to the other end of the first resistor R5, one end of the second resistor R6 and the source of the second MOS tube M24; the drain of the second MOS tube M24 is respectively connected to the other end of the second resistor R6 The drain of the third MOS tube M25 is respectively connected to the other end of the third resistor R7 and an output end of the operational amplifier; the source of the fourth MOS tube M26 is respectively connected to one end of the fourth resistor R8 and the other input end of the operational amplifier; the drain of the fourth MOS tube M26 is respectively connected to the other end of the fourth resistor R8, one end of the fifth resistor R9 and the source of the fifth MOS tube M27; the drain of the fifth MOS tube M27 is respectively connected to the other end of the fifth resistor R9, one end of the sixth resistor R10 and the source of the sixth MOS tube M28; the drain of the sixth MOS tube M28 is respectively connected to the other end of the sixth resistor R10 and the other output end of the operational amplifier.

[0037] When the mixer is used for navigation, the front end receives a radio frequency signal, which needs to be converted into a differential signal. Therefore, a single-to-differential unit is provided in the previous stage of the double-balanced Gilbert mixer 101 to convert the radio frequency signal into a differential signal and output it to the double-balanced Gilbert mixer 101.

[0038] like Figure 7 As shown, the single-ended to differential unit includes: a balun T1, a first resistor R1, and a second resistor R2; the input end of the balun T1 is connected to the RF signal input end RF; one output end and the other output end of the balun are connected to the reference voltage through the first resistor R1 and the second resistor R2 respectively. The balun is a broadband RF 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.

[0039] The RF signal received from the antenna is input to the RF input end of the double-balanced Gilbert mixer through a low-noise amplifier circuit, and the current signal is output through the two transconductors below and mixed with the local oscillator signal. The difference frequency signal after mixing is amplified by a four-way gain-controllable amplifier circuit. The amplified signal passes through an I / Q orthogonal 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.

[0040] Specifically, in the embodiment, the gain variability is mainly achieved by turning off the four-way differential common source amplifier circuit, and the MOS switch tube is controlled to be turned off so that the subsequent stage is in four states: ① the double-balanced Gilbert mixer, the interstage coupling transformer, the first buffer, the interstage coupling transformer, the I / Q orthogonal passive mixer, and the TIA filter are electrically connected in sequence; ② the double-balanced Gilbert mixer, the interstage coupling transformer, the first buffer, the second buffer, the interstage coupling transformer, the I / Q orthogonal passive mixer, and the TIA filter are electrically connected in sequence; ③ the double-balanced Gilbert mixer, the interstage coupling transformer, the first buffer, the second buffer, the third buffer, the interstage coupling transformer, the I / Q orthogonal passive mixer, and the TIA filter are electrically connected in sequence; ④ the double-balanced Gilbert mixer, the interstage coupling transformer, the first buffer, the second buffer, the third buffer, the fourth buffer, the interstage coupling transformer, the I / Q orthogonal passive mixer, and the TIA filter are electrically connected in sequence.

[0041] The RF signal simulates the RF signal transmitted from the low-noise amplifier circuit. The RF signal is converted into a differential output signal through the single-turn differential circuit T1, and then transmitted to the RF input end of the double-balanced Gilbert mixer. The current signal is output through the two transconductors below, and mixed with the local oscillator signal source of the Gilbert mixer to output the difference frequency signal to achieve down-conversion. The interstage coupling transformers T2 and T3 achieve the matching between different modules, so that the input signal is a differential signal. The difference frequency signal after the first down-conversion is amplified by a four-way gain-controllable amplifier circuit. The amplified signal passes through two orthogonal passive mixers and is mixed with the local oscillator signal again to produce the required intermediate frequency signal. The signal is divided into two differential signals, I and Q, through the interstage coupling transformer T3. These two signals are mixed with the orthogonal local oscillator signal respectively, 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 secondary down-conversion is filtered by the TIA filter and finally outputs the intermediate frequency signal. TIA filters can effectively prevent the leakage of local oscillator signals and RF signals and increase port isolation.

[0042] NMOS tube M1, NMOS tube M3, NMOS tube M5, NMOS tube M7, NMOS tube M9, NMOS tube M11, NMOS tube M13, NMOS tube M15 are all switch tubes controlled by gate voltage. Taking M13 and M15 switch tubes as an example, DGND is grounded or connected to the power supply. When DGND is connected to the power supply, M13 and M15 switch tubes are turned on, and the drain voltage of M13 and M15 tubes is pulled down, so that the drain potential is close to 0, which causes the gate-source voltage of the differential common source circuit to exceed the threshold voltage of M14 and M16. At this time, the MOS tube is in the on state, the buffer is in the on state, and the gain increases; when DGND is grounded, the M13 and M15 switch tubes are cut off, and almost no current is generated in the circuit, which causes the gate-source voltage of the differential common source circuit to be very small, the MOS tube cannot be turned on, the buffer is in the off state, and the gain decreases.

[0043] In these four states, the input matching performance and output of the four-way buffer will not be affected by the change in circuit structure. Table 1 summarizes the comparison of the buffer gain and TIA output when the four-way buffer circuit is turned on or off. From the data in the table, it can be seen that as the number of conduction paths in each buffer changes, the gain of the entire receiving link is also significantly improved.

[0044] Table 1 Comparison of Buffer gain and TIA output

[0045]

[0046] Since the input RF signal of the mixer is amplified by the low noise amplifier, the RF signal sent to the mixer is always larger than the signal input to the LNA. Therefore, the linearity index of the mixer is higher than that of the low noise amplifier. Figure 8 The linear dynamic range curve of the mixer output is simulated when the four-way buffer circuit is turned on or off. The solid line represents the case of the four-way buffer circuit, the dotted line represents the case of the three-way buffer circuit, the short dash line represents the case of the two-way buffer circuit, and the dotted line represents the case of the one-way buffer circuit. It can be seen from the data in the figure that when the input is -30dBm, the dynamic range reaches 30dB.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A four-channel buffer variable gain mixer design, characterized in that: include: Double balanced Gilbert mixer, interstage first coupling transformer, variable gain buffer, interstage second coupling transformer, I / Q quadrature passive mixer and trans-impedance amplifier (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 orthogonal 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 source of the double-balanced Gilbert mixer to achieve the first down-conversion and output the 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 orthogonal passive mixer, so that the output signal is a differential signal; The I / Q orthogonal passive mixer is used to mix the I and Q signals with the orthogonal local oscillator signals respectively to achieve a second down-conversion output 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, characterized in that The double-balanced Gilbert mixer includes: a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a first resistor, a second resistor, a first capacitor, and a second capacitor; The gate of the first MOS tube is connected to an output terminal of the previous stage; the source of the first MOS tube is grounded; the drain of the first MOS tube is respectively connected to the source of the third MOS tube and the source of the fourth MOS tube; the gate of the second MOS tube is connected to the other output terminal of the previous stage; the source of the second MOS tube is grounded; the drain of the second MOS tube is respectively connected to the source of the fifth MOS tube and the source of the sixth MOS tube; The drain of the third MOS tube and the drain of the fifth MOS tube are both connected to an input terminal of the next stage, and the drain of the fourth MOS tube and the drain of the sixth MOS tube are both connected to another input terminal of the next stage; The gate of the third MOS tube is connected to the gate of the sixth MOS tube, and is connected to the reference voltage through the first resistor and to one end of the local oscillation signal through the first capacitor; the gate of the fourth MOS tube is connected to the gate of the fifth MOS tube, and is connected to the reference voltage through the second resistor and to the other end of the local oscillation signal through the second capacitor.

3. The mixer according to claim 1, characterized in that The variable gain buffer is formed by connecting multiple buffers in parallel, and each buffer includes: a first source negative feedback MOS tube, a second source negative feedback MOS tube, a first MOS tube, a second MOS tube, a first MOS capacitor and a second MOS capacitor; the source of the first source negative feedback MOS tube is connected to the source of the second source negative feedback MOS tube and is grounded; the gate of the first source negative feedback MOS tube is connected to the gate of the second source negative feedback MOS tube and is connected to a high / low level; the drain of the first source negative feedback MOS tube is connected to the source of the first MOS tube, and the drain of the second source negative feedback MOS tube is connected to the source of the second MOS tube; the gate of the first MOS tube is connected to one end of the first MOS capacitor and is connected to an output end of the previous stage, and the gate of the second MOS tube is connected to one end of the second MOS capacitor and is connected to another output end of the previous stage; the drain of the first MOS tube is connected to the other end of the second MOS capacitor and is connected to an input end of the next stage, and the drain of the second MOS tube is connected to the other end of the first MOS capacitor and is connected to another input end of the next stage.

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

5. The mixer according to claim 1, characterized in that: The I / Q quadrature passive mixer and the TIA filter both adopt a two-way double-balanced design.

6. The mixer according to claim 5, characterized in that The I / Q quadrature passive mixer adopts a two-way double-balanced design, and the two ways are connected in parallel; each mixer is the same and includes: a first MOS tube, a second MOS tube, a third MOS tube, and a fourth MOS tube; the source of the first MOS tube is connected to the source of the second MOS tube and connected to an output end of the second coupling transformer between stages; the source of the third MOS tube is connected to the source of the fourth MOS tube and connected to the other output end of the second coupling transformer between stages; the drain of the first MOS tube is connected to the drain of the third MOS tube and connected to an input end of the next stage; the drain of the second MOS tube is connected to the drain of the fourth MOS tube and connected to the other input end of the next stage; the gate of the first MOS tube is connected to the gate of the fourth MOS tube and connected to one end of the local oscillator signal of the next stage, and the gate of the second MOS tube is connected to the gate of the third MOS tube and connected to the other end of the local oscillator signal of the next stage.

7. The mixer according to claim 1, characterized in that The TIA filter comprises: an operational amplifier, a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; The source of the first MOS tube is respectively connected to one end of the first resistor and an input end of the operational amplifier; the drain of the first MOS tube is respectively connected to the other end of the first resistor, one end of the second resistor and the source of the second MOS tube; the drain of the second MOS tube is respectively connected to the other end of the second resistor, one end of the third resistor and the source of the third MOS tube; the drain of the third MOS tube is respectively connected to the other end of the third resistor and an output end of the operational amplifier; The source of the fourth MOS tube is respectively connected to one end of the fourth resistor and the other input end of the operational amplifier; the drain of the fourth MOS tube is respectively connected to the other end of the fourth resistor, one end of the fifth resistor and the source of the fifth MOS tube; the drain of the fifth MOS tube is respectively connected to the other end of the fifth resistor, one end of the sixth resistor and the source of the sixth MOS tube; the drain of the sixth MOS tube is respectively connected to the other end of the sixth resistor and the other output end of the operational amplifier.

8. The mixer according to claim 1, characterized in that The differential signal is obtained by outputting the radio frequency signal through a single-turn differential unit.

9. The amplifier according to claim 1, characterized in that The single-ended to differential unit comprises: a balun, a first resistor, and a second resistor; the input end of the balun is connected to the radio frequency signal input end; one output end and the other output end of the balun are connected to a reference voltage through the first resistor and the second resistor, respectively.

10. An electronic device for navigation, characterized in that: Use the mixer described in any one of claims 1 to 9.

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