A microwave sensor and its control circuit

Abstract

The present invention discloses a microwave sensor and a control circuit thereof. The control circuit of the microwave sensor comprises a communication unit, a control unit, and an antenna unit and a signal amplifying unit respectively electrically connected to the control unit; the antenna unit is used to transmit and receive antenna signals, the signal amplifying unit is used to process the antenna signal transmitted by the antenna unit and feed it back to the control unit, and the control unit transmits the processed antenna signal to an external controller through the communication unit; the signal amplifying unit comprises an absorbing part, the absorbing part is used to absorb clutter signals in the antenna signal transmitted by the antenna unit, and the absorbing part is connected to the signal output end of the antenna unit; the control circuit of the microwave sensor provided by the present invention absorbs clutter signals in the antenna signal transmitted by the antenna unit through the absorbing part in the signal amplifying unit, reduces interference signals in the antenna signal, and improves the detection accuracy of the microwave sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a microwave sensor and a control circuit thereof. Background Art

[0002] Microwave sensors are devices that use the characteristics of microwaves to detect certain physical quantities, including the presence, speed, distance, angle and other information of sensing objects. Microwaves are emitted by the transmitting antenna, and when the emitted microwaves encounter the object to be measured, they are absorbed or reflected, causing the power to change. The receiving antenna receives the microwaves that pass through the object to be measured or are reflected back by the object to be measured, and converts them into electrical signals, which are then processed by the measuring circuit to achieve microwave detection.

[0003] In existing microwave sensors, the signal received by the receiving antenna is mixed with a lot of clutter signals, resulting in a problem of poor detection accuracy.

[0004] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a control circuit of a microwave sensor, which absorbs the clutter signal in the antenna signal transmitted by the antenna unit through an absorbing part, reduces the interference signal in the antenna signal, and improves the detection accuracy of the microwave sensor.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A control circuit of a microwave sensor comprises a communication unit, a control unit, and an antenna unit and a signal amplifying unit electrically connected to the control unit respectively; the antenna unit is used to transmit and receive antenna signals, the signal amplifying unit is used to process the antenna signal transmitted by the antenna unit and feed it back to the control unit, and the control unit is used to transmit the processed antenna signal to an external controller through the communication unit; the signal amplifying unit comprises an absorbing part, the absorbing part is used to absorb clutter signals in the antenna signal transmitted by the antenna unit, and the absorbing part is connected to the signal output end of the antenna unit.

[0008] The control circuit of the microwave sensor further comprises a power supply unit, which is electrically connected to the control unit, the antenna unit, the signal amplifying unit and the communication unit respectively.

[0009] In the control circuit of the microwave sensor, the power supply unit includes a first voltage stabilizing filter unit and a second voltage stabilizing filter unit, the first voltage stabilizing filter unit is electrically connected to the control unit, and the second voltage stabilizing filter unit is electrically connected to the antenna unit and the signal amplifying unit respectively.

[0010] In the control circuit of the microwave sensor, the signal amplifying unit also includes a first amplifying unit, a second amplifying unit and a third amplifying unit; the antenna signal transmitted by the antenna unit is processed by the first amplifying unit, the second amplifying unit and the third amplifying unit in sequence and then output to the control unit after the antenna signal is absorbed by the absorbing unit.

[0011] In the control circuit of the microwave sensor, the power supply unit also includes a third voltage stabilizing filter unit, the input end of the third voltage stabilizing filter unit is connected to the output end of the second voltage stabilizing filter unit, and the output end of the third voltage stabilizing filter unit is respectively connected to the first amplifier unit and the second amplifier unit.

[0012] In the control circuit of the microwave sensor, the control unit includes a first control unit, the first control unit is electrically connected to the third amplifying unit, and the first control unit is used to control the third amplifying unit to start or stop working.

[0013] In the control circuit of the microwave sensor, the first amplifier includes a first negative feedback circuit, and the second amplifier includes a second negative feedback circuit; the first negative feedback circuit is used to reduce the error of the signal output by the first amplifier, and the second negative feedback circuit is used to reduce the error of the signal output by the second amplifier.

[0014] In the control circuit of the microwave sensor, the control unit further includes a second control unit, the second control unit is electrically connected to the antenna unit, and the second control unit is used to control the antenna unit to start or stop working.

[0015] In the control circuit of the microwave sensor, the control unit further comprises a signal output unit, and the signal output unit is electrically connected to the communication unit.

[0016] The present invention also provides a microwave sensor accordingly, including a shell, a PCB board is arranged in the shell, the control circuit of the microwave sensor is printed on the PCB board, and a transmitting antenna disk and a receiving antenna disk are also arranged on the PCB board, and the transmitting antenna disk and the receiving antenna disk are electrically connected to the control circuit of the microwave sensor respectively.

[0017] Beneficial effects:

[0018] The present invention provides a microwave sensor and a control circuit thereof. The control circuit of the microwave sensor includes a signal amplifying unit. The absorbing part in the signal amplifying unit absorbs the clutter signal in the antenna signal transmitted by the antenna unit, thereby reducing the interference signal in the antenna signal and improving the detection accuracy of the microwave sensor. In addition, the first amplifying part includes a first negative feedback circuit, and the second amplifying part includes a second negative feedback circuit, which can reduce the error of the signal output by the first amplifying part and the signal output by the second amplifying part, thereby further improving the accuracy and reliability of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a control circuit of a microwave sensor provided by the present invention;

[0020] Figure 2 A circuit structure diagram of a control unit provided by the present invention;

[0021] Figure 3 A circuit structure diagram of a power supply unit provided by the present invention;

[0022] Figure 4 A circuit structure diagram of the antenna unit provided by the present invention;

[0023] Figure 5 A circuit structure diagram of a signal amplification unit provided by the present invention;

[0024] Figure 6 A circuit structure diagram of the third voltage stabilizing and filtering unit provided by the present invention;

[0025] Figure 7 A circuit structure diagram of a first control unit provided by the present invention;

[0026] Figure 8 A circuit structure diagram of a second control unit provided by the present invention;

[0027] Fig. 9 This is a circuit structure diagram of the communication unit provided by the present invention. DETAILED DESCRIPTION

[0028] The present invention provides a microwave sensor and a control circuit thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0029] In the description of the present invention, it should be understood that the terms "installation", "connection" and the like should be understood in a broad sense, and a person skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0030] See also Figure 1The present invention provides a control circuit of a microwave sensor, comprising a communication unit, a control unit, and an antenna unit and a signal amplifying unit electrically connected to the control unit respectively; the antenna unit is used to transmit and receive antenna signals, the signal amplifying unit is used to process the antenna signal transmitted by the antenna unit and feed it back to the control unit, and the control unit is used to transmit the processed antenna signal to an external controller through the communication unit; the signal amplifying unit comprises an absorbing part, the absorbing part is used to absorb clutter signals in the antenna signal transmitted by the antenna unit, and the absorbing part is connected to the signal output end of the antenna unit.

[0031] The external controller is used to receive the processed antenna signal fed back by the control unit, and further control the operation of the corresponding components, mechanisms or devices according to the processed antenna signal; for example, a microwave sensor including the control circuit of the above-mentioned microwave sensor is set on a refrigerator, and the external controller refers to a controller set in the refrigerator and used to control and adjust the working state of the refrigerator.

[0032] The present invention provides a control circuit of a microwave sensor, which absorbs clutter signals in antenna signals transmitted by an antenna unit through an absorption part in a signal amplification unit, reduces interference signals in the antenna signal, and improves the detection accuracy of the microwave sensor.

[0033] In one embodiment, see Figure 5 The absorption part includes a thirteenth capacitor C13, a fourteenth capacitor C14, an eleventh resistor R11 and a twelfth resistor R12; the thirteenth capacitor C13 and the eleventh resistor R11 are connected in series to form a first absorption part, and the fourteenth capacitor C14 and the twelfth resistor R12 are connected in series to form a second absorption part; the input end of the first absorption part and the input end of the second absorption part are respectively connected to the antenna unit; the first absorption part and the second absorption part cooperate to effectively absorb the clutter signal in the antenna signal transmitted by the antenna unit, thereby reducing the influence of the interference signal on the detection result.

[0034] In one embodiment, see Figure 2 The control unit includes a first control chip U1 and a first capacitor C1; the first control chip U1 is a single-chip control chip of model SC92F7250, one end of the first capacitor C1 is connected to pin 1 of the first control chip U1, and the other end of the first capacitor C1 is connected to pin 8 of the first control chip U1, and the first capacitor C1 plays a filtering role.

[0035] For further information, see Figure 1 as well as Figures 3 to 5 The control circuit of the microwave sensor also includes a power supply unit, which is electrically connected to the control unit, the antenna unit, the signal amplifying unit and the communication unit respectively.

[0036] For further information, see Figures 3 to 5 The power supply unit includes a first voltage stabilizing filter unit and a second voltage stabilizing filter unit, the first voltage stabilizing filter unit is electrically connected to the control unit, and the second voltage stabilizing filter unit is electrically connected to the antenna unit and the signal amplifying unit respectively.

[0037] In one embodiment, see Figure 4 , the antenna unit includes a second control chip U2, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11 and a twelfth capacitor C12; the second control chip U2 is a millimeter wave radar chip, and the model of the second control chip U2 can be but is not limited to SG24TR12; one end of the ninth capacitor C9 is respectively connected to the pin 3 and the pin 30 of the second control chip U2, and the other end of the ninth capacitor C9 is grounded; one end of the tenth capacitor C10 is respectively connected to the pin 3 and the pin 30 of the second control chip U2, and the other end of the tenth capacitor C10 is grounded; the ninth capacitor C9 and the tenth capacitor C10 are connected to the pin 3 and the pin 30 of the second control chip U2, and the other end of the tenth capacitor C10 is grounded; Capacitor C10 plays a filtering role; one end of the eleventh capacitor C11 and the twelfth capacitor C12 are respectively connected to pin 9 of the second control chip U2, and the other ends of the eleventh capacitor C11 and the twelfth capacitor C12 are grounded; the eleventh capacitor C11 and the twelfth capacitor C12 play a filtering role; pin 18 of the second control chip U2 is an antenna signal receiving port, pin 28 of the second control chip U2 is an antenna signal transmitting port, pin 14 of the second control chip U2 is connected to the input end of the second absorption part, and pin 15 of the second control chip U2 is connected to the input end of the first absorption part.

[0038] See also Figure 3 In one embodiment, the first voltage stabilization and filtering unit includes a twentieth capacitor C20 and a third control chip U3, and the model of the third control chip U3 is ME6211C33M5G-N; one end of the twentieth capacitor C20 is grounded, and the other end of the twentieth capacitor C20 is respectively connected to pin 1 and pin 3 of the third control chip U3, and the twentieth capacitor C20 plays a filtering role; the third control chip U3 stabilizes the external input voltage VIN to a 3.3V voltage output, and the external input voltage VIN can be AC ​​power; pin 5 of the third control chip U3 is connected to pin 8 of the first control chip U1 of the control unit.

[0039] See also Figure 3In one embodiment, the second voltage stabilization and filtering unit includes a nineteenth capacitor C19, a fourth control chip U4, a first inductor L1 and a second inductor L2, and the model of the fourth control chip is ME6211C25M5G-N; one end of the nineteenth capacitor C19 is grounded, and the other end of the nineteenth capacitor C19 is respectively connected to pin 1 and pin 3 of the fourth control chip U4, and the nineteenth capacitor C19 plays a filtering role; the fourth control chip U4 stabilizes the external input voltage VIN to 2.5V output, and the external input voltage VIN can be AC ​​power; the pin 5 of the fourth control chip U4 is respectively connected to the signal amplification unit and the antenna unit; the first inductor L1 is connected in series between the pin 5 of the fourth control chip U4 and the signal amplification unit, and plays a filtering role; the second inductor L2 is connected in series between the pin 5 of the fourth control chip U4 and the antenna unit, and plays a filtering role, and the pin 5 of the fourth control chip U4 is respectively connected to the pin 9, pin 16 and pin 25 in the second control chip U2 of the antenna unit.

[0040] For further information, see Figure 4 and Figure 5 The signal amplifying unit further includes a first amplifying unit, a second amplifying unit and a third amplifying unit; the antenna signal transmitted by the antenna unit is processed by the first amplifying unit, the second amplifying unit and the third amplifying unit in sequence after the clutter signal is absorbed by the absorbing unit, and then output to the control unit; the first amplifying unit plays a primary amplifying role, the second amplifying unit plays a secondary amplifying role, and the third amplifying unit plays a tertiary amplifying role and outputs the processed signal to the control unit.

[0041] In one embodiment, see Figure 5 The first amplifying part includes a first operational amplifier UA1, a fourteenth resistor R14 and a sixteenth capacitor C16; the output end of the first absorbing part is connected to pin 2 of the first operational amplifier UA1, the output end of the second absorbing part is connected to pin 3 of the first operational amplifier UA1, pin 5 of the first operational amplifier UA1 is grounded, pin 1 of the first operational amplifier UA1 is a signal output end, pin 1 of the first operational amplifier UA1 is connected to the second amplifying part, and pin 4 of the first operational amplifier UA1 is connected to the second filtering and stabilizing part of the power supply unit; one end of the fourteenth resistor R14 and the sixteenth capacitor C16 are respectively connected to pin 3 of the first operational amplifier UA1, and the other ends of the fourteenth resistor R14 and the sixteenth capacitor C16 are connected to the power supply unit, the fourteenth resistor R14 plays a current limiting role, and the sixteenth capacitor C16 plays a filtering role.

[0042] In one embodiment, see Figure 5The second amplifying part includes a second operational amplifier UB1, a seventeenth capacitor C17 and a fifteenth resistor R15; pin 2 of the second operational amplifier UB1 is connected to pin 1 of the first operational amplifier UA1, pin 3 of the second operational amplifier UB1 is connected to the power supply unit, pin 4 of the second operational amplifier UB1 is connected to the second filtering and voltage stabilizing part of the power supply unit, pin 5 of the second operational amplifier UB1 is grounded, pin 1 of the second operational amplifier UB1 is a signal output terminal, and pin 1 of the second operational amplifier UB1 is connected to the third amplifying part; the seventeenth capacitor C17 and the fifteenth resistor R15 are connected in series between pin 1 of the first operational amplifier UA1 and pin 2 of the second operational amplifier UB1, and the seventeenth capacitor C17 and the fifteenth resistor R15 couple the signal output by the first operational amplifier UA1 to the second operational amplifier UB1.

[0043] In one embodiment, see Figure 5 The third amplifying part includes a third operational amplifier UC1 and a seventeenth resistor R17; Pin 2 of the third operational amplifier UC1 is connected to Pin 1 of the second operational amplifier UB1, Pin 3 of the third operational amplifier UC1 is connected to the power supply unit, Pin 4 of the third operational amplifier UC1 is connected to the second filtering and voltage stabilizing part of the power supply unit, Pin 5 of the third operational amplifier UC1 is grounded, Pin 1 of the third operational amplifier UC1 is a signal output terminal, Pin 1 of the third operational amplifier UC1 is connected to Pin 7 of the first control chip U1 in the control unit; The seventeenth resistor R17 is connected in series between Pin 1 of the third operational amplifier UC1 and Pin 7 of the first control chip U1, and the seventeenth resistor R17 plays a current limiting role.

[0044] For further information, see Figure 5 and Figure 6 The power supply unit also includes a third voltage stabilizing filter unit, the input end of the third voltage stabilizing filter unit is connected to the output end of the second voltage stabilizing filter unit, and the output end of the third voltage stabilizing filter unit is respectively connected to the first amplifier unit and the second amplifier unit; the third voltage stabilizing filter unit is used to provide a stable operating voltage for the first amplifier unit and the second amplifier unit.

[0045] In one embodiment, see Figure 6The third voltage stabilizing filter unit includes a twenty-second capacitor C22, a twenty-third capacitor C23, a twenty-fourth capacitor C24, an eighteenth resistor R18 and a nineteenth resistor R19, the twenty-second capacitor C22, the twenty-third capacitor C23, the twenty-fourth capacitor C24 and the nineteenth resistor R19 are connected in parallel, and the eighteenth capacitor is connected in series between the twenty-third capacitor C23 and the nineteenth resistor R19; the input end of the third voltage stabilizing filter unit is connected to the second voltage stabilizing filter unit, and the output end of the third voltage stabilizing filter unit is respectively connected to pin 3 of the first operational amplifier UA1 and pin 3 of the second operational amplifier UB1.

[0046] For further information, see Figure 5 and Figure 7 The control unit includes a first control unit, the first control unit is electrically connected to the third amplifying unit, and the first control unit is used to control the third amplifying unit to start or stop working.

[0047] In one embodiment, see Figure 7 , the first control unit includes a fifth capacitor C5, a current capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10; the fifth capacitor C5, the current capacitor C6, the seventh capacitor C7, the eighth capacitor C8 and the tenth resistor R10 are connected in parallel, the seventh resistor R7 is connected in series with the fifth capacitor C5, the eighth resistor R8 is connected in series between the fifth capacitor C5 and the sixth capacitor C6, and the ninth resistor R9 is connected in series between the sixth capacitor C6 and the seventh capacitor C7; the input end of the first control unit is connected to the pin 5 of the first control chip U1, and the output end of the first control unit is connected to the pin 3 of the third operational amplifier UC1; the first control chip U1 can change the voltage signal output to the third operational amplifier UC1 by adjusting the duty cycle of PWM, that is, the first control chip U1 realizes the working control of the third amplifier by adjusting the high and low level signals outputted by it.

[0048] For further information, see Figure 5 The first amplifier unit includes a first negative feedback circuit, and the second amplifier unit includes a second negative feedback circuit; the first negative feedback circuit is used to reduce the error of the signal output by the first amplifier unit, and the second negative feedback circuit is used to reduce the error of the signal output by the second amplifier unit.

[0049] In one embodiment, see Figure 5The first negative feedback circuit includes a fifteenth capacitor C15 and a thirteenth resistor R13 connected in parallel, one end of the thirteenth resistor R13 is connected to pin 2 of the first operational amplifier UA1, and the other end of the thirteenth resistor R13 is connected to pin 1 of the first operational amplifier UA1; the first negative feedback circuit feeds back the output signal of the first operational amplifier UA1 to the signal output end of the first operational amplifier UA1, so that the closed-loop gain of the first operational amplifier UA1 tends to be stable, eliminates the influence of the open-loop gain, and improves the stability of the signal output by the first operational amplifier UA1.

[0050] In one embodiment, see Figure 5 The second negative feedback circuit includes an eighteenth capacitor C18 and a sixteenth resistor R16 connected in parallel, one end of the sixteenth resistor R16 is connected to pin 2 of the second operational amplifier UB1, and the other end of the sixteenth resistor R16 is connected to pin 1 of the second operational amplifier UB1; the second negative feedback circuit feeds back the output signal of the second operational amplifier UB1 to the signal output end of the second operational amplifier UB1, so that the closed-loop gain of the second operational amplifier UB1 tends to be stable, eliminates the influence of the open-loop gain, and improves the stability of the signal output by the second operational amplifier UB1.

[0051] For further information, see Figure 8 The control unit also includes a second control unit, which is electrically connected to the antenna unit and is used to control the antenna unit to start or stop working.

[0052] In one embodiment, see Figure 8 The second control unit is a 3rd-order RC low-pass filter circuit, and the second control unit includes a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are connected in parallel, the fourth resistor R4 is connected in series between the second capacitor C2 and the third capacitor C3, the fifth resistor R5 is connected in series between the third capacitor C3 and the fourth capacitor C4, and the sixth resistor R6 is connected in series with the fourth capacitor C4; the input end of the second control unit is connected to the pin 4 of the first control chip U1, and the output end of the second control unit is connected to the pin 23 of the second control chip U2 of the antenna unit; the first control chip U1 can change the voltage signal output to the second control chip U2 by adjusting the duty cycle of PWM, that is, the first control chip U1 realizes the working control of the second control chip U2 by adjusting the high and low level signals output by it.

[0053] For further information, see Figure 2 and Fig. 9 , the control unit also includes a signal output unit, and the signal output unit is electrically connected to the communication unit.

[0054] In one embodiment, see Figure 2 The signal output part includes a first resistor R1, a second resistor R2, a third resistor R3 and a first transistor Q1; one end of the first resistor R1 is connected to the pin 6 of the first control chip U1, and the other end of the first resistor R1 is connected to the base of the first transistor Q1; one end of the second resistor R2 is connected to the base of the first transistor Q1, and the other end of the second resistor R2 is grounded; the emitter of the first transistor Q1 is grounded, and the emitter of the first transistor Q1 is respectively connected to the communication unit and one end of the third resistor R3, and the other end of the third resistor R3 is connected to the external input voltage VIN, and the external input voltage VIN can be AC ​​power.

[0055] In one embodiment, see Fig. 9 The communication unit includes a communication port P1, a twentieth resistor R20 and a twenty-first resistor R21; pin 1 of the communication port P1 is connected to an external input voltage VIN, pin 2 of the communication port P1 is grounded, pin 3 of the communication port P1 is connected to pin 3 of a first control chip U1 in a control unit, pin 4 of the communication port P1 is connected to a collector of a first transistor Q1, and pin 5 of the communication port P1 is connected to pin 2 of the first control chip U1 in a control unit; the twentieth resistor R20 is connected in series with pin 3 of the communication port P1, the twenty-first resistor R21 is connected in series with pin 5 of the communication port P1, and the twentieth resistor R20 and the twenty-first resistor R21 play a current limiting role; pin 3 of the communication port P1 is a serial port data sending end, and pin 5 of the communication port P1 is a serial port data receiving end.

[0056] The communication unit is connected to an external controller, and the control unit transmits the processed antenna signal to the external controller through the communication unit. The external controller controls and adjusts the working state of the corresponding device according to the received signal. For example, a microwave sensor is set on the refrigerator. When the microwave sensor detects that someone is approaching, the antenna signal emitted by the antenna unit is blocked, and the antenna signal received by the antenna unit changes. The antenna unit first processes the received antenna signal through the signal amplification unit, and then outputs it to the control unit. The control unit outputs the antenna signal to the external controller through the communication unit. The external controller controls the brightness of the display screen on the refrigerator to increase, so that the user can check the internal environment of the refrigerator and adjust the working state of the refrigerator by display screen control.

[0057] The present invention also provides a microwave sensor accordingly, including a shell, a PCB board is arranged in the shell, the control circuit of the microwave sensor is printed on the PCB board, and a transmitting antenna disk and a receiving antenna disk are also arranged on the PCB board, and the transmitting antenna disk and the receiving antenna disk are electrically connected to the control circuit of the microwave sensor respectively; specifically, the transmitting antenna disk is connected to the pin 28 of the second control chip U2 in the antenna unit, and the transmitting antenna disk is used to transmit antenna signals; the receiving antenna disk is connected to the pin 18 of the second control chip U2 in the antenna unit, and the receiving antenna disk is used to receive antenna signals.

[0058] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A control circuit of a microwave sensor, comprising a communication unit, characterized in that: It also includes a control unit, and an antenna unit and a signal amplifying unit electrically connected to the control unit respectively; the antenna unit is used to transmit and receive antenna signals, the signal amplifying unit is used to process the antenna signal transmitted by the antenna unit and feed it back to the control unit, and the control unit is used to transmit the processed antenna signal to an external controller through the communication unit; the signal amplifying unit includes an absorbing part, the absorbing part is used to absorb the clutter signal in the antenna signal transmitted by the antenna unit, and the absorbing part is connected to the signal output end of the antenna unit; The control unit includes a first control chip U1 and a first capacitor C1; the first control chip U1 is a SC92F7250, one end of the first capacitor C1 is connected to pin 1 of the first control chip U1, and the other end of the first capacitor C1 is connected to pin 8 of the first control chip U1; The signal amplifying unit further comprises a first amplifying unit, a second amplifying unit and a third amplifying unit; the antenna signal transmitted by the antenna unit is processed by the first amplifying unit, the second amplifying unit and the third amplifying unit in sequence and then output to the control unit after the clutter signal is absorbed by the absorbing unit; The control unit includes a first control unit, an input end of the first control unit is connected to pin 5 of the first control chip U1, the first control unit is electrically connected to the third amplifier, and the first control unit is used to control the third amplifier to start or stop working.

2. A control circuit for a microwave sensor according to claim 1, characterized in that: It also includes a power supply unit, which is electrically connected to the control unit, the antenna unit, the signal amplifying unit and the communication unit respectively.

3. A control circuit of a microwave sensor according to claim 2, characterized in that: The power supply unit includes a first voltage stabilizing filter unit and a second voltage stabilizing filter unit, wherein the first voltage stabilizing filter unit is electrically connected to the control unit, and the second voltage stabilizing filter unit is electrically connected to the antenna unit and the signal amplifying unit respectively.

4. A control circuit of a microwave sensor according to claim 3, characterized in that: The power supply unit further includes a third voltage stabilizing filter unit, the input end of the third voltage stabilizing filter unit is connected to the output end of the second voltage stabilizing filter unit, and the output end of the third voltage stabilizing filter unit is respectively connected to the first amplifier unit and the second amplifier unit.

5. The control circuit of a microwave sensor according to claim 3, characterized in that: The first amplifier includes a first negative feedback circuit, and the second amplifier includes a second negative feedback circuit; the first negative feedback circuit is used to reduce the error of the signal output by the first amplifier, and the second negative feedback circuit is used to reduce the error of the signal output by the second amplifier.

6. The control circuit of a microwave sensor according to claim 1, characterized in that: The control unit further includes a second control unit, the second control unit is electrically connected to the antenna unit, and the second control unit is used to control the antenna unit to start or stop working.

7. The control circuit of a microwave sensor according to claim 1, characterized in that: The control unit further includes a signal output unit, and the signal output unit is electrically connected to the communication unit.

8. A microwave sensor, comprising a housing, characterized in that: A PCB board is arranged in the shell, and the control circuit of the microwave sensor as described in any one of claims 1 to 7 is printed on the PCB board. A transmitting antenna disk and a receiving antenna disk are also arranged on the PCB board, and the transmitting antenna disk and the receiving antenna disk are electrically connected to the control circuit of the microwave sensor respectively.

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