Power detection circuit

Abstract

The invention provides a power detection circuit. The power detection circuit comprises a first triode, a low-pass circuit, a voltage division circuit, a first resistor, a first radio frequency rectification circuit, a second radio frequency rectification circuit and a third radio frequency rectification circuit, the low-pass circuit is used for filtering high-frequency interference; the voltage division circuit is used for reducing a voltage signal output by the emitting electrode of the first triode in proportion; the first radio frequency rectification circuit, the second radio frequency rectification circuit and the third radio frequency rectification circuit are used for converting alternating current into one-way pulsating direct current. According to the power detection circuit, the power dynamic range of the power detection circuit can be expanded, and the linearity is better.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a power detection circuit. Background Technology

[0002] With the continuous development of Wi-Fi technology, Wi-Fi 7 is becoming increasingly popular, which in turn places higher demands on the power accuracy of Wi-Fi communication systems. In Wi-Fi product applications, power calibration uses the Voltage Detection and Estimation (VDET) method, which converts the radio frequency signal into a DC voltage signal and then feeds it back to the system. The system controls the power amplifier to emit the corresponding power signal by detecting the magnitude of the voltage.

[0003] In addition, the system detects the corresponding voltage value at each power point and then stores a set of voltage vs (voltage-current) power data in the system. Therefore, when calibrating the power, the system expects that the voltage corresponding to each power point should have a certain difference, and the difference should not be too large or too small, commonly known as linearity.

[0004] Related technologies such as power detection circuits Figure 1 As shown, the radio frequency signal is coupled to the input transistor Q through the DC blocking capacitor C1. The short junction between the collector and base of transistor Q forms a diode function for rectifying the radio frequency signal. The bias resistor R1 controls the bias of the transistor Q, which has a diode function. The capacitor C2, resistor R2, and resistor R3 form a low-pass load network to input the reference radio frequency detection voltage. Resistors R2 and R3 form a voltage divider structure, and the ratio of resistors R2 and R3 affects the output magnitude of the detection voltage.

[0005] like Figure 2 As shown, the horizontal axis represents the power of the radio frequency signal, and the vertical axis represents the output voltage after rectification. Although the power detection circuit in related technologies can achieve power accuracy, from... Figure 2 It can be seen that the output voltage curve in the power range of 5~30dBm exhibits an exponential shape, while the voltage remains almost constant in the power range of -20~5dBm. Therefore, the power detection circuits in related technologies not only have a small power dynamic range but also poor linearity, making them difficult to apply in Wi-Fi detection systems. Summary of the Invention

[0006] To address the shortcomings of the aforementioned related technologies, this invention proposes a novel power detection circuit to solve the problems of small power dynamic range and poor linearity in the power detection circuits of the related technologies.

[0007] To solve the above-mentioned technical problems, the present invention provides a power detection circuit, which includes a first transistor, a low-pass circuit, a voltage divider circuit, a first resistor, a first radio frequency rectifier circuit, a second radio frequency rectifier circuit, and a third radio frequency rectifier circuit. The collector of the first transistor is used to connect to the power supply voltage; The input terminal of the low-pass circuit is connected to the emitter of the first transistor, and the output terminal of the low-pass circuit is grounded to filter out high-frequency interference. The input terminal of the voltage divider circuit is connected to the input terminal of the low-pass circuit, and the output terminal of the voltage divider circuit is used to output a detection voltage to proportionally reduce the voltage signal output by the emitter of the first transistor. The first end of the first resistor is used to connect to the power supply voltage, and the second end of the first resistor is connected to the base of the first transistor; The first input terminal of the first RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the first RF rectifier circuit is used to connect to the RF signal, and the output terminal of the first RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power. The first input terminal of the second RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the second RF rectifier circuit is used to connect to the RF signal, and the output terminal of the second RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power. The first input terminal of the third RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the third RF rectifier circuit is used to connect to the RF signal, and the output terminal of the third RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power.

[0008] Preferably, the power detection circuit further includes a first capacitor, the first terminal of which is connected to the collector of the first transistor, and the second terminal of which is grounded.

[0009] Preferably, the low-pass circuit includes a second resistor and a second capacitor; the first end of the second resistor and the first end of the second capacitor are connected and together serve as the input terminal of the low-pass circuit, and the second end of the second resistor and the second end of the second capacitor are connected and together serve as the output terminal of the low-pass circuit.

[0010] Preferably, the voltage divider circuit includes a third resistor and a fourth resistor; the first end of the third resistor serves as the input terminal of the voltage divider circuit, the second end of the third resistor serves as the output terminal of the voltage divider circuit, the first end of the fourth resistor is connected to the second end of the third resistor, and the second end of the fourth resistor is grounded.

[0011] Preferably, the first radio frequency rectifier circuit includes a second transistor, a fifth resistor, a third capacitor, a third transistor, a sixth resistor, a seventh resistor, and a fourth capacitor; The collector of the second transistor serves as the output terminal of the first radio frequency rectifier circuit, and the emitter of the second transistor is grounded. The first end of the fifth resistor is connected to the first end of the first resistor and serves as the first input terminal of the first radio frequency rectifier circuit. The first terminal of the third capacitor serves as the second input terminal of the first radio frequency rectifier circuit. The collector of the third transistor is connected to the second terminal of the fifth resistor and the second terminal of the third capacitor, respectively, and the emitter of the third transistor is grounded. The two ends of the sixth resistor are respectively connected to the collector of the third transistor and the base of the third transistor; The two ends of the seventh resistor are respectively connected to the base of the third transistor and the base of the second transistor; The first terminal of the fourth capacitor is connected to the base of the second transistor, and the second terminal of the fourth capacitor is grounded.

[0012] Preferably, the second RF rectifier circuit includes a fourth transistor, an eighth resistor, a fifth capacitor, a fifth transistor, a ninth resistor, a tenth resistor, and a sixth capacitor. The collector of the fourth transistor is connected to the collector of the second transistor and serves as the output terminal of the second RF rectifier circuit; the emitter of the fourth transistor is grounded. The first end of the eighth resistor is connected to the first end of the fifth resistor and serves as the first input terminal of the second RF rectifier circuit. The first terminal of the fifth capacitor serves as the second input terminal of the second radio frequency rectifier circuit. The collector of the fifth transistor is connected to the second terminal of the eighth resistor and the second terminal of the fifth capacitor, respectively, and the emitter of the fifth transistor is grounded. The two ends of the ninth resistor are respectively connected to the collector of the fifth transistor and the base of the fifth transistor; The two ends of the tenth resistor are respectively connected to the base of the fifth transistor and the base of the fourth transistor; The first terminal of the sixth capacitor is connected to the base of the fourth transistor, and the second terminal of the sixth capacitor is grounded.

[0013] Preferably, the third radio frequency rectifier circuit includes a sixth transistor, an eleventh resistor, a seventh capacitor, a seventh transistor, a twelfth resistor, a thirteenth resistor, and an eighth capacitor. The collector of the sixth transistor is connected to the collector of the fourth transistor and serves as the output terminal of the third RF rectifier circuit; the emitter of the fourth transistor is grounded. The first end of the eleventh resistor is connected to the first end of the eighth resistor and serves as the first input terminal of the third radio frequency rectifier circuit. The first terminal of the seventh capacitor is connected to the second terminal of the fifth capacitor and serves as the second input terminal of the third radio frequency rectifier circuit. The collector of the seventh transistor is connected to the second terminal of the eleventh resistor and the second terminal of the seventh capacitor, respectively, and the emitter of the seventh transistor is grounded. The two ends of the twelfth resistor are respectively connected to the collector of the seventh transistor and the base of the seventh transistor; The two ends of the thirteenth resistor are respectively connected to the base of the seventh transistor and the base of the sixth transistor; The first terminal of the eighth capacitor is connected to the base of the sixth transistor, and the second terminal of the eighth capacitor is grounded.

[0014] Compared with related technologies, the power detection circuit in this invention improves the power dynamic range and linearity by adding a first RF rectifier circuit, a second RF rectifier circuit, and a third RF rectifier circuit for converting AC power into unidirectional pulsating DC power, and by connecting the first resistor only to the base of the first transistor. Attached Figure Description

[0015] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings: Figure 1 Circuit diagram of a power detection circuit provided for related technologies; Figure 2 A graph showing the relationship between the output voltage and power of a power detection circuit provided for related technologies; Figure 3 A circuit diagram of a power detection circuit provided in an embodiment of the present invention; Figure 4 The diagram shows the relationship between the detection voltage and power of the power detection circuit provided in the embodiment of the present invention. Detailed Implementation

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0017] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a power detection circuit 100, combined with... Figure 3 As shown, it includes a first transistor Q1, a low-pass circuit 1, a voltage divider circuit 2, a first resistor R1, a first radio frequency rectifier circuit 3, a second radio frequency rectifier circuit 4, and a third radio frequency rectifier circuit 5. In this circuit, the collector of the first transistor Q1 is connected to the supply voltage VDD; the first transistor Q1 acts as an emitter follower, and the voltage received at the base is output from the emitter.

[0020] The input terminal of the low-pass circuit 1 is connected to the emitter of the first transistor Q1, and the output terminal of the low-pass circuit 1 is grounded to filter out high-frequency interference. In this embodiment, the low-pass circuit 1 includes a second resistor R2 and a second capacitor C2; the first terminal of the second resistor R2 and the first terminal of the second capacitor C2 are connected and together serve as the input terminal of the low-pass circuit 1, and the second terminal of the second resistor R2 and the second terminal of the second capacitor C2 are connected and together serve as the output terminal of the low-pass circuit 1.

[0021] The input terminal of voltage divider circuit 2 is connected to the input terminal of low-pass circuit 1. The output terminal of voltage divider circuit 2 is used to output a detection voltage VDET, which is used to proportionally reduce the voltage signal output from the emitter of the first transistor Q1 by the required voltage, directly affecting the magnitude of the voltage output from the emitter of the first transistor Q1. In this embodiment, voltage divider circuit 2 includes a third resistor R3 and a fourth resistor R4; the first terminal of the third resistor R3 serves as the input terminal of voltage divider circuit 2, the second terminal of the third resistor R3 serves as the output terminal of voltage divider circuit 2, the first terminal of the fourth resistor R4 is connected to the second terminal of the third resistor R3, and the second terminal of the fourth resistor R4 is grounded.

[0022] The first terminal of the first resistor R1 is connected to the supply voltage VDD, and the second terminal of the first resistor R1 is connected to the base of the first transistor Q1. The first resistor R1 is used to adjust the voltage of the first transistor Q1.

[0023] The first input terminal of the first RF rectifier circuit 3 is used to connect to the power supply voltage VDD, the second input terminal of the first RF rectifier circuit 3 is used to connect to the RF signal, and the output terminal of the first RF rectifier circuit 3 is connected to the base of the first transistor Q1 to convert AC power into unidirectional pulsating DC power.

[0024] In this embodiment, the first radio frequency rectifier circuit 3 includes a second transistor Q2, a fifth resistor R5, a third capacitor C3, a third transistor Q3, a sixth resistor R6, a seventh resistor R7, and a fourth capacitor C4.

[0025] The collector of the second transistor Q2 serves as the output terminal of the first radio frequency rectifier circuit 3, and the emitter of the second transistor Q2 is grounded. This is used to amplify the DC signal rectified by the third transistor Q3 and output it to the base of the first transistor Q1.

[0026] The first end of the fifth resistor R5 is connected to the first end of the first resistor R1 and serves as the first input terminal of the first RF rectifier circuit 3, acting as a bias resistor.

[0027] The first terminal of the third capacitor C3 serves as the second input terminal of the first RF rectifier circuit 3, acting as a coupling and DC blocking capacitor.

[0028] The collector of the third transistor Q3 is connected to the second terminal of the fifth resistor R5 and the second terminal of the third capacitor C3, respectively, and the emitter of the third transistor Q3 is grounded.

[0029] The two ends of the sixth resistor R6 are connected to the collector and the base of the third transistor Q3, respectively, serving as the diode voltage regulator and rectifier resistor formed by the third transistor Q3.

[0030] The two ends of the seventh resistor R7 are connected to the base of the third transistor Q3 and the base of the second transistor Q2, respectively.

[0031] The first terminal of the fourth capacitor C4 is connected to the base of the second transistor Q2, and the second terminal of the fourth capacitor C4 is grounded. Together with the seventh resistor R7, they form an RC filter circuit.

[0032] The first input terminal of the second RF rectifier circuit 4 is used to connect to the power supply voltage VDD, the second input terminal of the second RF rectifier circuit 4 is used to connect to the RF signal, and the output terminal of the second RF rectifier circuit 4 is connected to the base of the first transistor Q1 to convert AC power into unidirectional pulsating DC power.

[0033] In this embodiment, the second RF rectifier circuit 4 includes a fourth transistor Q4, an eighth resistor R8, a fifth capacitor C5, a fifth transistor Q5, a ninth resistor R9, a tenth resistor R10, and a sixth capacitor C6.

[0034] The collector of the fourth transistor Q4 is connected to the collector of the second transistor Q2 and serves as the output terminal of the second RF rectifier circuit 4. The emitter of the fourth transistor Q4 is grounded and is used to amplify the DC signal rectified by the fifth transistor Q5 and output it to the base of the first transistor Q1.

[0035] The first end of the eighth resistor R8 is connected to the first end of the fifth resistor R5 and serves as the first input terminal of the second RF rectifier circuit 4, acting as a bias resistor.

[0036] The first terminal of the fifth capacitor C5 serves as the second input terminal of the second RF rectifier circuit 4, acting as a coupling and DC blocking capacitor.

[0037] The collector of the fifth transistor Q5 is connected to the second terminal of the eighth resistor R8 and the second terminal of the fifth capacitor C5, respectively, and the emitter of the fifth transistor Q5 is grounded.

[0038] The two ends of the ninth resistor R9 are connected to the collector and the base of the fifth transistor Q5, respectively, serving as the diode voltage regulator and rectifier resistor formed by the fifth transistor Q5.

[0039] The two ends of the tenth resistor R10 are connected to the base of the fifth transistor Q5 and the base of the fourth transistor Q4, respectively.

[0040] The first terminal of the sixth capacitor C6 is connected to the base of the fourth transistor Q4, and the second terminal of the sixth capacitor C6 is grounded. Together with the tenth resistor R10, they form an RC filter circuit.

[0041] The first input terminal of the third RF rectifier circuit 5 is used to connect the power supply voltage VDD, the second input terminal of the third RF rectifier circuit 5 is used to connect the RF signal, and the output terminal of the third RF rectifier circuit 5 is connected to the base of the first transistor Q1 to convert the AC power into unidirectional pulsating DC power.

[0042] In this embodiment, the third RF rectifier circuit 5 includes a sixth transistor Q6, an eleventh resistor R11, a seventh capacitor C7, a seventh transistor Q7, a twelfth resistor R12, a thirteenth resistor R13, and an eighth capacitor C8.

[0043] The collector of the sixth transistor Q6 is connected to the collector of the fourth transistor Q4 and serves as the output terminal of the third RF rectifier circuit 5. The emitter of the fourth transistor Q4 is grounded and used to amplify the DC signal rectified by the seventh transistor Q7 and output it to the base of the first transistor Q1.

[0044] The first end of the eleventh resistor R11 is connected to the first end of the eighth resistor R8 and serves as the first input terminal of the third RF rectifier circuit 5, acting as a bias resistor.

[0045] The first end of the seventh capacitor C7 is connected to the second end of the fifth capacitor C5 and serves as the second input terminal of the third RF rectifier circuit 5, acting as a coupling and DC blocking capacitor.

[0046] The collector of the seventh transistor Q7 is connected to the second terminal of the eleventh resistor R11 and the second terminal of the seventh capacitor C7, respectively, and the emitter of the seventh transistor Q7 is grounded.

[0047] The two ends of the twelfth resistor R12 are connected to the collector and the base of the seventh transistor Q7, respectively, serving as the diode voltage regulator and rectifier resistor formed by the seventh transistor Q7.

[0048] The two ends of the thirteenth resistor R13 are connected to the base of the seventh transistor Q7 and the base of the sixth transistor Q6, respectively.

[0049] The first terminal of the eighth capacitor C8 is connected to the base of the fourth transistor Q4, and the second terminal of the eighth capacitor C8 is grounded. Together with the thirteenth resistor R13, they form an RC filter circuit.

[0050] The first RF rectifier circuit 3, the second RF rectifier circuit 4, and the third RF rectifier circuit 5 are respectively used to convert the AC power of high-power signals, medium-power signals, and low-power signals into unidirectional pulsating DC power, so as to integrate them into a single output for mutual compensation, thereby ensuring that high-power signals, medium-power signals, and low-power signals all have good linearity.

[0051] In addition, the power detection circuit 100 of this embodiment also includes a first capacitor C1. The first terminal of the first capacitor C1 is connected to the collector of the first transistor Q1, and the second terminal of the first capacitor C1 is grounded. This is equivalent to connecting the first terminal of the first capacitor C1, the first terminal of the first resistor R1, and the collector of the first transistor Q1 to the power supply voltage VDD. The first capacitor C1 is used for filtering.

[0052] like Figure 4As shown, the power dynamic range of the power detection circuit 100 in this embodiment is between -20dBm and 20dBm, and its overall linearity is good, especially in the power range of -10 to 20dBm, where it is basically completely linear.

[0053] Compared with related technologies, the power detection circuit 100 in this invention improves the power dynamic range and linearity by adding a first radio frequency rectifier circuit 3, a second radio frequency rectifier circuit 4, and a third radio frequency rectifier circuit 5 for converting AC power into unidirectional pulsating DC power, and by connecting the first resistor R1 only to the base of the first transistor Q1.

[0054] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A power detection circuit, characterized in that, The power detection circuit includes a first transistor, a low-pass circuit, a voltage divider circuit, a first resistor, a first RF rectifier circuit, a second RF rectifier circuit, and a third RF rectifier circuit. The collector of the first transistor is used to connect to the power supply voltage; The input terminal of the low-pass circuit is connected to the emitter of the first transistor, and the output terminal of the low-pass circuit is grounded to filter out high-frequency interference. The input terminal of the voltage divider circuit is connected to the input terminal of the low-pass circuit, and the output terminal of the voltage divider circuit is used to output a detection voltage to proportionally reduce the voltage signal output by the emitter of the first transistor. The first end of the first resistor is used to connect to the power supply voltage, and the second end of the first resistor is connected to the base of the first transistor; The first input terminal of the first RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the first RF rectifier circuit is used to connect to the RF signal, and the output terminal of the first RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power. The first input terminal of the second RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the second RF rectifier circuit is used to connect to the RF signal, and the output terminal of the second RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power. The first input terminal of the third RF rectifier circuit is used to connect to the power supply voltage, the second input terminal of the third RF rectifier circuit is used to connect to the RF signal, and the output terminal of the third RF rectifier circuit is connected to the base of the first transistor to convert AC power into unidirectional pulsating DC power.

2. The power detection circuit as described in claim 1, characterized in that, The power detection circuit further includes a first capacitor, the first end of which is connected to the collector of the first transistor, and the second end of which is grounded.

3. The power detection circuit as described in claim 1, characterized in that, The low-pass circuit includes a second resistor and a second capacitor; the first end of the second resistor and the first end of the second capacitor are connected and together serve as the input terminal of the low-pass circuit, and the second end of the second resistor and the second end of the second capacitor are connected and together serve as the output terminal of the low-pass circuit.

4. The power detection circuit as described in claim 3, characterized in that, The voltage divider circuit includes a third resistor and a fourth resistor; the first end of the third resistor serves as the input terminal of the voltage divider circuit, the second end of the third resistor serves as the output terminal of the voltage divider circuit, the first end of the fourth resistor is connected to the second end of the third resistor, and the second end of the fourth resistor is grounded.

5. The power detection circuit as described in claim 1, characterized in that, The first radio frequency rectifier circuit includes a second transistor, a fifth resistor, a third capacitor, a third transistor, a sixth resistor, a seventh resistor, and a fourth capacitor; The collector of the second transistor serves as the output terminal of the first radio frequency rectifier circuit, and the emitter of the second transistor is grounded. The first end of the fifth resistor is connected to the first end of the first resistor and serves as the first input terminal of the first radio frequency rectifier circuit. The first terminal of the third capacitor serves as the second input terminal of the first radio frequency rectifier circuit. The collector of the third transistor is connected to the second terminal of the fifth resistor and the second terminal of the third capacitor, respectively, and the emitter of the third transistor is grounded. The two ends of the sixth resistor are respectively connected to the collector of the third transistor and the base of the third transistor; The two ends of the seventh resistor are respectively connected to the base of the third transistor and the base of the second transistor; The first terminal of the fourth capacitor is connected to the base of the second transistor, and the second terminal of the fourth capacitor is grounded.

6. The power detection circuit as described in claim 5, characterized in that, The second RF rectifier circuit includes a fourth transistor, an eighth resistor, a fifth capacitor, a fifth transistor, a ninth resistor, a tenth resistor, and a sixth capacitor; The collector of the fourth transistor is connected to the collector of the second transistor and serves as the output terminal of the second RF rectifier circuit; the emitter of the fourth transistor is grounded. The first end of the eighth resistor is connected to the first end of the fifth resistor and serves as the first input terminal of the second RF rectifier circuit. The first terminal of the fifth capacitor serves as the second input terminal of the second radio frequency rectifier circuit. The collector of the fifth transistor is connected to the second terminal of the eighth resistor and the second terminal of the fifth capacitor, respectively, and the emitter of the fifth transistor is grounded. The two ends of the ninth resistor are respectively connected to the collector of the fifth transistor and the base of the fifth transistor; The two ends of the tenth resistor are respectively connected to the base of the fifth transistor and the base of the fourth transistor; The first terminal of the sixth capacitor is connected to the base of the fourth transistor, and the second terminal of the sixth capacitor is grounded.

7. The power detection circuit as described in claim 6, characterized in that, The third radio frequency rectifier circuit includes a sixth transistor, an eleventh resistor, a seventh capacitor, a seventh transistor, a twelfth resistor, a thirteenth resistor, and an eighth capacitor. The collector of the sixth transistor is connected to the collector of the fourth transistor and serves as the output terminal of the third RF rectifier circuit; the emitter of the fourth transistor is grounded. The first end of the eleventh resistor is connected to the first end of the eighth resistor and serves as the first input terminal of the third radio frequency rectifier circuit. The first terminal of the seventh capacitor is connected to the second terminal of the fifth capacitor and serves as the second input terminal of the third radio frequency rectifier circuit. The collector of the seventh transistor is connected to the second terminal of the eleventh resistor and the second terminal of the seventh capacitor, respectively, and the emitter of the seventh transistor is grounded. The two ends of the twelfth resistor are respectively connected to the collector of the seventh transistor and the base of the seventh transistor; The two ends of the thirteenth resistor are respectively connected to the base of the seventh transistor and the base of the sixth transistor; The first terminal of the eighth capacitor is connected to the base of the sixth transistor, and the second terminal of the eighth capacitor is grounded.

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