A load mismatch monitoring circuit for a radio frequency amplifier and a radio frequency amplifier

Abstract

The present application is applicable to the field of semiconductor microwave integrated circuits, and provides a load mismatch monitoring circuit for a radio frequency amplifier and a radio frequency amplifier. The load mismatch monitoring circuit includes: the first end of the sampling circuit and the second end of the sampling circuit are connected to the front end of the original radio frequency amplifier circuit load, the third end of the sampling circuit is connected to the first end of the voltage amplifier circuit, and the fourth end of the sampling circuit is used to access the gate power supply signal; the second end of the voltage amplifier circuit is connected to the first end of the rectifier circuit, and the third end of the voltage amplifier circuit is used to access the drain power supply signal; the second end of the rectifier circuit is connected to the first end of the voltage integration circuit; the second end of the voltage integration circuit is connected to the first end of the discharge circuit, and the third end of the voltage integration circuit is used to output a monitoring signal, and the output monitoring signal is the basis for the power consumption control of the radio frequency amplifier. The present application can monitor an impedance mismatch and use the load state change during this impedance mismatch to control power consumption.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor microwave integrated circuits, and in particular, relates to a load mismatch monitoring circuit of a radio frequency amplifier and a radio frequency amplifier. Background Art

[0002] In the fields of communication, radar, medical treatment, automobile, military, aerospace, microwave heating, Internet of Things, etc., RF power amplifiers are basically indispensable. Usually, the most important indicators of RF power amplifiers that we pay attention to are efficiency, power, and linearity, but the anti-mismatch of power amplifiers is also an important indicator as a guarantee of product reliability. Normal power amplifiers have a certain anti-mismatch ability. The common parameter is that they will not burn out under 5:1. Under excessive mismatch ratios, the power amplifier has the risk of burning out.

[0003] The RF power amplifier is terminated with a load and normally works in a matching state with small port reflection. If external conditions change, such as load abnormality, temperature change, medium change, switch switching, load modulation, etc., load mismatch will occur. Once the load is mismatched, the output standing wave of the RF power amplifier will increase and enter an abnormal working state. If this mismatch is large and lasts for a period of time, the power amplifier will burn out.

[0004] In another case, load mismatch may also occur when the product enters another normal working state, such as a microwave cigarette lighter, whose built-in amplifier load is the antenna behind it plus tobacco. As the tobacco evaporates during heating, the composition changes, resulting in a change in the dielectric constant, which is ultimately reflected at the output of the amplifier as impedance mismatch (often an increase in load impedance). This impedance mismatch is relatively small and can be controlled within the range that the amplifier can withstand through design, but how to control power consumption through this load state during mismatch needs to be studied urgently. Summary of the invention

[0005] In view of this, the present application provides a load mismatch monitoring circuit of a radio frequency amplifier and a radio frequency amplifier, which can monitor an impedance mismatch and use the load state change when the impedance mismatch occurs to control power consumption.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a load mismatch monitoring circuit of a radio frequency amplifier, wherein the load mismatch monitoring circuit of the radio frequency amplifier comprises: a sampling circuit, a voltage amplification circuit, a rectification circuit, a voltage integration circuit, and a discharge circuit;

[0008] The first end of the sampling circuit and the second end of the sampling circuit are connected to the front end of the load in the original RF amplifier circuit, the third end of the sampling circuit is connected to the first end of the voltage amplifier circuit, and the fourth end of the sampling circuit is used to connect to the gate power supply signal;

[0009] The second end of the voltage amplifier circuit is connected to the first end of the rectifier circuit, and the third end of the voltage amplifier circuit is used to access the drain power supply signal;

[0010] The second end of the rectifier circuit is connected to the first end of the voltage integration circuit;

[0011] The second end of the voltage integration circuit is connected to the first end of the discharge circuit, and the third end of the voltage integration circuit is used to output a monitoring signal, and the output monitoring signal is a basis for controlling the power consumption of the radio frequency amplifier.

[0012] Based on the first aspect, in some embodiments, the sampling circuit includes a first resistor, a second resistor, a first capacitor and a first inductor;

[0013] The first end of the first resistor is respectively connected to the first end of the sampling circuit, the first end of the first capacitor, and the first end of the first inductor; the second end of the first resistor is respectively connected to the first end of the second resistor and the third end of the sampling circuit; the second end of the second resistor is grounded; the second end of the first capacitor is connected to the second end of the sampling circuit; and the second end of the first inductor is connected to the fourth end of the sampling circuit.

[0014] Based on the first aspect, in some embodiments, the sum of the impedance value of the first resistor and the impedance value of the second resistor is greater than the output impedance of the original RF amplification circuit.

[0015] Based on the first aspect, in some embodiments, the voltage amplification circuit includes a common source configuration amplifier, a second inductor, a second capacitor and a third resistor;

[0016] The gate of the common-source configuration amplifier is connected to the third end of the sampling circuit, the drain of the common-source configuration amplifier is respectively connected to the first end of the second inductor and the first end of the second capacitor, and the source of the common-source configuration amplifier is grounded; the second end of the second inductor is connected to the third end of the voltage amplifier circuit; the second end of the second capacitor is respectively connected to the first end of the third resistor and the second end of the voltage amplifier circuit; and the second end of the third resistor is grounded.

[0017] Based on the first aspect, in some embodiments, the rectifier circuit includes a diode; a forward direction of the diode is connected to a first end of the rectifier circuit, and a negative direction of the diode is connected to a second end of the rectifier circuit;

[0018] The diode is used for half-wave rectification and outputs a positive half-cycle signal of an input signal of the rectification circuit.

[0019] Based on the first aspect, in some embodiments, the voltage integration circuit includes a fourth resistor and a third capacitor;

[0020] The first end of the fourth resistor is connected to the first end of the voltage integration circuit, and the second end of the fourth resistor is respectively connected to the second end of the voltage integration circuit, the third end of the voltage integration circuit, and the first end of the third capacitor; the second end of the third capacitor is grounded.

[0021] Based on the first aspect, in some embodiments, the discharge circuit includes a fifth resistor; a first end of the fifth resistor is connected to the first end of the discharge circuit, and a second end of the fifth resistor is grounded;

[0022] The fifth resistor is greater than the fourth resistor.

[0023] Based on the first aspect, in some embodiments, the fifth resistor is greater than the fourth resistor.

[0024] Based on the first aspect, in some embodiments, the load mismatch monitoring circuit is located at the front end of the output load of the original RF amplification circuit to monitor the load change in real time;

[0025] When the load of the RF amplifier circuit is mismatched, the sampling circuit inputs the collected signal into the voltage amplifier circuit for voltage amplification to obtain an AC signal; the rectifier circuit rectifies the amplified AC signal to obtain a positive half-side voltage waveform; the integration circuit integrates the positive half-side voltage waveform to obtain a stable DC voltage value as the output monitoring signal;

[0026] The acquisition signal changes with the voltage amplitude of the RF output signal of the original RF amplifier circuit acquired by the sampling circuit, the output level of the monitoring signal of the load mismatch monitoring circuit changes with the voltage amplitude of the acquisition signal, and the change of the load state of the original RF amplifier circuit corresponds to the change of the output level of the monitoring signal of the load mismatch monitoring circuit;

[0027] The output level is handed over to a power management chip or a control processing chip to change the bias voltage of the RF amplifier or to shut down or restart it.

[0028] A second aspect of the embodiments of the present application provides a radio frequency amplifier, including the load mismatch monitoring circuit of the radio frequency amplifier as described in the first aspect,

[0029] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0030] The embodiment of the present application monitors the changes in the output load of the RF amplifier circuit in real time through a sampling circuit, a voltage amplifier circuit, a rectifier circuit, a voltage integration circuit, and a discharge circuit, so as to achieve the purpose of monitoring impedance mismatch and controlling power consumption by utilizing the load state change caused by such impedance mismatch. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 is a structural schematic diagram of a load mismatch monitoring circuit of a radio frequency amplifier provided in an embodiment of the present application;

[0033] Figure 2 is a circuit structure schematic diagram of a load mismatch monitoring circuit for a radio frequency amplifier provided in an embodiment of the present application;

[0034] Figure 3 is the voltage obtained by the sampling circuit in the load mismatch monitoring circuit of the radio frequency amplifier provided in the embodiment of the present application;

[0035] Figure 4 It is the final output voltage of the load mismatch monitoring circuit of the RF amplifier provided in the embodiment of the present application. DETAILED DESCRIPTION

[0036] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0037] The present invention belongs to semiconductor microwave integrated circuits, and relates to a radio frequency amplifier load mismatch monitoring circuit, which can be used between an amplifier and a load, and is used in scenarios where load mismatch monitoring is required, to provide the system with external load change reminders, power consumption control, power amplifier protection and other functions, and can be used for but not limited to the output of a transmitting module, the input of a receiving module, and the front end of an antenna. This circuit has a small area and is particularly suitable for electronic products with high volume and energy consumption restrictions, such as microwave cigarette lighters, smart wearables, and handheld communication devices. In order to make the purpose, technical solutions and advantages of this application clearer, the load mismatch monitoring circuit of the radio frequency amplifier provided in the embodiment of this application will be described below in conjunction with the accompanying drawings.

[0038] Figure 1 A schematic diagram of a load mismatch monitoring circuit for a radio frequency amplifier provided in an embodiment of the present application is shown. Figure 1 The load mismatch monitoring circuit 100 of the RF amplifier may include: a sampling circuit 101, a voltage amplifier circuit 102, a rectifier circuit 103, a voltage integration circuit 104, and a discharge circuit 105. The first end of the sampling circuit 101 and the second end of the sampling circuit 101 are connected to the front end of the load in the original RF amplifier circuit 200, the third end of the sampling circuit 101 is connected to the first end of the voltage amplifier circuit 102, and the fourth end of the sampling circuit 101 is used to access the gate power supply signal. The second end of the voltage amplifier circuit 102 is connected to the first end of the rectifier circuit 103, and the third end of the voltage amplifier circuit 102 is used to access the drain power supply signal. The second end of the rectifier circuit 103 is connected to the first end of the voltage integration circuit 104. The second end of the voltage integration circuit 104 is connected to the first end of the discharge circuit 105, and the third end of the voltage integration circuit 104 is used to output a monitoring signal, and the output monitoring signal is the basis for the power consumption control of the RF amplifier.

[0039] Among them, when the load of the original RF amplifier circuit 200 is mismatched, the sampling circuit 101 samples the RF output signal of the original RF amplifier circuit 200 and inputs the sampled signal to the voltage amplifier circuit 102. The voltage amplifier circuit 102 performs voltage amplification on the sampled signal to obtain an AC signal. The rectifier circuit 103 rectifies the amplified AC signal to obtain a positive half-side voltage waveform. The integration circuit integrates the positive half-side voltage waveform to obtain a stable DC voltage value as the output monitoring signal.

[0040] Among them, the acquisition signal changes with the voltage amplitude of the RF output signal of the original RF amplifier circuit 200 acquired by the sampling circuit 101, the output level of the monitoring signal of the load mismatch monitoring circuit 100 changes with the voltage amplitude of the acquisition signal, and the change of the load state of the original RF amplifier circuit 200 corresponds to the change of the output level of the monitoring signal of the load mismatch monitoring circuit 100. The output level changes, that is, the output monitoring signal is used as the basis for the power management chip or the control processing chip to control the bias voltage change or shut down or restart the RF amplifier.

[0041] In some embodiments, see Figure 2 The sampling circuit 101 includes a first resistor R1, a second resistor R2, a first capacitor C1 and a first inductor L1.

[0042] The first end of the first resistor R1 is respectively connected to the first end of the sampling circuit 101, the first end of the first capacitor C1, and the first end of the first inductor L1, and the second end of the first resistor R1 is respectively connected to the first end of the second resistor R2 and the third end of the sampling circuit 101. The second end of the second resistor R2 is grounded; the second end of the first capacitor C1 is connected to the second end of the sampling circuit 101; and the second end of the first inductor L1 is connected to the fourth end of the sampling circuit 101.

[0043] Exemplarily, the sum of the impedance value of the first resistor R1 and the impedance value of the second resistor R2 is greater than the output impedance of the original RF amplifying circuit 200 .

[0044] Exemplarily, the sampling circuit 101 is connected to the output end of the transmitting amplifier to sample the RF output signal. In order to minimize the impact on the original signal, the impedance values ​​of the first resistor R1 and the second resistor R2 are reasonably selected so that the impedance of R1+R2 is much larger than the optimal Loadpull output impedance Zopt of the original RF amplifier, so that the output matching of the amplifier in the original RF amplifier circuit 200 is not affected during sampling; in addition, the impedance ratio of the two resistors R1 and R2 is reasonably selected to achieve circuit multiplexing. While collecting AC signals, the gate bias power supply signal VD1 is divided to provide a gate DC bias voltage for the subsequent voltage amplifier circuit 102.

[0045] Exemplarily, when the original RF amplifier circuit 200 has a bias circuit including a first inductor L1 and a gate power supply at the access point of the sampling circuit 101, the bias circuit can be reused as the gate bias of the voltage amplifier circuit 102; otherwise, a gate power supply VD1 and a first inductor L1 are added to the load mismatch monitoring circuit 100 to provide bias, and a first capacitor C1 is added as a DC blocking capacitor to ensure that this part of the bias circuit does not affect the load.

[0046] In some embodiments, the voltage amplifier circuit 102 includes a common-source amplifier D1 , a second inductor L2 , a second capacitor C2 , and a third resistor R3 .

[0047] The gate of the common source configuration amplifier D1 is connected to the third end of the sampling circuit 101, the drain of the common source configuration amplifier D1 is connected to the first end of the second inductor L2 and the first end of the second capacitor C2 respectively, and the source of the common source configuration amplifier D1 is grounded. The second end of the second inductor L2 is connected to the third end of the voltage amplifier circuit 102. The second end of the second capacitor C2 is connected to the first end of the third resistor R3 and the second end of the voltage amplifier circuit 102 respectively; the second end of the third resistor R3 is grounded.

[0048] Exemplarily, the voltage amplifier circuit 102 is located after the sampling circuit 101, and performs voltage amplification on the dynamic RF output signal obtained by the sampling circuit 101. Since the impedance of the sampling circuit 101 is relatively high, the voltage amplifier circuit 102 in the present invention is implemented by a common source configuration amplifier D1 with high input impedance. The third resistor R3 is the load of the common source configuration amplifier D1, and the tube core is selected to be smaller in size to effectively improve the input impedance; the drain power supply signal VD2 and the second inductor L2 are the drain bias of the common source configuration amplifier D1, and the second capacitor C2 is a DC blocking capacitor to prevent the DC voltage of the drain power supply signal VD2 from entering the lower-level signal. The voltage amplifier circuit 102 amplifies the signal voltage and sends it to the subsequent rectifier circuit 103.

[0049] In some embodiments, the rectifier circuit 103 includes a diode D2 .

[0050] The forward direction of the diode D2 is connected to the first end of the rectifier circuit 103 , and the negative direction of the diode D2 is connected to the second end of the rectifier circuit 103 .

[0051] The diode D2 is used for half-wave rectification and outputs a positive half-cycle signal of the input signal of the rectification circuit 103 .

[0052] The RF sampling signal is a signal with both positive and negative directions. The rectifier circuit 103 rectifies the AC signal amplified by the voltage amplifier circuit 102 to obtain a positive half-waveform. The rectifier diode D2 is a Schottky diode D2 with low voltage drop and high frequency.

[0053] In some embodiments, the voltage integration circuit 104 includes a fourth resistor R4 and a third capacitor C3.

[0054] The first end of the fourth resistor R4 is connected to the first end of the voltage integration circuit 104, and the second end of the fourth resistor R4 is respectively connected to the second end of the voltage integration circuit 104, the third end of the voltage integration circuit 104, and the first end of the third capacitor C3; the second end of the third capacitor C3 is grounded.

[0055] Exemplarily, the integration circuit integrates the positive half-cycle signal to obtain a stable effective voltage amplitude value of the positive half-cycle signal, which is a DC voltage in the voltage range of 0 to VD2. Select appropriate values ​​of the fourth resistor R4 and the third capacitor C3 so that their RC time constant (τ=R*C) is close to the frequency of the monitoring signal, and a stable DC voltage value is obtained as a monitoring signal, which is output to the outside world and can be used by a power management chip or a control processing chip. The output monitoring signal is given to the controller or the power management chip, and compared with the preset voltage value. When the voltage tolerance is exceeded, subsequent processing such as changing, shutting down, and restarting the amplifier bias voltage VD1 in the original RF amplifier circuit 200 is performed.

[0056] In some embodiments, the discharge circuit 105 includes a fifth resistor R5 .

[0057] A first end of the fifth resistor R5 is connected to the first end of the discharge circuit 105 , and a second end of the fifth resistor R5 is grounded.

[0058] Exemplarily, the fifth resistor R5 is greater than the fourth resistor R4.

[0059] Exemplarily, the discharge circuit 105 is provided after the integration circuit, and uses a fifth resistor R5 to provide a discharge loop for the third capacitor C3 in the integration circuit to perform slow discharge so that its voltage can follow the changes of the sampling circuit 101 .

[0060] In some embodiments, the load mismatch monitoring circuit 100 is located at the front end of the output load of the original RF amplifying circuit 200 to monitor the load changes in real time.

[0061] When the load of the original RF amplifier circuit 200 is mismatched, the sampling circuit 101 inputs the collected signal to the voltage amplifier circuit 102 for voltage amplification to obtain an AC signal; the rectifier circuit 103 rectifies the amplified AC signal to obtain a positive half-side voltage waveform; the integration circuit integrates the positive half-side voltage waveform to obtain a stable DC voltage value as the output monitoring signal.

[0062] The acquisition signal changes with the voltage amplitude of the RF output signal of the original RF amplifier circuit 200 acquired by the sampling circuit 101, and the output level of the monitoring signal of the load mismatch monitoring circuit 100 changes with the voltage amplitude of the acquisition signal. The change of the load state of the original RF amplifier circuit 200 corresponds to the change of the output level of the monitoring signal of the load mismatch monitoring circuit 100.

[0063] The output level is handed over to the power management chip or the control processing chip to change the bias voltage of the RF amplifier or to shut down or restart it.

[0064] An embodiment of the present application further provides a radio frequency amplifier, including a load mismatch monitoring circuit 100 of the radio frequency amplifier as in any of the above embodiments.

[0065] For example, the present application embodiment simulates the mismatch monitoring circuit of the RF amplifier load, and the simulation results are as follows: Figure 3 and Figure 4 shown. Figure 3 is the voltage obtained by the sampling circuit 101 in the RF amplifier load mismatch monitoring circuit 100, Figure 4 is the final output voltage of the RF amplifier load mismatch monitoring circuit 100 .

[0066] It can be seen that the RF amplifier load mismatch monitoring circuit proposed in the present invention can monitor impedance mismatch through the sampling circuit 101, the voltage amplification circuit 102, the rectifier circuit 103, the voltage integration circuit 104 and the discharge circuit 105, and select a suitable resistor impedance ratio and the common source configuration amplifier D1, and use the load state change when the impedance mismatch occurs to control power consumption; this makes the mismatch monitoring circuit have a wide range of applications and can be applied to the output end of most RF amplifiers.

[0067] Compared with the existing RF coupler solutions, this solution has a simple structure, no large-area microstrip, and only uses small-area resistors, capacitors and active devices. The circuit occupies a small area, is not affected by frequency, and the solution is simple to implement. It can be designed as an independent chip to achieve area and cost optimization.

[0068] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A load mismatch monitoring circuit for a radio frequency amplifier, characterized in that: include: Sampling circuit, voltage amplifier circuit, rectifier circuit, voltage integration circuit, discharge circuit; The first end of the sampling circuit and the second end of the sampling circuit are connected to the front end of the load in the original RF amplifier circuit, the third end of the sampling circuit is connected to the first end of the voltage amplifier circuit, and the fourth end of the sampling circuit is used to connect to the gate power supply signal; The second end of the voltage amplifier circuit is connected to the first end of the rectifier circuit, and the third end of the voltage amplifier circuit is used to access the drain power supply signal; The second end of the rectifier circuit is connected to the first end of the voltage integration circuit; The second end of the voltage integration circuit is connected to the first end of the discharge circuit, and the third end of the voltage integration circuit is used to output a monitoring signal, and the output monitoring signal is a basis for controlling the power consumption of the radio frequency amplifier.

2. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 1, characterized in that: The sampling circuit includes a first resistor, a second resistor, a first capacitor and a first inductor; The first end of the first resistor is respectively connected to the first end of the sampling circuit, the first end of the first capacitor, and the first end of the first inductor; the second end of the first resistor is respectively connected to the first end of the second resistor and the third end of the sampling circuit; the second end of the second resistor is grounded; the second end of the first capacitor is connected to the second end of the sampling circuit; and the second end of the first inductor is connected to the fourth end of the sampling circuit.

3. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 2, characterized in that: The sum of the impedance value of the first resistor and the impedance value of the second resistor is greater than the output impedance of the original radio frequency amplification circuit.

4. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 1, characterized in that: The voltage amplification circuit includes a common source configuration amplifier, a second inductor, a second capacitor and a third resistor; The gate of the common-source configuration amplifier is connected to the third end of the sampling circuit, the drain of the common-source configuration amplifier is respectively connected to the first end of the second inductor and the first end of the second capacitor, and the source of the common-source configuration amplifier is grounded; the second end of the second inductor is connected to the third end of the voltage amplifier circuit; the second end of the second capacitor is respectively connected to the first end of the third resistor and the second end of the voltage amplifier circuit; and the second end of the third resistor is grounded.

5. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 1, characterized in that: The rectifier circuit includes a diode; the forward direction of the diode is connected to the first end of the rectifier circuit, and the negative direction of the diode is connected to the second end of the rectifier circuit; The diode is used for half-wave rectification and outputs a positive half-cycle signal of an input signal of the rectification circuit.

6. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 1, characterized in that: The voltage integration circuit includes a fourth resistor and a third capacitor; The first end of the fourth resistor is connected to the first end of the voltage integration circuit, and the second end of the fourth resistor is respectively connected to the second end of the voltage integration circuit, the third end of the voltage integration circuit, and the first end of the third capacitor; the second end of the third capacitor is grounded.

7. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 6, characterized in that: The discharge circuit includes a fifth resistor; a first end of the fifth resistor is connected to the first end of the discharge circuit, and a second end of the fifth resistor is grounded.

8. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 7, characterized in that: The fifth resistor is greater than the fourth resistor.

9. The load mismatch monitoring circuit of the radio frequency amplifier according to claim 6, characterized in that: The load mismatch monitoring circuit is located at the front end of the output load of the original RF amplifying circuit to monitor the load changes in real time; When the load of the RF amplifier circuit is mismatched, the sampling circuit inputs the collected signal into the voltage amplifier circuit for voltage amplification to obtain an AC signal; the rectifier circuit rectifies the amplified AC signal to obtain a positive half voltage waveform; The integration circuit integrates the positive half voltage waveform to obtain a stable DC voltage value as an output monitoring signal; The acquisition signal changes with the voltage amplitude of the RF output signal of the original RF amplifier circuit acquired by the sampling circuit, the output level of the monitoring signal of the load mismatch monitoring circuit changes with the voltage amplitude of the acquisition signal, and the change of the load state of the original RF amplifier circuit corresponds to the change of the output level of the monitoring signal of the load mismatch monitoring circuit; The output level is handed over to a power management chip or a control processing chip to change the bias voltage of the RF amplifier or to shut down or restart it.

10. A radio frequency amplifier, characterized in that: A load mismatch monitoring circuit comprising a radio frequency amplifier as described in any one of claims 1 to 9.

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