Current self-protection circuit for linear power amplifier

Abstract

The invention discloses a current self-protection circuit for a linear power amplifier, relates to the technical field of Tokamak device diagnosis, and solves the problem that probe data acquisition is affected due to the fact that an existing Tokamak device probe diagnosis circuit stops working of a power amplifier during overcurrent. According to the scheme, a multi-stage amplifier is connected with the input of a class-B power amplifier, the output of the class-B power amplifier is connected with a driving current limiting circuit, and the driving current limiting circuit is connected with a probe; the driving current limiting circuit is connected with the input of the multi-stage amplifier through the feedback circuit, is connected with an NPN transistor of the class B power amplifier through the forward current limiting circuit, and is connected with a PNP transistor of the class B power amplifier through the negative current limiting circuit; the driving current limiting circuit provides two different resistance values; by arranging the feedback loop, when overcurrent occurs in the probe diagnosis circuit, the current is pulled down instead of stopping the power amplifier, and probe data acquisition is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of tokamak device diagnosis, and more particularly to a current autonomous protection circuit for a linear power amplifier. Background Art

[0002] In a fusion tokamak device, the probe is a diagnostic device that is in direct contact with the plasma. It can directly and effectively measure the local plasma parameters in space with high time and space resolution. Therefore, almost all tokamaks are currently using probe diagnosis. At present, the main measurement methods of the probe include three-probe, suspended probe, single probe and double probe. For a single probe, a specific driving voltage is applied between the probe pair and a reference electrode (usually a conductor with a large contact area with the plasma, such as the device wall, etc.), the current on the probe is detected, and a volt-ampere characteristic curve is drawn to infer the parameters of the plasma. For a double probe, it is a probe combination composed of two probes in an overall suspended state. A voltage of arbitrary waveform is applied between the two probes. The current of the two probes can also be detected, and a double probe volt-ampere characteristic curve can be drawn to obtain the corresponding electron temperature and electron density. Due to the complexity of plasma behavior, multiple edge localized modes (ELMs) may erupt under the conditions of plasma high confinement mode discharge, and large currents may appear at the probe end. These currents may be several times higher than the rated current of the power amplifier that provides voltage for it. On the one hand, these transient currents will cause the power amplifier to overcurrent, exceeding the device tolerance and causing device loss. On the other hand, they may also cause the probe to burn out.

[0003] At present, in probe diagnosis, the commonly used strategy is to stop the power amplifier output after overcurrent occurs and no longer be put into use in this plasma discharge; or to shut down the protection for a period of time and then resume working until the discharge ends. Both of the above processing methods will affect the acquisition of probe data. Summary of the invention

[0004] The purpose of the present application is to provide a current autonomous protection circuit for a linear power amplifier, so as to solve the problem that when an overcurrent occurs in the probe diagnostic circuit of the existing tokamak device, the power amplifier stops working, affecting the probe's acquisition of data. By setting up a current autonomous protection circuit for the linear power amplifier, when an overcurrent occurs in the probe diagnostic circuit, the power amplifier is not directly shut down, but the current is lowered, and the work is continued after the current returns to normal, thereby fully ensuring the integrity of the probe diagnostic data.

[0005] The above-mentioned technical purpose of the present application is achieved through the following technical scheme: including: a multi-stage amplifier, a class B power amplifier, a forward current limiting circuit, a negative current limiting circuit, a driving current limiting circuit, a feedback circuit and a probe; the multi-stage amplifier is connected to the input of the class B power amplifier, the output of the class B power amplifier is connected to the driving current limiting circuit, and the driving current limiting circuit is connected to the probe; the driving current limiting circuit is connected to the input of the multi-stage amplifier through the feedback circuit, the driving current limiting circuit is connected to the NPN transistor of the class B power amplifier through the forward current limiting circuit, and the driving current limiting circuit is connected to the PNP transistor of the class B power amplifier through the negative current limiting circuit; wherein, the driving current limiting circuit is used to provide two different resistance values.

[0006] By adopting the above technical scheme, a feedback loop consisting of a driving current limiting circuit, a positive current limiting circuit, and a negative current limiting circuit is set up to coordinate with adjusting the output current of the Class B power amplifier, thereby realizing autonomous protection of the probe diagnostic circuit from overcurrent conditions. The method of lowering the output current of the power amplifier is used instead of the traditional method of stopping the power amplifier, thereby ensuring that the output is not shut down and the probe continuously collects diagnostic data.

[0007] In a possible implementation, the driving current limiting circuit includes: a resistor R1, a resistor R2 and a switch K1, wherein one end of the resistor R1 is connected to the output of the class B power amplifier, and the other end is connected to the probe through the resistor R2, and the resistor R2 is connected in parallel with the switch K1.

[0008] In a possible implementation, when the probe is in a first current environment, the switch K1 is disconnected to provide a resistance value of R1+R2; when the probe is in a second current environment, the switch K1 is closed to provide a resistance value of R1.

[0009] In a possible implementation, a current value of the first current environment is smaller than a current value of the second current environment.

[0010] In a possible implementation, the forward current limiting circuit includes: an NPN transistor Q2 and a diode D1, the collector of the NPN transistor Q2 is connected to the base of the NPN transistor of the class B amplifier, the base of the NPN transistor Q2 is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the emitter of the NPN transistor of the class B amplifier, and the emitter of the NPN transistor Q2 is connected to the driving current limiting circuit.

[0011] In one possible implementation, the negative current limiting circuit includes: a PNP transistor Q4 and a diode D2, the collector of the PNP transistor Q4 is connected to the base of the class B amplifier PNP transistor, the base of the PNP transistor Q4 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the emitter of the class B amplifier PNP transistor, and the emitter of the PNP transistor Q4 is connected to the driving current limiting circuit.

[0012] In one possible implementation, the Class B power amplifier includes: an NPN transistor Q1 and a PNP transistor Q2, the bases of the NPN transistor Q1 and the PNP transistor Q2 are connected as the input of the Class B power amplifier, the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected as the output of the Class B power amplifier, the collector of the NPN transistor Q1 is connected to a positive high voltage, and the collector of the PNP transistor Q2 is connected to a negative high voltage.

[0013] In one possible implementation, the multi-stage amplifier includes: a first amplifier and a second amplifier connected in cascade, wherein the first input of the first amplifier is connected to a control signal, the second input is connected to a feedback circuit, the output is connected to the second amplifier, and the output of the second amplifier is connected to the input of a Class B power amplifier.

[0014] In a possible implementation, it also includes: a second amplifier protection loop, one end of the second amplifier protection loop is connected to the output of the class B power amplifier, and the other end is connected to the reference ground of the class B power amplifier, and the second amplifier protection loop is also connected to the reference ground of the second amplifier.

[0015] In a possible implementation, the second amplifier protection circuit includes: a resistor R3 and a capacitor C1, one end of the resistor R3 is connected to the output of the class B power amplifier, and the other end is connected to the reference ground of the second amplifier and the capacitor C1, and the capacitor C1 is connected to the reference ground of the class B power amplifier.

[0016] Compared with the prior art, the present application has the following beneficial effects: the present solution creatively sets up a feedback loop consisting of a driving current limiting circuit, a forward current limiting circuit, and a negative current limiting circuit. When an overcurrent occurs in the probe loop, the driving current limiting circuit divides the voltage, and the positive current limiting circuit and the negative current limiting circuit change the base drive of the two transistors of the Class B power amplifier, thereby lowering the output current of the Class B power amplifier, thereby protecting the probe and the power amplifier from being burned out due to overcurrent in the loop, and ensuring that the power amplifier continues to work. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0018] Figure 1 is a schematic diagram of a current autonomous protection circuit for a linear power amplifier;

[0019] Figure 2 The output voltage and current waveforms of the class B amplifier without the current autonomous protection circuit activated in the low current region;

[0020] Figure 3 The first waveform diagram of the output voltage and current of the class B amplifier of the low current region startup current autonomous protection circuit;

[0021] Figure 4 The second waveform diagram of the output voltage and current of the class B amplifier of the startup current autonomous protection circuit in the low current region;

[0022] Figure 5 The output voltage and current waveforms of the class B amplifier without the current autonomous protection circuit activated in the high current region;

[0023] Figure 6 The first waveform diagram of the output voltage and current of the class B amplifier of the startup current autonomous protection circuit in the large current region;

[0024] Figure 7 The second waveform diagram of the output voltage and current of the Class B amplifier of the startup current autonomous protection circuit in the large current area.

[0025] Marks and corresponding parts names in the attached drawings:

[0026] 1. Forward current limiting circuit; 2. Negative current limiting circuit; 3. Second amplifier protection circuit; 4. Drive current limiting circuit. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0028] See also Figure 1As shown, an embodiment of the present application provides a current autonomous protection circuit for a linear power amplifier, including: a multi-stage amplifier, a class B power amplifier, a forward current limiting circuit 1, a negative current limiting circuit 2, a driving current limiting circuit 4, a feedback circuit and a probe; the multi-stage amplifier is connected to the input of the class B power amplifier, the output of the class B power amplifier is connected to the driving current limiting circuit 4, and the driving current limiting circuit 4 is connected to the probe; the driving current limiting circuit 4 is connected to the input of the multi-stage amplifier through the feedback circuit, the driving current limiting circuit 4 is connected to the NPN transistor of the class B power amplifier through the forward current limiting circuit 1, and the driving current limiting circuit 4 is connected to the PNP transistor of the class B power amplifier through the negative current limiting circuit 2; wherein, the driving current limiting circuit 4 is used to provide two different resistance values.

[0029] Specifically, the current autonomous protection circuit of the present scheme includes: a multi-stage amplifier, a class B power amplifier, a forward current limiting circuit 1, a negative current limiting circuit 2, a driving current limiting circuit 4, a feedback circuit and a probe. Among them, the multi-stage amplifier inputs a smaller input control signal (e.g., within positive and negative 10V) into the class B power amplifier through multi-stage amplification, and the class B power amplifier realizes amplified output through the alternating cooperation of two transistors. The amplified output is applied to the probe through the driving current limiting circuit 4. The probe is directly in contact with the tokamak plasma. By detecting the current on the probe, the volt-ampere characteristic curve is drawn, and then the local plasma parameters of the tokamak plasma are calculated. At the same time, the current autonomous protection circuit sets a dual feedback loop: on the one hand, the input of the multi-stage amplifier is adjusted by sampling the current at the output end of the autonomous protection circuit through the feedback circuit; on the other hand, the output current of the class B power amplifier is adjusted by the cooperation of the driving current limiting circuit 4, the forward current limiting circuit 1, and the negative current limiting circuit 2.

[0030] The principle of autonomous protection in this scheme is that when the probe moves on the surface of the tokamak plasma, the current environment changes. When the probe is placed in a high current environment, in order to avoid the high current burning the probe and the power amplifier, and to ensure the continuous operation of the power amplifier, this scheme creatively sets a feedback loop consisting of a driving current limiting circuit 4, a positive current limiting circuit 1, and a negative current limiting circuit 2. When an overcurrent occurs in the probe loop, the voltage is divided by the driving current limiting circuit 4, and the base drive of the two transistors of the class B power amplifier is changed by the positive current limiting circuit 1 and the negative current limiting circuit 2, thereby lowering the output current of the class B power amplifier. Unlike directly stopping the power amplifier, this scheme protects the probe and the power amplifier from being burned due to the overcurrent of the loop while ensuring the continuous operation of the power amplifier. When the probe overcurrent disappears, the voltage division of the driving current limiting circuit 4 is reduced, and the base drive of the two transistors of the class B power amplifier is changed again by the positive current limiting circuit 1 and the negative current limiting circuit 2, thereby restoring the output current of the class B power amplifier to normal. Unlike directly stopping the power amplifier, this scheme performs autonomous protection based on the current environment contacted by the probe.

[0031] The improvement of this solution is that a feedback loop is set up to autonomously protect the probe diagnostic circuit power supply from overcurrent, so as to lower the power amplifier output current instead of the traditional method of stopping the power amplifier, thereby ensuring that the output is not shut down and the probe continuously collects diagnostic data.

[0032] In one possible implementation, the multi-stage amplifier includes: a first amplifier and a second amplifier connected in cascade, wherein the first input of the first amplifier is connected to a control signal, the second input is connected to a feedback circuit, the output is connected to the second amplifier, and the output of the second amplifier is connected to the input of a Class B power amplifier.

[0033] It should be noted that the multi-stage amplifier is not limited to two stages, and in actual use, a multi-stage amplifier cascade connection can be set as needed. Next, a two-stage amplifier is used for explanation.

[0034] In one possible implementation, the Class B power amplifier includes: an NPN transistor Q1 and a PNP transistor Q2, the bases of the NPN transistor Q1 and the PNP transistor Q2 are connected as the input of the Class B power amplifier, the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected as the output of the Class B power amplifier, the collector of the NPN transistor Q1 is connected to a positive high voltage, and the collector of the PNP transistor Q2 is connected to a negative high voltage.

[0035] It should be noted that the Class B power amplifier includes an NPN transistor Q1 and a PNP transistor Q2. The two transistors work alternately, one working in the positive half cycle of the signal and the other working in the negative half cycle of the signal, and the output forms a complete waveform.

[0036] In a possible implementation, the forward current limiting circuit 1 includes: an NPN transistor Q2 and a diode D1, the collector of the NPN transistor Q2 is connected to the base of the class B amplifier NPN transistor Q1, the base of the NPN transistor Q2 is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the emitter of the class B amplifier NPN transistor, and the emitter of the NPN transistor Q2 is connected to the driving current limiting circuit 4.

[0037] Specifically, the forward current limiting circuit 1 includes an NPN transistor and a diode; the collector of the NPN transistor Q2 of the forward current limiting circuit 1 is connected to the base of the class B amplifier NPN transistor Q1, and is also connected to the output end of the second amplifier; the anode of the diode D1 of the forward current limiting circuit 1 is connected to the emitter of the class B amplifier NPN transistor Q1, and the cathode is connected to the base of the NPN transistor Q2.

[0038] In one possible implementation, the negative current limiting circuit 2 includes: a PNP transistor Q4 and a diode D2, the collector of the PNP transistor Q4 is connected to the base of the class B amplifier PNP transistor, the base of the PNP transistor Q4 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the emitter of the class B amplifier PNP transistor, and the emitter of the PNP transistor Q4 is connected to the driving current limiting circuit 4.

[0039] Specifically, the negative current limiting circuit 2 includes a PNP transistor and a diode; the collector of the PNP transistor Q4 of the negative current limiting circuit 2 is connected to the base of the class B amplifier PNP transistor Q3, and is also connected to the output end of the second amplifier; the cathode of the diode D2 of the negative current limiting circuit 2 is connected to the emitter of the class B amplifier PNP transistor Q3, and the anode is connected to the base of the PNP transistor Q4.

[0040] It should be noted that the emitter of the NPN transistor Q2 of the forward current limiting circuit 1 is connected to the emitter of the PNP transistor Q4 of the negative current limiting circuit 2, which is defined as point O; point O is connected to the output point B of the driving current limiting circuit 4.

[0041] In a possible implementation, the driving current limiting circuit 4 includes: a resistor R1, a resistor R2 and a switch K1, one end of the resistor R1 is connected to the output of the class B power amplifier, and the other end is connected to the probe through the resistor R2, and the resistor R2 is connected in parallel with the switch K1. Further, when the probe is in a first current environment, the switch K1 is disconnected to provide a resistance value of R1+R2; when the probe is in a second current environment, the switch K1 is closed to provide a resistance value of R1. Further, the current value of the first current environment is less than the current value of the second current environment.

[0042] Specifically, the driving current limiting circuit 4 includes a resistor R1, a resistor R2 and a switch K1 connected in parallel at both ends of the resistor R2. The output of the class B power amplifier is taken as point A, one end of the resistor R1 is connected to point A, and the other end is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the emitter of the negative current limiting circuit 2PNP transistor Q4; the driving current limiting circuit 4 uses resistors R1 and R2 in series, wherein the resistor R2 is much larger than the resistor R1, and the current environment in which the probe is placed is different due to the different contact positions on the tokamak plasma. Therefore, in order to improve the signal-to-noise ratio, different resistance values ​​are used for the current environment of the probe at different positions.

[0043] When the probe is in a relatively small first current environment: the switch K1 is separated, the resistors R1 and R2 work together, and the current of the class B power amplifier is equal to the voltage drop across the resistors R1 and R2 divided by the sum of the resistors R1 and R2;

[0044] For the probe in a relatively large second current environment: switch K1 is closed, resistor R2 is short-circuited (no voltage drop), only resistor R1 is effective, and the current of the class B power amplifier is equal to the voltage drop on resistor R1 divided by resistor R1. When the class B amplifier NPN transistor Q1 is turned on, the output positive voltage V1 is equal to the voltage drop between the anode and cathode of diode D1 (about 0.7V) VD1 and the sum of the base and emitter voltage drop Vbe (about 0.7V) of the NPN transistor Q2 of the forward current limiting circuit 1. The output current of the power amplifier is equal to 1.4 / (R1+R2), and the potential at point O is equal to V1-1.4. According to the transistor conduction principle, the NPN transistor Q2 is turned on, and the second amplifier is an NPN transistor. Q2 provides a large collector current; and the large current required by the entire feedback loop can easily and quickly damage the second amplifier, so resistor R3 is used to limit the current provided by the second amplifier, so as to achieve the purpose of protecting the second amplifier. As the probe load increases (the equivalent resistance becomes smaller and smaller), the current flowing through the probe will gradually increase, and finally reach about 1.4 / (R1+R2) when it is limited and no longer increases. The current flowing through resistor R3 will limit the maximum output capacity of the second amplifier, thereby protecting the second amplifier and ultimately limiting the current at the probe load end.

[0045] See also Figure 2-4 As shown, for the probe in a relatively small first current environment. Switch K1 is separated, resistors R1 and R2 work together, and the current of the Class B power amplifier is equal to the voltage drop across resistors R1 and R2 divided by the sum of resistors R1 and R2. If the voltage across resistors R1 and R2 is less than 1.4V, the Class B amplifier outputs voltage and current normally, and the current autonomous protection circuit will not work. Figure 2When the voltage on resistors R1 and R2 is greater than 1.4V, the probe equivalent resistance decreases, that is, the current is greater than 1.4V / (R1+R2), the current autonomous protection circuit takes effect, and the output current is clamped at this current value, as shown in the figure. Figure 3 Although the probe equivalent resistance is further reduced and its output voltage is further reduced, its output current is still clamped at this current, as shown in Figure 4 shown.

[0046] See also Figure 5-7 As shown, for the probe in a relatively large second current environment. Switch K1 is closed, resistor R2 is short-circuited (no voltage drop), only resistor R1 is active, and the current of the Class B power amplifier is equal to the voltage drop on resistor R1 divided by resistor R1. If the voltage on resistor R1 is less than 1.4V, the Class B amplifier outputs voltage and current normally, such as Figure 5 As shown, the current autonomous protection circuit will not work. When the voltage of resistor R1 is greater than 1.4V, the equivalent resistance of the probe decreases, that is, the current is greater than 1.4V / R1, the current autonomous protection circuit works, and the output current is clamped at this current value, as shown in Figure 6 As shown in Figure 1, although the probe equivalent resistance is further reduced and its output voltage is further reduced, its output current is still clamped at this current, as shown in Figure 1. Figure 7 shown.

[0047] In a possible implementation, it further includes: a second amplifier protection loop 3, one end of the second amplifier protection loop 3 is connected to the output of the class B power amplifier, the other end is connected to the reference ground of the class B power amplifier, and the second amplifier protection loop 3 is also connected to the reference ground of the second amplifier. Further, the second amplifier protection loop 3 includes: a resistor R3 and a capacitor C1, one end of the resistor R3 is connected to the output of the class B power amplifier, the other end is connected to the reference ground of the second amplifier and the capacitor C1, and the capacitor C1 is connected to the reference ground of the class B power amplifier.

[0048] Specifically, the second amplifier protection circuit 3 includes a resistor R3 and a capacitor C1, one end of the resistor R3 is connected to point A, the other end of the resistor R3 is connected to the second amplifier reference ground and one end of the capacitor C1, and the other end of the capacitor C1 is connected to the reference ground of the class B power amplifier.

[0049] It can be understood that the circuit design of this scheme can realize autonomous protection of the output current of the linear power amplifier. When the probe load changes, the power amplifier continues to operate according to the control signal to ensure the continuity of diagnostic data. At the same time, compared with other overcurrent protection strategies, this scheme is low-cost, stable and reliable.

[0050] In addition, the current autonomous protection circuit of this solution can theoretically also be used for overcurrent protection of other products, but other products may use fuses or control switches to directly shut down to ensure product safety, which is related to the specific usage environment.

[0051] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A current autonomous protection circuit for a linear power amplifier, characterized in that: include: Multi-stage amplifier, class B power amplifier, forward current limiting circuit, negative current limiting circuit, drive current limiting circuit, feedback circuit and probe; The multi-stage amplifier is connected to the input of the class B power amplifier, the output of the class B power amplifier is connected to the drive current limiting circuit, and the drive current limiting circuit is connected to the probe; The driving current limiting circuit is connected to the input of the multi-stage amplifier through the feedback circuit, the driving current limiting circuit is connected to the NPN transistor of the class B power amplifier through the forward current limiting circuit, and the driving current limiting circuit is connected to the PNP transistor of the class B power amplifier through the negative current limiting circuit; Wherein, the driving current limiting circuit is used to provide two different resistance values.

2. The current autonomous protection circuit for a linear power amplifier according to claim 1, characterized in that: The driving current limiting circuit includes: a resistor R1, a resistor R2 and a switch K1, one end of the resistor R1 is connected to the output of the class B power amplifier, and the other end is connected to the probe through the resistor R2, and the resistor R2 is connected in parallel with the switch K1.

3. The current autonomous protection circuit for a linear power amplifier according to claim 2, characterized in that: When the probe is in a first current environment, the switch K1 is switched off to provide a resistance value of R1+R2; when the probe is in a second current environment, the switch K1 is switched on to provide a resistance value of R1.

4. The current autonomous protection circuit for a linear power amplifier according to claim 3, characterized in that: A current value of the first current environment is smaller than a current value of the second current environment.

5. The current autonomous protection circuit for a linear power amplifier according to claim 1, characterized in that: The forward current limiting circuit includes: an NPN transistor Q2 and a diode D1, the collector of the NPN transistor Q2 is connected to the base of the NPN transistor of the class B amplifier, the base of the NPN transistor Q2 is connected to the cathode of the diode D1, the anode of the diode D1 is connected to the emitter of the NPN transistor of the class B amplifier, and the emitter of the NPN transistor Q2 is connected to the drive current limiting circuit.

6. The current autonomous protection circuit for a linear power amplifier according to claim 1, characterized in that: The negative current limiting circuit includes: a PNP transistor Q4 and a diode D2, wherein the collector of the PNP transistor Q4 is connected to the base of the PNP transistor of the class B amplifier, the base of the PNP transistor Q4 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the emitter of the PNP transistor of the class B amplifier, and the emitter of the PNP transistor Q4 is connected to the driving current limiting circuit.

7. The current autonomous protection circuit for a linear power amplifier according to claim 1, characterized in that: The class B power amplifier includes: an NPN transistor Q1 and a PNP transistor Q2, the bases of the NPN transistor Q1 and the PNP transistor Q2 are connected as the input of the class B power amplifier, the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected as the output of the class B power amplifier, the collector of the NPN transistor Q1 is connected to a positive high voltage, and the collector of the PNP transistor Q2 is connected to a negative high voltage.

8. The current autonomous protection circuit for a linear power amplifier according to claim 1, characterized in that: The multi-stage amplifier includes: a cascaded first amplifier and a second amplifier, wherein the first input end of the first amplifier is connected to a control signal, the second input end is connected to the feedback circuit, the output end is connected to the second amplifier, and the output of the second amplifier is connected to the input of the Class B power amplifier.

9. The current autonomous protection circuit for a linear power amplifier according to claim 8, characterized in that: Also includes: A second amplifier protection loop, one end of the second amplifier protection loop is connected to the output of the class B power amplifier, and the other end is connected to the reference ground of the class B power amplifier. The second amplifier protection loop is also connected to the reference ground of the second amplifier.

10. The current autonomous protection circuit for a linear power amplifier according to claim 9, characterized in that: The second amplifier protection circuit includes: a resistor R3 and a capacitor C1, one end of the resistor R3 is connected to the output of the class B power amplifier, and the other end is connected to the reference ground of the second amplifier and the capacitor C1, and the capacitor C1 is connected to the reference ground of the class B power amplifier.

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