A high voltage amplifier

Abstract

The invention relates to the field of detection technology, and discloses a high-voltage amplifier, including a differential amplifier circuit, two operational amplifiers, a voltage amplifier circuit and a current amplifier circuit; the voltage amplifier circuit is used for voltage amplification, and the current amplifier circuit is used for current amplification; the two output ends of the differential amplifier circuit are respectively connected to the input ends of the two operational amplifiers, and the output ends of the two operational amplifiers are both connected to the input end of the voltage amplifier circuit; the output end of the voltage amplifier circuit is connected to the input end of the current amplifier circuit; the output end of the current amplifier circuit is connected to the target load; an RC series circuit is connected between the output end of the voltage amplifier circuit and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit. The RC series circuit, on the basis of suppressing the high-frequency self-excited oscillation of the amplifier, prevents the problem of reducing the slew rate and transient response performance of the amplifier due to the connection of the high-frequency negative feedback capacitor, and improves the high-frequency performance of the high-voltage amplifier.

Description

Technical Field

[0001] The present application relates to the field of signal detection technology, and in particular to a high voltage amplifier. Background Art

[0002] High-voltage amplifiers are widely used in signal detection, test and measurement, and other fields. The simplest implementation of a high-voltage amplifier is to use an operational amplifier, which only requires the design of a simple peripheral circuit to work.

[0003] In some related technologies, the maximum output voltage of the high-voltage amplifier is usually between 90-100V, but it is difficult to meet some scenarios that require higher voltage output. For example, some signal detection and test measurements in controlled nuclear fusion devices may require an output voltage of more than 200V, or even more than 500V.

[0004] In some other related technologies, there are some high-voltage operational amplifiers whose output voltage levels can meet the output voltage requirements of controlled nuclear fusion devices. However, such high-voltage operational amplifiers are not only expensive, but also have poor high-frequency performance in actual applications of controlled nuclear fusion devices. For example, a triangular wave signal with a frequency of around tens of kilohertz that needs to be amplified will be significantly distorted.

[0005] Therefore, how to improve the high-frequency performance of high-voltage amplifiers has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] In view of this, the present application provides a high-voltage amplifier to solve the technical problem of how to improve the high-frequency performance of the high-voltage amplifier mentioned in the above background technology.

[0007] The high-voltage amplifier provided in the present application includes a differential amplifier circuit, two operational amplifiers, a voltage amplifier circuit and a current amplifier circuit; the voltage amplifier circuit is used for voltage amplification, and the current amplifier circuit is used for current amplification; the two output ends of the differential amplifier circuit are respectively connected to the input ends of the two operational amplifiers, and the output ends of the two operational amplifiers are both connected to the input end of the voltage amplifier circuit; the output end of the voltage amplifier circuit is connected to the input end of the current amplifier circuit; the output end of the current amplifier circuit is connected to the target load; an RC series circuit is connected between the output end of the voltage amplifier circuit and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit.

[0008] In one embodiment, the voltage amplifier circuit includes two voltage amplifier bridge arms with the same structure and component parameters, and the input end of each current amplifier bridge arm is connected to the output end of the two operational amplifiers, wherein each voltage amplifier bridge arm includes a first high-voltage-withstand transistor and a second high-voltage-withstand transistor with opposite polarities; the bases of the first high-voltage-withstand transistor and the second high-voltage-withstand transistor are connected to the output end of the operational amplifier; the emitter of the first high-voltage-withstand transistor is connected to a positive power supply, and the emitter of the second high-voltage-withstand transistor is connected to a negative power supply; the collector of the first high-voltage-withstand transistor is connected to the collector of the second high-voltage-withstand transistor through a bias circuit, and the collector of the first high-voltage-withstand transistor and the collector of the second high-voltage-withstand transistor are connected to the input end of the current amplifier circuit; the RC series circuit is connected between the collectors of the first high-voltage-withstand transistor and the second high-voltage-withstand transistor and the ground respectively.

[0009] In one embodiment, a collector load resistor is connected in parallel at both ends of the RC series circuit.

[0010] In one embodiment, an operational amplifier load resistor is connected to the output end of the operational amplifier; and emitter resistors are respectively connected to the emitters of the first high withstand voltage transistor and the second high withstand voltage transistor.

[0011] In one embodiment, the bias circuit includes: a bias transistor and a variable resistor, the collector of the bias transistor is connected to the collector of the first high withstand voltage transistor, the emitter of the bias transistor is connected to the collector of the second high withstand voltage transistor, and the base of the bias transistor, and the variable resistor is connected between the collector and base of the bias transistor.

[0012] In one embodiment, the current amplification circuit includes a bridge push-pull amplifier circuit, the input end of the current amplification bridge arm of the bridge push-pull amplifier circuit is connected to the output end of the voltage amplifier circuit, and the current amplification bridge arm of the bridge push-pull amplifier circuit includes a third high withstand voltage transistor and a fourth high withstand voltage transistor with opposite polarities; the base of the third high withstand voltage transistor is connected to the collector of the first high withstand voltage transistor, and the base of the fourth high withstand voltage transistor is connected to the collector of the second high withstand voltage transistor; the collector of the third high withstand voltage transistor is connected to the positive power supply, and the collector of the fourth high withstand voltage transistor is connected to the negative power supply; the emitter of the third high withstand voltage transistor is connected to the emitter of the fourth high withstand voltage transistor, and is connected to the target load.

[0013] In one embodiment, a first base resistor is connected between the base of the third high withstand voltage transistor and the collector of the first high withstand voltage transistor; a second base resistor is connected between the base of the fourth high withstand voltage transistor and the collector of the second high withstand voltage transistor.

[0014] In one embodiment, the high-voltage amplifier also includes: an overcurrent protection circuit, connected between the collector of the first high-voltage withstand transistor and the emitter of the third high-voltage withstand transistor, and connected between the collector of the second high-voltage withstand transistor and the emitter of the fourth high-voltage withstand transistor.

[0015] In one embodiment, the target load is an inductive load; and a load vibration elimination circuit is provided at the output end of the current amplifying circuit.

[0016] In one embodiment, the current amplification circuit includes a high-voltage Darlington transistor or a plurality of high-voltage triodes connected in parallel.

[0017] Compared with the prior art, this application has at least the following technical effects:

[0018] The output end of the differential amplifier circuit is respectively connected to the input ends of the two operational amplifiers, and the output end of the operational amplifier is connected to the input end of the voltage amplifier circuit; the output end of the voltage amplifier circuit is connected to the input end of the current amplifier circuit; the output end of the current amplifier circuit is connected to the target load; an RC series circuit is connected between the output end of the voltage amplifier circuit and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit. When the amplifier circuit composed of the operational amplifier and the voltage amplifier circuit amplifies the voltage signal, the amplified signal will have a phase shift. Under the influence of this phenomenon, the high-voltage amplifier will produce high-frequency self-oscillation. If the high-frequency self-oscillation is suppressed by a high-frequency negative feedback capacitor, the slew rate and transient response performance of the high-voltage high-frequency signal will be significantly reduced. Therefore, an RC series circuit is connected between the output end of the voltage amplifier circuit and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit. The RC series circuit acts as a high-frequency attenuation circuit to reduce the high-frequency gain of the amplifier and play a phase lag role on the high-frequency signal. At the same time, it can prevent the amplifier from generating high-frequency self-oscillation, and can effectively avoid the problem of reducing the slew rate and transient response performance of the amplifier caused by increasing the high-frequency negative feedback capacitor, thereby improving the high-frequency performance of the high-voltage amplifier.

[0019] Furthermore, in order to meet the high voltage output, two groups of single-ended high voltage amplifiers are connected into a BTL amplifier circuit, and the output voltage is twice as high as the output voltage of a conventional single-ended amplifier circuit. The voltage amplification and current amplification transistors used in the high voltage amplifier are selected from products with high voltage resistance and good frequency characteristics to ensure a sufficiently high output voltage and good high frequency characteristics of the high voltage amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a modular schematic diagram of a high voltage amplifier according to an embodiment of the present invention;

[0022] Figure 2 is a circuit diagram of a high-voltage amplifier including a voltage amplification bridge arm of a voltage amplification circuit according to an embodiment of the present invention;

[0023] Figure 3 is a circuit diagram of another voltage amplifying bridge arm including a voltage amplifying circuit according to an embodiment of the present invention;

[0024] Figure 4 is a circuit diagram of a high-voltage amplifier including a current amplifying bridge arm of a bridge push-pull circuit according to an embodiment of the present invention;

[0025] Figure 5 is another circuit diagram of a high-voltage amplifier including a current bridge arm of a bridge push-pull circuit according to an embodiment of the present invention;

[0026] Figure 6 is a circuit diagram of a high-voltage amplifier including an overcurrent protection circuit according to an embodiment of the present invention;

[0027] Figure 7 is a circuit diagram of a high voltage amplifier including a current bias circuit according to an embodiment of the present invention;

[0028] Figure 8 is a circuit diagram of a high voltage amplifier according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Generally, in order to improve the high-frequency characteristics of the amplifier, a high-frequency negative feedback capacitor is often required to be provided between the collector and the base of the triode of the voltage amplification stage in the amplifier to prevent the amplifier from generating high-frequency self-oscillation. However, the inventors have found that in actual applications, when the amplifier in the related art is applied to a controlled nuclear fusion device, some output signals will be significantly distorted, especially some high-voltage triangular wave output signals with a frequency of tens of kilohertz will be significantly distorted. The inventor has found that the amplifier in the related art has a high-frequency negative feedback capacitor set between the collector and base of the triode of the voltage amplification stage to prevent the amplifier from generating high-frequency self-oscillation, and the high-frequency negative feedback capacitor has a certain reduction effect on the slew rate and transient response performance of the amplifier. In some low-voltage scenarios, the output voltage swing of the amplifier is small, so the high-frequency negative feedback capacitor has little effect on the slew rate and transient response performance of the amplifier. However, in the scenario of high voltage demand in the field of controlled nuclear fusion, the voltage swing of the amplifier output is very large, causing the high-frequency negative feedback capacitor to abruptly amplify the slew rate and transient response performance of the amplifier, and the Miller capacitance of the triode in the amplifier has a great influence on the high-frequency characteristics of the amplifier, for example, reducing the slew rate and transient response performance at high frequency; if the high-frequency negative feedback capacitor is still connected to the collector and base of the triode, the high-frequency characteristics of the amplifier will become worse, however, if the high-frequency negative feedback capacitor is removed, the amplifier will also cause high-frequency self-oscillation. Therefore, the amplifier in the related art is difficult to meet the application in the controlled nuclear fusion device.

[0031] Based on this, the embodiment of the present application provides a high voltage amplifier, such as Figure 1 and Figure 8 As shown, the high-voltage amplifier includes a differential amplifier circuit 100, two operational amplifier ICs, a voltage amplifier circuit 200 and a current amplifier circuit 300; the voltage amplifier circuit 200 is used for voltage amplification, and the current amplifier circuit 300 is used for current amplification; the two output ends of the differential amplifier circuit 100 are respectively connected to the input ends of the two operational amplifier ICs, and the output ends of the two operational amplifier ICs are both connected to the input end of the voltage amplifier circuit 200; the output end of the voltage amplifier circuit 200 is connected to the input end of the current amplifier circuit 300; the output end of the current amplifier circuit 300 is connected to the target load; an RC series circuit 400 is connected between the output end of the voltage amplifier circuit 200 and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit 200.

[0032] In this embodiment, the input signal is converted into two signals of equal magnitude and opposite phase by the differential amplifier circuit 100. The differential amplifier circuit 100 can be implemented in a variety of ways. For example, a differential amplifier dedicated chip can be used, and an operational amplifier can also be used to build a differential amplifier circuit.

[0033] For the voltage amplification of the output signal of the differential amplifier circuit 100, a negative feedback network needs to be connected between the input and output ends of the high voltage amplifier, such as Figure 8 The feedback resistor R21 and the feedback capacitor C2 are connected in parallel to determine the gain of the high voltage amplifier. In order to more conveniently implement the negative feedback network to determine the gain of the high voltage amplifier, a two-stage amplification is adopted in this embodiment. First, the voltage of the signal output by the differential amplifier circuit 100 is amplified by the operational amplifier IC, and then the voltage is amplified by the voltage amplifier circuit 200 cascaded at the output end of the operational amplifier IC. However, when the amplifier circuit composed of the operational amplifier IC and the voltage amplifier circuit 200 amplifies the voltage signal, the amplified signal will have a phase shift. Under the influence of this phenomenon, high-frequency self-oscillation will be generated in the high-voltage amplifier. If the high-frequency self-oscillation is suppressed by a high-frequency negative feedback capacitor, the slew rate and transient response performance of the high-voltage high-frequency signal will be significantly reduced. Therefore, in this embodiment, an RC series circuit 400 is connected between the output end and the ground of the voltage amplifier circuit 200 to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit 200. The RC series circuit 400 is used as a high-frequency attenuation circuit. The higher the frequency, the smaller the impedance of the RC series circuit 400 to the high-frequency signal, the smaller the voltage of the high-frequency signal input to the current amplifier, and the lower the high-frequency gain of the high-voltage amplifier. The RC series circuit 400 also plays a phase lag role on the high-frequency signal. Improving the high-frequency phase margin of the high-voltage amplifier can prevent the amplifier from generating high-frequency self-oscillation, and can effectively avoid the problem of reducing the slew rate and transient response performance of the high-voltage amplifier caused by increasing the high-frequency negative feedback capacitor, thereby improving the high-frequency performance of the high-voltage amplifier.

[0034] In one embodiment, in order to meet the high-voltage output, a voltage-enhancing circuit 200 in the form of BTL connection is used for voltage amplification, which is twice as high as the output voltage of a conventional single-ended amplifier circuit. Therefore, in this embodiment, a high-voltage transistor can be used to build a voltage amplification circuit. In order to meet the voltage resistance requirements and achieve better linear output in the high-voltage amplification scenario, a high-voltage transistor with high voltage resistance and good frequency characteristics is used as a linear amplifier device to build a voltage-enhancing circuit in the form of BTL connection. For example, power transistors with a voltage resistance of more than 350V are often designed for switching applications, with poor frequency characteristics and low amplification factors; however, among power transistors with a voltage resistance of more than 350V, some have good frequency characteristics and high amplification factors, and their voltage resistance can reach 600V. Therefore, they can be used in the scenario of high-voltage linear amplification. The BTL connection method can achieve a maximum output voltage of about 550V. And through the RC series circuit 400 connected between the output end and the ground of the voltage amplifier circuit 200 in the present application, the high-frequency negative feedback capacitor in the voltage amplifier circuit 200 is replaced, the high-frequency gain of the amplifier is reduced, and the phase lag effect is played on the high-frequency signal, which can compensate for the high-frequency characteristics of the high-voltage transistor to a certain extent. The high-voltage amplifier built with high-voltage transistors can better match the usage scenarios in the present application. At the same time, the RC series circuit 400 can prevent the amplifier from generating high-frequency self-oscillation, and can effectively avoid the problem of reducing the slew rate and transient response performance of the amplifier caused by increasing the high-frequency negative feedback capacitor.

[0035] As an exemplary embodiment, Figure 8 As shown, the voltage amplifier circuit 200 has two voltage amplifier bridge arms 210 with the same circuit structure and component parameters; the two voltage amplifier bridge arms 210 are respectively connected to the output terminals of the two operational amplifier ICs. Figure 8 The technical solution of the present application is described by taking a voltage amplifying bridge arm 210 in the voltage amplifying circuit 200 as an example; exemplarily, Figure 2 is a circuit diagram of a high voltage amplifier including a voltage amplifying bridge arm 210 of a voltage amplifying circuit 200 according to an embodiment of the present invention, such as Figure 2 As shown, the voltage amplifying bridge arm 210 of the voltage amplifying circuit 200 includes a first high withstand voltage transistor Q1 and a second high withstand voltage transistor Q2 with opposite polarities.

[0036] The first high-voltage transistor Q1 can be a PNP transistor, and the second high-voltage transistor Q2 can be an NPN transistor; the inverting input terminal of the operational amplifier IC is connected to the output terminal of the differential amplifier circuit 100; the emitter and base of the first high-voltage transistor Q1 and the second high-voltage transistor Q2 are connected to the output terminal of the operational amplifier IC; the emitter of the first high-voltage transistor Q1 is connected to the positive power supply VCC+, the emitter of the second high-voltage transistor Q2 is connected to the negative power supply VCC-, the collector of the first high-voltage transistor Q1 is connected to the collector of the second high-voltage transistor Q2 through a bias circuit, and the collector of the first high-voltage transistor Q1 and the collector of the second high-voltage transistor Q2 are connected to the input terminal of the current amplifier circuit 300; wherein, an RC series circuit 400 is connected between the collectors of the first high-voltage transistor Q1 and the second high-voltage transistor Q2 and the ground, respectively. Figure 2 As shown, the RC series circuit 400 may include a first series circuit 410 connected to the collector of the first high withstand voltage transistor Q1 and a second series circuit 420 connected to the collector of the second high withstand voltage transistor Q2.

[0037] The first series circuit 410 and the second series circuit 420 can reduce the high-frequency gain of the high-voltage amplifier when the first high-voltage transistor Q1 and the second high-voltage transistor Q2 act as voltage amplification devices, and have a phase lag effect on the high-frequency signal. The implementation method of connecting the first series circuit 410 and the second series circuit 420 in the circuit replaces the method of connecting a high-frequency negative feedback capacitor between the collector and the base of the first high-voltage transistor Q1 and the second high-voltage transistor Q2 in the related art. On the basis of suppressing the high-frequency self-excited oscillation generated by the high-voltage amplifier, the problem of reducing the slew rate and transient response performance of the amplifier due to connecting a high-frequency negative feedback capacitor is prevented, thereby improving the high-frequency performance of the high-voltage amplifier.

[0038] For example, the operational amplifier IC is selected to have high output voltage and good high-frequency performance, which is conducive to further improving the high-frequency performance of the high-voltage amplifier; Figure 8 As shown, since the input voltage and output voltage of the two voltage amplifier bridge arms in the voltage amplifier circuit 200 are opposite, the signal must be input from the reverse input terminal of the operational amplifier IC to ensure that the input signal and the output signal have the same phase.

[0039] See also Figure 2As shown, the output end of the operational amplifier IC is connected to an operational amplifier load resistor 510, wherein the operational amplifier load resistor 510 may include a first operational amplifier load resistor R1, a second operational amplifier load resistor R2, a third operational amplifier load resistor R3, and a fourth operational amplifier load resistor R4. The smaller the resistance value of the operational amplifier load resistor 510, the greater the output current of the operational amplifier IC. If the output current capability of the operational amplifier IC is strong, the value of the operational amplifier load resistor 510 can be reduced. In the high-voltage amplifier in the present application, the operational amplifier load resistor 510 can also be configured with a heat dissipation module to dissipate the loss heat of the operational amplifier load resistor 510 to ensure the performance of the high-voltage amplifier.

[0040] In one embodiment, the operational amplifier load resistor 510 can also be used as a bias resistor for the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2 to determine the static current value of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2. In another embodiment, the base of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2 can also be connected to a base resistor ( Figures 2 to 8 The first base resistor R5 and the second base resistor R6 shown in the figure are used to further stabilize the static current of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2.

[0041] In one embodiment, an emitter resistor ( Figures 2 to 8 R7 and R8 shown in the figure are used to stabilize the static operating points of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2 without being affected by temperature.

[0042] In one embodiment, in order to further improve the high frequency performance of the amplifier, a collector load resistor ( Figures 3 to 8 In the present embodiment, a collector load resistor is provided between the collector of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2 and the ground, and the collector load resistor is connected in parallel with the RC series circuit 400. For example, Figure 3 As shown, the first and second series circuits 410 and 420 are respectively connected in parallel with a first load resistor R11 and a second load resistor R12. The first load resistor R11 and the second load resistor R12 can reduce the collector load resistance value of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2, thereby appropriately reducing the amplification factor of the first high withstand voltage transistor Q1 and the second high withstand voltage transistor Q2, and reducing the collector voltage swing, so as to reduce the influence of the transistor Miller capacitance on the high frequency performance of the amplifier, and further improve the high frequency performance of the high voltage amplifier.

[0043] As an exemplary embodiment, the current amplifying circuit 300 may adopt a BTL connection circuit, such as Figure 4 As shown, the current amplifier circuit 300 includes a bridge push-pull amplifier circuit, such as Figure 8 As shown, the bridge push-pull amplifier circuit has two current amplifier bridge arms 310 with the same structure and component parameters, and the input ends of the two current amplifier bridge arms 310 are both connected to the output end of the voltage amplifier circuit. Figure 4 The circuit structure of one current amplifying bridge arm 310 of the bridge push-pull amplifier circuit is shown as an example, and the technical solution of the present application is described by taking one current amplifying bridge arm 310 of the bridge push-pull amplifier circuit as an example. Figure 4 In the embodiment, the current amplifying bridge arm 310 of the bridge push-pull circuit includes a third high withstand voltage transistor Q3 and a fourth high withstand voltage transistor Q4 with opposite polarities.

[0044] Among them, Figure 4 As shown, the base of the third high withstand voltage transistor Q3 is connected to the collector of the first high withstand voltage transistor Q1, and the base of the fourth high withstand voltage transistor Q4 is connected to the collector of the second high withstand voltage transistor Q2; the collector of the third high withstand voltage transistor Q3 is connected to the positive power supply VCC+, and the collector of the fourth high withstand voltage transistor Q4 is connected to the negative power supply VCC-; the emitter of the third high withstand voltage transistor Q3 is connected to the emitter of the fourth high withstand voltage transistor Q4, and is connected to the target load.

[0045] Exemplarily, the third high withstand voltage transistor Q3 may be an NPN transistor, and the fourth high withstand voltage transistor Q4 may be a PNP transistor.

[0046] In one embodiment, if Figure 4 As shown, a third base resistor R13 is connected between the base of the third high withstand voltage transistor Q3 and the collector of the first high withstand voltage transistor Q1;

[0047] A fourth base resistor R14 is connected between the base of the fourth high withstand voltage transistor Q4 and the collector of the second high withstand voltage transistor Q2 to stabilize the static current of the third high withstand voltage transistor Q3 and the fourth high withstand voltage transistor Q4 from being affected by temperature and reduce high frequency oscillation of the high voltage amplifier.

[0048] In order to further stabilize the static operating points of the third high withstand voltage transistor Q3 and the fourth high withstand voltage transistor Q4, in this embodiment, a first emitter resistor R15 is connected in series to the emitter of the third high withstand voltage transistor Q3, and a second emitter resistor R16 is connected in series to the emitter of the fourth high withstand voltage transistor Q4.

[0049] In one embodiment, the target load is an inductive load, and the output terminal of the high-voltage amplifier and the output resistor form a signal phase shift circuit to generate self-excited oscillation. Therefore, Figure 4 As shown, a load vibration elimination circuit 430 is provided at the output end of the high voltage amplifier to prevent high frequency oscillation caused by the high voltage amplifier being connected to an inductive load.

[0050] As an exemplary embodiment, Figure 5 As shown, the high voltage amplifier includes an overcurrent protection circuit 600, which is connected between the collector of the first high withstand voltage transistor Q1 and the emitter of the third high withstand voltage transistor Q3, and between the collector of the second high withstand voltage transistor Q2 and the emitter of the fourth high withstand voltage transistor Q4.

[0051] As a practical embodiment, the overcurrent protection circuit 600 may include a fifth high withstand voltage transistor Q5 having the same polarity as the third high withstand voltage transistor Q3 and a sixth high withstand voltage transistor Q6 having the same polarity as the fourth high withstand voltage transistor Q4.

[0052] like Figure 5 As shown, the base of the fifth high withstand voltage transistor Q5 is connected to the emitter of the third high withstand voltage transistor Q3 through a resistor; the collector of the fifth high withstand voltage transistor Q5 is connected to the collector of the third high withstand voltage transistor Q3 through a first diode D1; wherein, the cathode of the first diode D1 is connected to the collector of the fifth high withstand voltage transistor Q5, and the anode of the first diode D1 is connected to the collector of the first high withstand voltage transistor Q1; the base of the sixth high withstand voltage transistor Q6 is connected to the emitter of the fourth high withstand voltage transistor Q4 through a resistor; the collector of the sixth high withstand voltage transistor Q6 is connected to the collector of the fourth high withstand voltage transistor Q4 through a second diode D2, wherein, the cathode of the second diode D2 is connected to the collector of the sixth high withstand voltage transistor Q6, and the anode of the second diode D2 is connected to the collector of the second high withstand voltage transistor Q2.

[0053] The overcurrent protection circuit 600 may also be in the form of a voltage comparator and a transistor switch circuit.

[0054] As an exemplary embodiment, the bias circuit 700 of the high voltage amplifier is connected in series between the collector of the first high withstand voltage transistor Q1 and the collector of the second high withstand voltage transistor Q2. Figure 6As shown, the bias circuit 700 includes a bias transistor Q7 and a variable resistor R19, the collector of the bias transistor Q7 is connected to the collector of the first high withstand voltage transistor Q1, the emitter of the bias transistor Q7 is connected to the collector of the second high withstand voltage transistor Q2, the base of the bias transistor Q7, and the variable resistor R19 is connected between the collector and the base of the bias transistor Q7. In the bias circuit 700, the static current of the third high withstand voltage transistor Q3 and the fourth high withstand voltage transistor Q4 can be adjusted by adjusting the resistance value of the variable resistor R19.

[0055] The bias circuit 700 further includes a first capacitor C1 and a first resistor R20, wherein the first capacitor C1 is connected in parallel between the emitter and collector of the bias transistor Q7, and one end of the first resistor R20 is connected to the base of the bias transistor Q7, and the other end is connected to the emitter of the bias transistor Q7.

[0056] In another embodiment, the bias circuit may further include two diodes connected in series, wherein the anode of one diode is connected to the collector of the first high withstand voltage transistor Q1 , and the cathode of the other diode is connected to the collector of the second high withstand voltage transistor Q2 .

[0057] In one embodiment, in order to improve the load capacity of the high-voltage amplifier, the current amplifier circuit 300 can use a high-voltage Darlington transistor in a Darlington connection mode, or multiple high-voltage triodes connected in parallel to increase the output current of the high-voltage amplifier.

[0058] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0059] In the several embodiments provided in the present application, it should be understood that the device embodiments described above are only schematic, such as the division of units, which is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0060] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution provided in this embodiment.

[0061] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0062] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0063] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A high voltage amplifier, characterized in that: include: A differential amplifier circuit, two operational amplifiers, a voltage amplifier circuit and a current amplifier circuit; the voltage amplifier circuit is used for voltage amplification, and the current amplifier circuit is used for current amplification; The two output ends of the differential amplifier circuit are respectively connected to the input ends of the two operational amplifiers, and the output ends of the two operational amplifiers are both connected to the input end of the voltage amplifier circuit; wherein the voltage amplifier circuit comprises two voltage amplifier bridge arms with the same structure and component parameters; each of the voltage amplifier bridge arms is respectively connected to the output end of the operational amplifier; The output end of the voltage amplifier circuit is connected to the input end of the current amplifier circuit; the output end of the current amplifier circuit is connected to the target load; wherein the current amplifier circuit comprises a bridge push-pull amplifier circuit, the bridge push-pull amplifier circuit comprises two current amplifier bridge arms with the same structure and component parameters, and the input end of each current amplifier bridge arm is connected to the output end of the voltage amplifier circuit; An RC series circuit is connected between the output end of the voltage amplifier circuit and the ground to replace the high-frequency negative feedback capacitor in the voltage amplifier circuit.

2. The high voltage amplifier according to claim 1, characterized in that Each of the voltage amplifying bridge arms comprises a first high withstand voltage triode and a second high withstand voltage triode with opposite polarities; The bases of the first high withstand voltage transistor and the second high withstand voltage transistor are connected to the output end of the operational amplifier; The emitter of the first high withstand voltage transistor is connected to a positive power supply, and the emitter of the second high withstand voltage transistor is connected to a negative power supply; The collector of the first high withstand voltage transistor is connected to the collector of the second high withstand voltage transistor through a bias circuit, and the collector of the first high withstand voltage transistor and the collector of the second high withstand voltage transistor are connected to the input end of the current amplification circuit; The RC series circuit is connected between the collectors of the first high withstand voltage transistor and the collectors of the second high withstand voltage transistor and the ground, respectively.

3. The high voltage amplifier according to claim 2, characterized in that The two ends of the RC series circuit are connected in parallel with a collector load resistor.

4. The high voltage amplifier according to claim 2, characterized in that An operational amplifier load resistor is connected to the output end of the operational amplifier; Emitter resistors are connected to emitters of the first high withstand voltage transistor and the second high withstand voltage transistor, respectively.

5. The high voltage amplifier according to claim 2, characterized in that The bias circuit includes: a bias transistor and a variable resistor, the collector of the bias transistor is connected to the collector of the first high withstand voltage transistor, the emitter of the bias transistor is connected to the collector of the second high withstand voltage transistor, and the base of the bias transistor, and the variable resistor is connected between the collector and the base of the bias transistor.

6. The high voltage amplifier according to claim 2, characterized in that Each of the current amplifying bridge arms comprises a third high withstand voltage triode and a fourth high withstand voltage triode with opposite polarities; The base of the third high withstand voltage transistor is connected to the collector of the first high withstand voltage transistor, and the base of the fourth high withstand voltage transistor is connected to the collector of the second high withstand voltage transistor; The collector of the third high withstand voltage transistor is connected to the positive power supply, and the collector of the fourth high withstand voltage transistor is connected to the negative power supply; An emitter of the third high withstand voltage transistor is connected to an emitter of the fourth high withstand voltage transistor and is also connected to the target load.

7. The high voltage amplifier according to claim 6, characterized in that A first base resistor is connected between the base of the third high withstand voltage transistor and the collector of the first high withstand voltage transistor; A second base resistor is connected between the base of the fourth high withstand voltage transistor and the collector of the second high withstand voltage transistor.

8. The high voltage amplifier according to claim 6, wherein: Also includes: The overcurrent protection circuit is connected between the collector of the first high withstand voltage transistor and the emitter of the third high withstand voltage transistor, and is connected between the collector of the second high withstand voltage transistor and the emitter of the fourth high withstand voltage transistor.

9. The high voltage amplifier according to claim 1, wherein: The target load is an inductive load; A load vibration elimination circuit is arranged at the output end of the current amplifying circuit.

10. The high voltage amplifier according to claim 1, wherein: The current amplifying circuit includes a high-voltage Darlington transistor or a plurality of high-voltage triodes connected in parallel.

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