CN100342641C - High-voltage amplifier - Google Patents

Abstract

A high-voltage amplifier, which includes GAIN signal buffer amplification (1), BIAS signal buffer (2), inverting amplifier (3), driver (4), amplifier (5), final stage power amplifier (6), linear DC regulator The power supply (7) is characterized in that the BIAS signal output by the signal buffer (2) is input to the preamplifier circuit (8), and the digital signal processed by it is connected to the relay control circuit (9) to control the relay control circuit The relay (J) in (9) gains and loses power, and the switching function of the switch switching circuit (10) is realized by the relay (J) gaining and losing power; the described linear DC stabilized voltage power supply (7) includes low-frequency interference Inhibition circuit (11). When the amplifier is turned on and off, there is no surge voltage and kickback voltage at the high-voltage output, and the stability of the high-voltage output reaches ≤±0.2%. The safety, stability and reliability of the load are guaranteed.

Description

high voltage amplifier

Field

The invention relates to a high-voltage amplifier, in particular to a high-voltage amplifier with stable output.

technical background

The high-voltage amplifier is a function signal that outputs adjustable DC high voltage or DC high voltage modulation in the amplification mode, and is used for precision electronic instruments in open-loop or closed-loop control systems. If it is used in the laser field, it can also be used as a high-voltage DC voltage source, etc.

In the prior art, such as the high-voltage amplifier of the GD-1 type produced by the Institute of Optoelectronic Technology of the Chinese Academy of Sciences in China, and the high-voltage amplifier of the burleigh MODEL PZ-70 type produced by U.S.A. Burleigh Instrument, Inc. abroad (see the product manual).

This high-voltage amplifier includes GAIN signal buffer amplification and BIAS signal buffer. The two signals are mixed and input to the inverting amplifier, and then the output signal of the inverting amplifier is input to the driver to drive the amplifier. The output signal of the amplifier is sent to the final power amplifier. The function signal of DC high voltage or DC high voltage modulation obtained by the power amplifier is sent to the output terminal of the high voltage amplifier (HV OUT), and the linear DC regulated power supply provides high voltage regulated power supply for the amplifier and the final power amplifier. signal output. The DC high voltage can be adjusted arbitrarily from 0 to 1000VDC, and the function signal output can be adjusted arbitrarily from 0 to 500V _pp .

This high-voltage amplifier outputs DC high voltage. If the load is piezoelectric ceramics, the DC voltage applied to both ends of the piezoelectric ceramics is as high as 1000V, or even higher, and the load current is as high as 20mA. In an instant, a high-voltage step pulse will be superimposed on the output DC high voltage on the high-voltage output terminal (HV OUT), which will cause the load to overload the load instantaneously, affect the reliability of the load, and even damage the load. Even if the BIAS of the high-voltage amplifier is turned to 0 (equivalent to turning off the high voltage), the kickback voltage will still be generated because the voltage across the capacitor of the high-voltage output circuit cannot change suddenly. If the BIAS of the high-voltage amplifier is turned on in the high-voltage output preset state, a surge voltage (high-voltage step pulse) will be generated at the high-voltage output terminal at the moment of power-on, which will also endanger the safe operation of the load.

In addition, there is 10HZ-200HZ, 50mv _pp -8v _pp low-frequency interference at the output terminal (HV OUT) of this high-voltage amplifier, and the output DC high-voltage stability of the whole machine is ≤±1%.

Contents of the invention

The purpose of the present invention is to provide a high-voltage amplifier with high stability. When the amplifier is turned on and off, the high-voltage output terminal does not generate surge voltage and kickback voltage, and can overcome the impact of low frequency (ripple) on the output terminal of the high-voltage amplifier. interference.

The invention provides a high-voltage amplifier, including GAIN signal buffering and amplification, BIAS signal buffering, the two signals are mixed and input to the inverting amplifier, and then the output signal of the inverting amplifier is input to the driver to drive the amplifier, and the output signal of the amplifier is sent to the final stage Power amplifier, the function signal of DC high voltage or DC high voltage modulation obtained by the final stage power amplifier is sent to the output terminal of the high voltage amplifier (HV OUT), and the linear DC regulated power supply provides high voltage regulated power supply for the amplifier and the final stage power amplifier. In the amplification mode, the high voltage amplifier will The DC high-voltage modulation function signal output is characterized in that the BIAS signal output through the signal buffer is input to the input port V _S of the preamplifier circuit, and the digital signal processed by the preamplifier circuit is connected to the relay control circuit through the resistor _R4 The input terminal b is used to control the gain and loss of power of the relay J in the relay control circuit. Through the gain and loss of power of the relay J, the switching function of the switch switching circuit is realized, and the switching of the output port of the high-voltage amplifier to the ground short circuit and open circuit is completed, and the POWER automatically Switch between protection and release of self-protection. This design prevents surge voltage and kickback voltage from being generated at the high-voltage output terminal when the high-voltage amplifier is turned on or off; the two ends of the four rectifier diodes in the linear DC stabilized power supply are each connected in parallel with a high-voltage capacitor to form a Low-frequency interference suppression circuit, so that the interference of low-frequency (ripple) below 200Hz on the output of the high-voltage amplifier is as small as possible, so as to improve the stability of the output high voltage; the described preamplifier circuit is composed of DC or low-frequency integrated operational amplifier U Non-inverting amplifier circuit, R ₂ and R ₃ are feedback resistors, R ₁ is an isolation resistor, diode D ₁ limits the BIAS signal of the non-inverting input terminal of DC or low-frequency integrated operational amplifier U to ≤0.7V, and the output terminal voltage of operational amplifier U is controlled by Zener diode D ₂ is limited to 2V to 3V; the relay control circuit is sent to the base b of the transistor VT in the relay control circuit by the BIAS digital signal output by the preamplifier circuit through the current limiting resistor R ₄ . An anti-ringing capacitor C is connected between the base b and ground.

Compared with prior art, advantage and effect of the present invention: 1) have adopted bias signal preamplifier circuit, relay control circuit, relay switch contact and high-voltage output (HV OUT) circuit in the high-voltage amplifier of the present invention, make high-voltage amplifier When starting up, the high-voltage output terminal is at zero potential (ground) and the high-voltage output terminal does not generate surge voltage; before shutting down, the high-voltage output is reduced to zero (that is, the BIAS signal is reduced to zero), and the relay J is de-energized. The POWER self-protection is released before it can be shut down. At this time, the high-voltage output is zero, and the high-voltage output terminal is switched to the ground at the same time, which avoids the occurrence of kickback voltage. Ensure the safety and reliability of the load. 2) The low-frequency interference suppression circuit is adopted in the high-voltage amplifier of the present invention, which improves the stability of the output of the high-voltage amplifier, so that only the ripple level of 50 Hz does not exceed 100 mV _PP , and the stability of its high-voltage output reaches ≤ ± 0.2%. It is obviously superior to the technical performance of the prior art American PZ-70 high-voltage amplifier. The following table is a comparison between the present invention and the U.S. burleighPZ-70 high-voltage amplifier:

Description of drawings

Fig. 1 is the circuit block diagram of high voltage amplifier of the present invention

Fig. 2 is the part principle circuit diagram of high voltage amplifier of the present invention

In the figure: 1: GAIN signal buffer amplification; 2: BIAS signal buffer; 3: inverting amplifier; 4: driver; 5: amplifier; 6: final stage power amplifier; 7: linear DC regulated power supply; 8: BIAS signal front Amplification; 9: relay control circuit; 10: switch switching circuit; 11: low-frequency interference suppression circuit.

Detailed ways

The high-voltage amplifier of the present invention will be further described in detail below in conjunction with the accompanying drawings.

A high-voltage amplifier is shown in Figure 1 and Figure 2, including GAIN signal buffer amplification 1, which is an external function signal, buffered and amplified GAIN signal through a non-inverting amplifier and an analog input voltage composed of a reference voltage , the BIAS signal after the buffer 2 is input to the inverting amplifier 3 together. At the same time, the BIAS signal output by the signal buffer 2 is input to the input port V _S of the preamplifier circuit 8, and the digital signal processed by the preamplifier circuit 8 is connected to the input terminal b of the relay control circuit 9 through the resistor _R4 , To control the relay J in the relay control circuit 9 to gain and lose power, realize the switching function of the switch switching circuit 10 through the gain and lose power of the relay J, complete the switching of the high-voltage amplifier output port to ground short circuit and open circuit, and POWER self-protection and Switching of self-protection release. The inverting amplifier 3 is composed of an integrated operational amplifier and a feedback circuit connected to its non-inverting terminal. The feedback circuit feeds back the output voltage of the final output terminal of the high-voltage amplifier to the non-inverting terminal. After the GAIN and BIAS signals are processed by the inverting amplifier, a DC modulation is obtained. The function signal of the driver is sent to the driver 4 to amplify the current to drive the amplifier 5 to amplify the DC voltage or the DC modulated function signal to the required amplitude. The voltage is output from its collector to the base of the final power amplifier 6. The final power amplifier 6 is composed of the same transistor as the amplifier 5 to form an emitter follower. The emitter output circuit of the final power amplifier 6 is divided by three precision resistors. The obtained DC voltage or the function signal voltage modulated by the DC voltage is sent to the HV OUT port (BNC), the other part is fed back to the non-inverting input terminal of the inverting amplifier 3, and the third part is sent to the digital display to display the high voltage through the display circuit. DC voltage output from amplifier HV OUT port. The low-voltage power supply of the whole machine is provided by a linear constant voltage source or a switching power supply, and the high-voltage power supply is provided by a linear DC regulated power supply 7 to the amplifier 5 and the final stage power amplifier 6 . A high-voltage capacitor is connected in parallel at the two ends of the four rectifying diodes of the linear DC stabilized voltage power supply 7 . In this way, the interference of the low frequency (ripple) below 200Hz on the output of the high-voltage amplifier is as small as possible, so as to improve the stability of the output high voltage. The high-voltage amplifier outputs the DC high-voltage modulation function signal in an amplification mode.

Wherein: the preamplifier circuit 8 is composed of a DC or low-frequency integrated operational amplifier U to form a non-inverting amplifying circuit, R ₂ and R ₃ are feedback resistors, R ₁ is an isolation resistor, and diode D ₁ integrates the DC or low-frequency integrated operational amplifier U The BIAS signal at the non-inverting input terminal of the U is limited to ≤0.7V, and the voltage at the output terminal of the operational amplifier U is limited to 2V～3V by the Zener diode _D2 .

Described relay control circuit 9 is sent into the base pole b of the crystal triode VT in the relay control circuit by the BIAS digital signal output by the preamplifier circuit 8 through the current-limiting resistor _R4 , and connects one between the base pole b and the ground. Anti-ringing capacitor C. Said crystal triode VT is a medium and small power transistor. The capacitance of the capacitor C is greater than or equal to 10 μF.

The relay J is a medium and small power DC relay. The switch switching circuit 10 is that the knife K ₁ in a group of SPDT switches of the relay J is connected to the high-voltage output port of the high-voltage amplifier, and its normally closed contact is grounded, and the knife K ₂ in the other group of SPDT switches and the normal The open contacts are respectively connected with two contacts of the power switch of the high voltage amplifier.

When the high-voltage amplifier is turned on, no surge voltage is generated at the high-voltage output terminal; no kickback voltage is generated when the power is turned off; the stability of the high-voltage output reaches ≤±0.2%. The safe, stable and reliable operation of the load is guaranteed. After the application test on the laser by the Institute of Optoelectronics of Shanxi University, it has been proved that its safety, stability and reliability are obviously superior to existing products.

Claims (4)

1. A high-voltage amplifier, comprising GAIN signal buffer amplification (1), BIAS signal buffer (2), input inverting amplifier (3) after two signals are mixed, then the output signal input driver (4) of inverting amplifier (3) ), to push the amplifier (5), the output signal of the amplifier (5) is sent to the final stage power amplifier (6), and the DC high voltage or DC high voltage modulated function signal obtained by the final stage power amplifier (6) is sent to the high voltage amplifier output terminal (HV OUT ), the linear DC regulated power supply (7) provides a high-voltage regulated power supply for the amplifier (5) and the final power amplifier (6), and the high-voltage amplifier outputs the DC high-voltage modulation function signal in the amplification mode, and is characterized in that it will pass through the signal buffer ( 2) The output BIAS signal is input to the input port (V _s ) of the preamplifier circuit (8), and the digital signal processed by the preamplifier circuit (8) is connected to the input of the relay control circuit (9) through the resistor _R4 terminal (b), to control the relay (J) in the relay control circuit (9) to gain and lose power, to realize the switching function of the switch switching circuit (10) through the gain and lose power of the relay (J), and to complete the output port of the high-voltage amplifier Switching between short-circuit and open-circuit to ground, and switching between POWER self-protection and self-protection release; each of the two ends of the four rectifier diodes in the linear DC regulated power supply (7) is connected in parallel with a high-voltage capacitor to form a low-frequency interference suppression Circuit (11); described preamplifier circuit (8) is to form the same phase amplifying circuit by direct current or low-frequency integrated operational amplifier (U), R ₂ and R ₃ are feedback resistors, R ₁ is an isolation resistor, and diode (D ₁ ) limit the BIAS signal of the non-inverting input terminal of the DC or low-frequency integrated operational amplifier (U) to ≤0.7V, and the output terminal voltage of the operational amplifier (U) is limited to 2V～3V by the Zener diode (D ₂ ); said relay The control circuit (9) is sent to the base (b) of the crystal triode (VT) in the relay control circuit by the BIAS digital signal output by the preamplifier circuit (8) through the current limiting resistor (R ₄ ), at the base ( b) Connect an anti-ringing capacitor (C) to ground. 2. The high-voltage amplifier according to claim 1, characterized in that: said transistor (VT) is a medium and small power transistor; said capacitor (C) has a capacitance ≥ 10 μF. 3. The high-voltage amplifier according to claim 1, characterized in that: said relay (J) is a medium or small power DC relay. 4. The high-voltage amplifier according to claim 1, characterized in that: said switching circuit (10) is a knife (K ₁ ) in a group of single-pole double-throw switches of a relay (J) connected to the high-voltage output of the high-voltage amplifier port, its normally closed contact is grounded, and the pole (K ₂ ) and normally open contact of another set of single-pole double-throw switches are respectively connected to the two contacts of the power switch of the high-voltage amplifier.

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