High Speed High Voltage Amplifier

2016.05.24

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HV Amplifier

High voltage amplifier converts input voltage to high voltage waveform as it is as shown in fig. 1. These days the demand of HV amplifier is growing more and more, and now becoming an indispensable tool for research and development, experiments and integrating to a system for such fields as electronics, physics, biochemical and medical industries. With high voltage technologies Matsusada Precision Inc. manufactures various HV amplifiers to meet all requirements from customers.

* In addition to these models in this catalog we have amplifiers developed specially for electrostatic chuck or PZT. Please ask for details to our sales staff.

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Four-quadrant Output Range

HV amplifier is generally equipped with the "sink" function for output currents that provides constant voltage operation without regard to the type of load whether it is capacitive or conductive. (Fig.2) As it gives fast response, it is an ideal power supply for applications which require AC output.
Matsusada HV amplifiers are all bi-polar type and can be operated in full four-quadrant area.(I · II · III · IV area)

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Slew Rate

The responsibility of our high speed amplifier is determined with slew rate(SR). The step responsibility of our amplifier is as shown in fig.3.
SR = V / μS In case of output amplitude is smaller the response time become shorter.
AMP series reach to greater than SR =700V / μS at maximum.

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Rise Time(step response)

Step response can be indicated with rise time. (fig.4) Usually the rise time of amplifier of response (= bandwidth)fc (Hz) is given by a formula below.
tr ≒ 0.35 / fc
The fall time tf is equals to tr.

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Frequency Response

Response of Matsusada amplifiers are described as "frequency bandwidth". When swing the output with sinusoidal waveform with rated resistive load, output swing (amplitude) is reduced as input frequency become faster. Frequency response in the specification is the frequency fc is where output swing is 70% (-3dB). (fig. 5)
In case clear output waveform is required, please select a HV amplifier which has high enough frequency bandwidth against required frequency.
In general 3 to 5 times more frequency bandwidth for sinusoidal waveform, and about 10 times more for rectangular waveform, is required. In case of insufficient frequency bandwidth the output swing shall be reduced, and also the phase difference be large, so some solutions, such as monitoring output waveform, shall be required.

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Capacitive Load

When operated with a capacitive load of more than 100pF(including floating capacity of output cable), the output might oscillate. In such a case put a high voltage resister of 100Ω(0.1μF) to 1kΩ(1000pF) in series to output. Please also note that with capacitive load the bandwidth is limited according to the formula of right note.
In case of corona discharge, larger current than rating can draw and night damage power supply.
In this case too place an output resister to limit the current as same as in case of with capacitive load.

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Important note to utilize the full performance of high speed HV amplifier

Output cable of HV amplifiers is not shielded. If the output cable has some stray capacity against ground(earth ground or metal objects), output voltage will be sinusoidal or step waveform and extra current will be drawn. As this current draw parallel to load, the following appearance might be happened.

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