High-Voltage Capacitive-Load Amplifier

Design targets

Maximum output

Up to 200 V, unipolar

High-voltage rail

55 V to 225 V

Voltage gain

50 V/V (nominal)

Output source current

150 µA

Output sink current

40 µA

Capacitive load

200 pF

Operating temperature

−10 °C to +85 °C

Practical operating notes

• The output is unipolar: it swings in one polarity only, not symmetrically around zero.
• The linear output range is targeted to begin at about 7 V, so the output is not intended for precise operation near 0 V.
• The top of the linear range must stay below the rail by a margin: about 1.5 V with no load, or about 2.5 V with a 4 MΩ load to ground. Review headroom separately for other load conditions.
• Because of that margin, 200 V is not reachable at every rail setting in the 55–225 V range; the rail must exceed the desired output by at least the margin.
• The 150 µA and 40 µA figures are output-current design targets for charging and discharging small capacitance. They do not confirm suitability for any particular actuator and do not imply continuous or thermally sustained drive.
• Higher load capacitance or faster voltage changes need correspondingly more current, so check the required rate of voltage change against these targets.