High voltage OPAMP / PREAMP

I am working on a high voltage opamp for the pre-amp to a MOSFET voltage follower. What do you guys think about this schematic?

I am planning on using SOT-223 ZETEX HIGH Voltage Devices for the diff amp stage and there High current devices in the output stage.

I want this thing to operate at +/-100v and drive a mosfet power follower. Caps are TBD values. I dont have a good spice program yet to simulate.


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2002-02-06 9:16 pm
For a free spice version: http://www.winspice.com/
No schematic entry, but fast.

- 2 small resistors (50-300 Ohm) in series with the emitors of the curent mirror Q1 Q2
- 2 even smaller resistors (10-30 Ohm) in series with the input pairs emitor Q4 Q5
- use leds to bias the current sources, zeners can be very noisy
- take a look at transistors meant for video stages, plenty of gain and voltage.