How to DRIVE a piezo driver circuit
Here is a way to do this, using a couple high voltage transistors and an opamp.

The opamp provides precision gain, and allows input-output transfer function down to ZERO input volts.

The first transistor, with base driven from the opamp, is a high voltage NPN, with 2.2Kohm from base to ground, and a 1Kohm in the emitter to ground. The collector connects to the 2nd transistor's base.

The 2nd transistor operates up at 80+ volts, so we have some headroom for precision 75volt output.

The 2nd transistor is a high voltage PNP, with 2.2Kohm from base to +80 volts, and a 1Kohm from emitter to +80 volts. The collector is the high voltage, low current output node. We also use the collector in a feedback path.

Now we implement FEEDBACK for the precision behavior. Connect a 74,000 ohm resistor from collector of the PNP, to emitter of the NPN.

You now have current_mode feedback discrete circuit, with rather fast loop behavior.

What to do with the opamp, so we can remove the error introduced by the NPN's Vbe of 0.5 -- 0.7 volts?


Let me think about this for a while.