I have a circuit which produces a (not high speed) signal between 0 and 9 volts with an adjustable slope, and I would like to increase this output voltage to between 0 and 200 volts, which keeping it ground referenced.
Currently, I am using a PNP transistor connected as a common emitter, which is controlled by an NPN transistor and the output of the lmv358 op amp (the spice model I'm using comes from this website. Here is the schematic in LTSPICE:
Everything works as expected when I run an operating point simulation, but when I try a transient simulation, I get huge oscillations and the simulation rarely has time to finish:
(this is the voltage accross R3; it should be 4 volts).
What have I done wrong? I haven't been able to find similar circuits online, which suggests that maybe I'm missing something sort of obvious. How is something like this usually done?
Thanks!