I might be misunderstanding something here, so feel free to correct me. But the problem with your original circuit was that it went from -15V to +3.2V, right? And it needed to go from -15V to 0V. Well, a diode would accomplish that, although it would drop ~0.5V when conducting, but that shouldn't matter too much.If you used a diode to remove the bias, you'd have to ensure that there was a constant current flow through it, or the voltage wouldn't be very stable. It would add to the parts count, too.
by Duane Benson
by Jake Hertz
by Aaron Carman
by Aaron Carman