I need a clipper for a 10 kHz signal to protect an ADC from possible overvoltage. I'm using the usual active circuit (simulation is in multisim):
Unfortunately the result is very bad, the opamp is too slow to respond. I tried adding compensation capacitor C1 but no luck.
The problem is magnified if I give a square wave signal at the input. Then the output gets all the way to Vdd. I also attempted to give the bias voltage as a Vdd source for the opamp but then the diode drop gets in the way messing up the signal. I've tried the circuit in reality and it works like in multisim.
Is there a way to remove the spikes, even in the square wave signal? If possible without significant phase shift.
EDIT: I forgot to mention that the input stage is actually an in-amp,the AD8226 with a slew rate of 0.6V/us. Also,the C3 cap is there because i have integrated the ADC input filter with the clipper. I suppose that this may slow down the response of the clipper,so i moved it's input to BEFORE R15. No luck again. Seems that LM358 is too slow. A fast opamp solves the problem,but i'm wondering if i can slow down the slew rate of the AD8226? Tried adding a 100pF from it's output to GND but did't help.