Dear all,
I use opa657 and opa847 as photodiode’s TIA(bandwidth from 30M to about 100M). But I found one thing that I do not know the name of this effect.
The signal has two parts, a large signal followed by a very small signal. The fig.01below tells the expected signal output.
But it always has very large reverse overdrives after the large signal like fig.02 and sometimes it even larger (reverse cross the noise level) like fig.03.
I tried adding some capacitor to the feedback resistor but it seems not help.
Do you know how to resolve the issue or are there any articles related to the problem?
Thanks very much!
Chengxian,
It would be helpful to have a few more pieces of information to better address this issue. First, do you have a schematic or spice model for the circuit that you could share?
Additionally, regarding the "expected" signal, can you give specific values or ranges of values for the amplitudes of the "large" and "small" signals? What is the time duration of each pulse?
Thanks --
Regards,
Bart Stiller
High Speed Amplifiers