Set-UP: I am using an OPA657 as a transimpedance amplifier. I have a 10MHz, passive, RC filter on the front end (100pF, 160 ohms), The OPA 657 has filter caps on the +5/-5V terminals of .1uF and 6.8uF. My gain resistor is 1.6K with a feedback cap of 0.7pF.
Problem: If I have nothing connected to the input of the OPA I have a ringing of 145MHz, if I put a lower impedance (just wire leads or bnc leads) it drops to 85MHz, if i put in a 75 ohm into the input it has 130MHz of ringing. What am I doing that is causing this substantial ringing?
Notes: End game I am putting in a 20-30nS pulse, amplifiying it, into a 0-3V uC input. Right now I am just working with the first stage OPA657 as a transimpedance amplifier. I also power it externally with a dual output power supply +5/-5V, to avoid any added noise from the power lines.