I am using the OPA847 as front-end amplifier for an EMAT acquisition module, as in the schematic below:
It works as expected without C4, but how we need to limit the bandwidth due to external noise, by adding it the amplifier becomes unstable. In that case, just by connecting a 50R termination resistor in CN1 it oscillates.
I tried to use C8 (220pF) as described in the datasheet to compensate C4, but the result is even worse.
According with the Spice simulation it should work in that conditions. What may be causing that unstability?