Tool/software:
Hi,
I am using the OPA378 in a unity-gain aka voltage follower configuration. The load is a couple of 0.1 uF capacitors along with the parasitic capacitance of some IC inputs. The input is a DC voltage that is supplied by a reference. I've noticed that the output of the OPA378 oscillates at a low frequency (~ 150 kHz) and the oscillation waveform is a low-amplitude sinusoid. I can quell these oscillations by inserting an Riso (R408 as shown in the figure below). I'm curious why an Riso given that the OPA378 is described as unity-gain stable in the datasheet. Is it perhaps because it's a chopper amplifier and fc=150 kHz which matches the frequency of the sinusoid?
Thanks,
James
