I use OPA890 or OPA690 as a unity gain buffer. But the output show a small oscillation.
According the datasheet, I directly connect Output and inverting input in using OPA890 ,and
connect Output and inverting input with a 25Ω resistor in using OPA690.
Add a small resistor below 100 ohm at output for driving pure CAPACITIVE LOAD about 50p.
But After I doing all this, a small oscillation still exist for 200mV p-p.
Are these two amp not suitable for unity gain buffer?