I'm using the AD5725 operating with the following input ranges : +/- 5V , +/-10V and any combination in between that doesn't violate the operating condition of VREF.
Since I'm using the +/-10V reference, I placed a 0.22uF bypass capacitor at inputs. The reference IC is a precise one : ADR01 and its voltage output is configured through a 4 matched resistor array to provide the various reference voltage. The ADA4077-4 is the buffer used for VREF inputs.
However, after experimenting some transitions from -10V to -5V as an example, the added 0.22uF bypass capacitor is adding a pole that causes oscillation at VREFN. Adding a series resistor seems to prevent the op amp from oscillating, however, adding a RC snubber doesn't... Is there any explanation based on the mentioned components that would explain why the snubber doesn't affect at all the ringing observed?
Regards,
Carl Trudeau
