I use an OPA350 to buffer the ADC's unbuffered voltage output (VCOM). The ADC's VCOM pin provides a voltage output equal to AVDD/2 to set the output common-mode level of the analog input drivers - in this case, 8 differential amplifiers VOCM.
The OPA350's output, which is now the buffered ADC VCOM (+2.5V), powers the output common-mode pins (VOCM) of 8 differential amplifiers that sets the DC output voltage. Each differential amplifier's VOCM input contains one 0.1uF, one 1uF, and one 10uF decoupling capacitor to filter high-frequency noise. Per the differential amplifier's datasheet, a 0.1-μF or 1-μF capacitor is generally adequate so I may be overdoing it with the 10uF decoupling cap.
My questions are:
1) Is the total output load capacitance too much for the OPA350 to drive? Could it cause oscillation/instability on the output?
2) Should I add an isolation resistor such as a 100 ohm resistor in series with the output of the OPA350 to help reduce instability/oscillation?
3) Should I add a 100 ohm resistor in series between the output of the ADC's VCOM pin and the input of the OPA350 to reduce parasitic noises? The recommended VCOM output on the ADC does not have a series resistor and only recommends using a 0.1uF bypass capacitor to reduce noise pickup.
Thank you
