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AD8131 stability against load capacitance

Question asked by saguaro on Oct 19, 2015
Latest reply on Nov 6, 2015 by saguaro

Hi there,

I am trying to assess the AD8131 stability (phase margin) against output capacitance. I thought that one of the easiest way would be using the ADIsimOpAmp Op-Amp Stability Evaluation Tool on the ADI site. However some needed input data such as:

- Open loop gain, A0

- Unity-gain frequency

are NOT found in the datasheet. All the gain and frequency data is related to the internal feedback resistors, but in this case it is unusable as the stability calculation needs the pure amplifier (without feedback network) data.

Does anybody know the above data or how to derive them, maybe from the SPICE model?

Other stability evaluation methods are welcome too...

* Currently the AD8131 SPICE model in under work since several bugs have been found.