Hi, team,
In customer's circuit test, there is some ringing at OPA2333AQDRQ1 output side, they just add one 1k resistor to reduce the ringing as shown below.
Could you give some analysis method to judge whether 1k resistor is good enough in this design? Will it influence below circuit design?
Thanks.
Johnny
Hi Johnny,
I ran a phase stability analysis and can confirm that the OPA2333 is unstable without isolation resistor because of a total erosion of phase margin:
With an isolation resistor of 1k, on the other hand, the phase response is ideal and the OPA2333 is stable:
The only disadvantage is that any load current will cause a voltage drop across the 1k resistor. If the load current is very small, the additional voltage drop might be negligible. But if this is not the case, I would look at the "dual feedback" method.
See also the TI's OPAmp stability learning videos, especially episodes 3 and 6:
Kai
