MichaelTian
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Posts: 3
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Cri,
There are four loops in this circuit: the loop thru. OP1/upper R2, OP2/lower R2, OP3/upper R4, OP3/lower R4. The first two are single loops, the last two are differential loops.
What you can do is to put a probe on the upper R2 and lower R2 branch, to asses the stability of the first two single loops. Then use the cmdm probe (available in analogLib) and place that on the upper R4 and lower R4 branches to assess the differential mode and common mode loopgain for the differential circuit.
If all loopgain shows good stability margin, you should have confidence on the design. Also you can run pz analysis to double check the whole circuit.
Mike
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