Other Parts Discussed in Thread: OPA180,
As far as I know, the ideal open-loop output impedance of an op amp should be as low as possible.
But I see the open-loop output impedance of opa192 is really high especially at low frequency. Nevertheless, the OPA180 has a low output impedance. Let us call the output impedance "Zo".
Question 1: Can you please tell me what type op amps have lower output impedance and what type have high output impedance? And what advantages can be brought if the Zo is high?
Question 2: In what situations is high Zo op amp more appropriate? And same question to low Zo op amp.
Question 3: I know the Zo can be reduced significantly by the loop gain of the op amp. What will be affect by these two parameter respectively? the open-loop Zo and closed-loop Zo?
Question 4: As for stability of amp, the isolated resistor is related to the open-loop Zo right? I found some equations like Riso = Ro * Rg/Rf. If the Ro is high like 1k , the Riso will be large. But the value of Riso is small in most examples, even in the application notes of the amp with high Zo.
Looking forward to your reply.
Thanks.