Hi;

I want to simulate the loop gain in a bandgap circuit with an amp, I can put a dc voltage to break the loop in three place:
1. positive input of the amp(negetive feedbak);
2. negetive input of the amp(positive feedbak);
3. the output of the amp;

in the above cases, which is the right configuration?

BTW, if I want to get the positive loop gain and negetive loop gain seperately , how can I use stb?