sapna wrote on Jan 22nd, 2012, 2:36am:i will derive the gain and phase margin in open loop configuration and look at its stability .i hope this is the correct method.
It is the correct PRINCIPLE.
If the applied method is correct depends....
You should know that opening of a feedback loop may cause problems (bias point lost, loading condtions altered). For this purpose, some specific methods have been proposed (Middlebrook method, series injection,..)