Exact simulation of feedback circuit parameters

Techniques for finding the important parameters of a single-loop feedback circuit at the closed-loop DC operating point are presented. The main advantage of these techniques is that they allow exact computer simulation of feedback parameters with a circuit simulator such as SPICE. Maintaining the closed-loop DC bias point in all test circuits makes it possible for the circuit simulator to compute the small-signal models for all nonlinear elements correctly. The methods presented for simulating loop transmission are particularly valuable since they can be used to accurately determine gain and phase margin using frequency-domain analysis, which is faster and more efficient than simulating step response via transient analysis. The equations behind the two methods for calculating loop transmission are presented as background. Examples are included to demonstrate the techniques