Signal flow graph analysis of feedback amplifiers

A systematic way of transcribing the schematic of an integrated circuit into its signal flow graph (SFG) equivalent is presented. With this SFG, transfer functions, loop gains, and input and output impedances are readily computed. The analysis is valid for multiloop amplifiers and the computation of a three-stage amplifier with nested Miller compensation is presented to illustrate the robustness of the method. Two theorems of SFG relating the stability of networks are also derived.