Signal Flow Graph Analysis of Analog Circuits using Principles of Control Theory : Tutorial Review

This tutorial paper discusses an efficient approach that can be adopted to analyze complex analog circuits. The approach is specifically designed to show the graphical interdependencies between system nodes and variables and has been validated across multiple engineering disciplines. By utilizing this graphical approach, we reduce the dependency on circuit analysis techniques that often requires solving extensive systems of simultaneous equations as while effective, they become increasingly difficult and error-prone when applied to circuit with numerous voltage nodes. This paper presents an alternative approach that utilizes basic small-signal analysis principles, Gain Formula from control theory to derive the transfer functions of the circuit or its sub-circuits. The method simplifies the analysis process by directly providing closed-form expressions for the transfer function. This approach not only reduces the general difficulty of the circuit analysis but also minimizes the potential for algebraic mistakes, which are common when working with analytical techniques. Furthermore, it removes the guesswork typically involved in the simplification process found in many textbook examples, where assumptions or approximations are often employed to simplify complex circuits.