A Practical Approach for Analysis of Input and Output Impedances of Feedback Amplifiers

This paper suggests a pedagogical approach to teaching the subject of the analysis of feedback amplifiers for electrical engineering students at the undergraduate level. Special attention is given to derivation of the input and output impedances. In order to make the procedure clear and suitable for classroom presentation an alternative proof of the Blackman´s Impedance Relation is derived to stand in accord with feedback amplifier analysis methodology presented earlier. The proposed analysis technique is algorithmic, comprehensive, suited to any feedback topology, and is especially useful in cases that do not readily stand out as one of four canonical cases of feedback. The methodology is demonstrated by examples, and supported by comparison with simulation and other theoretical results.