On loop-impedance matrix formulation of feedback amplifier theory

The generalized cofactor and the second-order generalized cofactor of the elements of the loop-impedance matrix in a system of basic circuits are defined. The cofactor can be used to calculate the network functions, return differences, null return differences, and sensitivities of basic circuits within the framework of feedback amplifier theory. It is shown that the cofactors are very similar to cofactors derived by means of an indefinite-admittance matrix. The application of the loop-impedance and indefinite-admittance matrices to different types of circuit networks is discussed.