Symbolic Analysis of Linear Amplifiers with Multi-Loop Feedbacks in Interacting Programs Maple and FASTMEAN

A technique of interaction of computer programs for symbolic analysis of complex electronic circuits with amplifying elements is proposed. FASTMEAN simulation program, used in the universities of telecommunications in Russia, has a symbolic analysis module and is capable of generating analytical expressions for Laplace images of a circuit determinant, currents and voltages in complex electronic circuits. However, the obtained expressions have a nested (folded) structure, which makes it difficult to analyze the influence of elements on the properties of a circuit with amplifiers and feedbacks, in particular on its stability. It is proposed to transfer the obtained expressions to  Maplе program for their structural transformation and mathematical processing.                       .          Amplifiers with local, common and crossed feedbacks are considered. The analysis of such circuits in Maple shows that an expression for the circuit determinant in the form of the products of the loop gain functions is a sign of the presence of several feedback loops in the circuit.