Symbolic pole and zero estimation for circuit design

This paper presents a new method for the calculation of symbolic expressions for poles and zeros of linear circuits. The method makes use of different well-known approximation algorithms, which have been applied successfully to obtain simplified transfer functions. A special sensitivity based error criterion controls pole and zero movements and guarantees very compact and also very accurate symbolic expressions for most poles and zeros. The method is realized within the circuit design system EASY. Analyses demonstrate the quality of the method and demonstrate the application for circuit design. A two stage bipolar operational amplifier is considered as an example