Approximate Symbolic Pole/Zero Expressions of a Band-stop Filter
Alexandru Gabriel Gheorghe, Mihai Eugen Marin, Cristina Gabriela Bortosu · 2021 XXX International Scientific Conference Electronics (ET) · 2021
Pole/zero expressions as a function of circuit parameters are essential for circuit designers. Because the exact symbolic expressions become complex even for small circuits, a number of programs designed to compute the numerical or the poles and zeros approximate symbolic expressions have been developed. In this paper a procedure able to compute both the numerical and the approximate symbolic poles and zeros expressions of a circuit is used for a band-stop filter. The numerical values obtained with this procedure are compared with those computed by Hspice and SapWin. The approximate symbolic pole/zero expressions are used to generate the transfer function of the filter and its frequency characteristic is compared with the result of an a.c. analysis. Several design solutions starting from the computed pole/zero approximate symbolic expressions are discussed.