ABSTRACT

This chapter describes in some detail the features of S/FILSYN, a general-purpose filter synthesis and design program, that uses the combination method just described for the numerical calculations. It considers a more general approximation procedure that works with the transfer function, thereby permitting the possible specification of the delay as well. In the early 1970s that program was completely rewritten to be used for educational purposes at Cornell University and was renamed FILSYN. The first commercial version of this program made its appearance in 1975, now handling passive LC filters as well as active RC and digital filters. The selection of configuration for active RC filters is much simpler. If transconductance amplifiers are used as active elements, the circuit selected is unique. Once a satisfactory circuit is obtained, it can be analyzed, stored in a data file, or printed for documentation purposes. Data transfer files are also available to a number of other Computer-Aided Design programs for further processing.