Automatic filter design: the development of a CAD system

Describes the results of a project jointly funded by British Telecom and the SERC to create a user friendly filter design system. The system can be easily used by people who have some knowledge of filters but are not experienced in the techniques of filter synthesis. The project has concentrated on the synthesis of LC ladder filters. The user is not involved in unnecessary details of the approximation and circuit synthesis stages. To achieve this the approximation routine can automatically make an initial estimate of the order of the filter and the pole positions. At the synthesis stage a routine is used to automatically decide the order of pole removal