A design program for digital and analogue filters: PANDDA

A new filter design system, PANDDA, is introduced. It has the following distinguishing features: the design of general forms of amplitude and group delay response; easy construction and comparison of the many different filter structures, especially to allow new structures to compete with the popular, well-tested ones; and optimisation methods to improve the performance of circuits within physical constraints. PANDDA has a very general and flexible approximation capability allowing frequency responses to be tailored very closely to the specifications. A wide variety of different filter realisations can be designed and compared quickly. Although the emphasis is on switched-capacitor filter, active-RC and digital filters can also be derived. All filters are stray-insensitive and based on a regular structure suitable for automatic layout on gate-array type chips. The main sections of the program are indicated and their salient features are described