Design of continuous-time fully integrated filters: a review

The paper summarises fundamental concepts and methods used for designing continuous-time (C-T) signal-processing circuits (‘filters’) in fully integrated form. The resulting filter structures can be integrated together with other parts of the system on the same chip, compatible with all IC technologies. A design procedure is discussed which leads to the minimal set of components that are theoretically required for the implementation of monolithic C-T filters. The problem of automatic tuning against fabrication tolerances and component drifts during operation is discussed. Examples are presented to illustrate the promising results that can be achieved when designing C-T fully integrated filters.