Switched-capacitor filters: precise, compact, inexpensive

Switched-capacitor filters-silicon ICs that combine features of analog and digital filters-are penetrating markets far beyond the telephone networks for which they were first developed. They are now found in audio equipment, speech analyzers and recognizers, test instruments, and electronic musical instruments. Their precision, compactness, and low cost make them preferable to discrete and hybrid filters, as well as to digital filters. Design engineers needing quantities of inexpensive, precise, self-contained filters make switched-capacitor filters (SCFs) their first choice. The author discusses the construction, operation, building blocks, and problems of SCFs.<>