The Biquad: Part I-Some practical design considerations

The use of active elements in linear networks offers new degrees of freedom to both network and system designers. A comprehensive report on the Biquad, an active topology based on analog computer concepts, is given. We describe the electrical characteristics of the Biquad that make it a manufacturable realization for precision networks. Analysis and experimental data describe the dependence of Biquad performance on nonideal operational amplifiers. Compensation techniques are derived which allow high- operation at several hundred kilohertz with existing devices. The 8-V rms signal capacity and 80-dB dynamic range of the voice-frequency Biquad are illustrated.