RC Active Filters for the D3 Channel Bank

Resistance-capacitance active filters are a relatively new addition to the family of frequency selective networks. Although active filters have been in existence for 20 years, they have not been widely used because passive filters have been less expensive. However, the concurrent development of silicon integrated circuits, tantalum thin-film technology, and automated computer-controlled test sets have made RC active filters a practical alternative to passive filters at voice frequencies. This paper deals with the design and development of the voicefrequency RC active filters used in the D3 channel bank. 1 ' 2 These filters are realized in thin-film tantalum technology with beam-leaded silicon integrated-circuit operational amplifiers on one ceramic substrate. 507 New analysis4-5 and modeling techniques, more efficient optimization algorithms, 6 the concept of statistical design,7 and more flexible machine aids to physical design gave the network designers powerful tools with which to attack the design process.