A new self Q-tuning scheme for biquad OTA-C filters

Abstract

A new Q-tuning scheme for biquad OTA-C filters is presented. We have taken benefit of the advantages of the classical Phase-Locked Loop scheme to tune the center frequency and we have also applied it to Q-tuning. The unique requirement for these biquad filters is that fo-tuning and Q-tuning must be uncoupled and independent. Tunability and versatility of OTAs have been fully exploited attaining quality factors with accuracy errors smaller than 1%.