Dynamic-Range Analysis and Maximization of Micropower Gm-C Bandpass Filters by Adaptive Biasing

We analyze and present an input gain-varying scheme for maximizing dynamic range in a well-known G(m)-C bandpass filter by both minimizing noise for small input signals, and by achieving balanced swing levels at all filter nodes for large input signals. A micropower bandpass filter suitable for use in cochlear implants and other power. constrained biomedical applications was implemented and tested in subthreshold CMOS. At a center frequency of 1.4kHz and quality factor of 4, the filter has 70dB of dynamic range (57dB maximum SNR, 2.5% total harmonic distortion (THD)) and consumes 2.55 mu W of power.