Low-voltage programmable gm-C filter for hearing aids using dynamic gate biasing

This paper presents a low voltage programmable continuous-time filter for hearing aids. The filter uses an analog circuit technique employing on-chip charge pumps called dynamic gate biasing (DGB). A simple method for reducing the ripple from the DGB charge pumps is presented. The principle of DGB is experimentally verified through the implementation of a programmable g_m-C biquadratic filter. Designed in 0.35 μm CMOS, the filter operates from 1.2 V and dissipates 16 μW, provides 62.3 dB dynamic range at -45 dB THD and can realize lowpass, bandpass and highpass filter responses.