A high-performance micropower switched-capacitor filter

A description is given of a high-performance fifth-order low-pass switched-capacitor filter operating form a single 5-V supply. The filter uses a fully differential topology combined with input-to-output class AB amplifier design, dynamic biasing, and switched-capacitor common-mode feedback. An experimental prototype fabricated in a 5-/spl mu/m CMOS technology requires only 350 /spl mu/W of power to meet the PCM channel filter requirements. Typical measured results are: a dynamic range of 92 dB; a supply rejection (PSRR) of 40 dB over the entire Nyquist range; and a total harmonic distortion of -73 dB for a 2-V r.m.s. differential output signal. The chip active area is about 3900 mil/SUP 2/.