A 2.4 Hz-to-10 kHz-tunable biopotential filter using a novel capacitor multiplier

This paper describes a high-dynamic-range 2.4 Hz-to-10 kHz wide-range tunable 5
^th
-order Butterworth lowpass filter for biomedical applications. A differential g
m
-C topology in conjunction with a subthreshold-biased wide-g
m
-range OTA realizes efficiently a wide frequency tuning capability. For capacitance savings with consequent silicon area reduction, a merged use of floating real capacitor and grounded multiplier-based capacitor is proposed. Optimized in a 0.35-µm CMOS process, the filter achieves over 68-dB dynamic range, 64 dB stopband attenuation and 28 µW power consumption at a single 3-V supply.