0.8-V CMOS $G_{m}-C$ Bandpass Filter for Electrical Bioimpedance Spectroscopy

A low-voltage CMOS second-order
$G_{m}-C$
bandpass filter is presented. Three different bulk-driven transconductors are analyzed and compared in terms of effective transconductance and linear input voltage range. The best-performing solution has been selected to implement a biquadratic
$G_{m}-C$
bandpass filter intended to be used in electrical bioimpedance spectroscopy. The filter was designed in 180-nm CMOS technology to operate with 0.8 V of supply voltage. The proposed solution features a center frequency at 72.7 kHz with a power consumption of
$24\ \mu \mathrm{W}$
and is able to process rail-to-rail differential input voltage signals, i.e.,
$800\ \mathrm{m}V_{pp}$
, with a THD below −40 dB.