A Low-Distortion Current-Mode Signal Generator for Wide-Range Bioimpedance Spectroscopy

This paper presents a low-distortion current-mode sinusoidal signal generator for bioimpedance spectroscopy measurements. The proposed full current-mode operation enables linearity enhancement and potential savings in silicon area and power consumption. Programmability in the low-pass filter and current driver enables impedance measurements from
$0.2\ \Omega$
to
$10\ \mathrm{k}\Omega$
over a wide frequency range from 1 kHz to 1 MHz. The current generator, designed in a
$0.18\ \mu \mathrm{m}$
CMOS process, consumes between
$736\ \mu \mathrm{W}$
at the lowest frequency and gain, and 1.70 mW at the highest frequency and gain, and occupies 1.76 mm
²
silicon area. Post-layout simulation results show a spurious-free dynamic range larger than 40 dBc over the entire frequency range, which enables bioimpedance measurements with errors below 1%, as it is required for wearable devices evaluating neuromuscular disorders.