A wideband CMOS current driver for bioimpedance applications with output DC regulation

Bioimpedance measurements are performed in a wide range of frequencies (100Hz to 1MHz) as physiological tissue information is scattered throughout this frequency band. Wideband current drivers with high output impedance are essential to maintain high injected current accuracy over a wide range of load impedances. The purpose of the work presented in this paper is the design methodology of a fully integrated, wideband current driver for bioimpedance measurement systems. The circuit has been designed and simulated in a standard CMOS 0.6-um technology delivering currents of up to 2mA pk-pk operating from a ±6V power supply. Results show an output current phase delay of -2.43° at 1MHz and an output impedance of 8MΩ at 100Hz reducing to 1.08MΩ at 1MHz.