An integrated CMOS current driver using nonlinear feedback for bioimpedance applications

An integrated circuit has been developed for a basic nonlinear negative feedback current driver which isolates the poles required for stability from the high frequency characteristics of the output transconductor. It provides a 1 MHz, 1 mA_p-p current with a phase delay of 16° into a 1kΩ load. While it can be designed as a stand-alone circuit its main use is for application in a proposed circuit using multiple copies of this basic circuit, which significantly extends its high frequency performance by substantially reducing phase delay at high frequencies. The circuit was fabricated in a 0.35-μm CMOS technology and measured results are presented. It is intended for bioimpedance applications.