0.6‐V CMOS bulk‐driven instrumentation amplifier for IoMT bioimpedance analysis

Abstract

An instrumentation amplifier (IA), aimed at wideband bioimpedance analysis in the low‐voltage low‐power scenario of internet of medical things (IoMT), is presented. The operation principle is based on the indirect current feedback technique, where an input and a feedback transconductor determine the voltage gain of the preamplifier. The required transconductors consist of two bulk‐driven flipped‐voltage‐follower cells and an active pseudo‐resistor, thus leading to a linear and compact implementation. The circuit has been designed and fabricated in 180 nm CMOS technology to operate with a 0.6‐V supply. Experimental results obtained from measurements on eight samples of the silicon prototype show that when the IA is programmed to have a nominal voltage gain of 11 V/V, the bandwidth is 316.2 kHz, the CMRR exceeds 63 dB, and the maximum output voltage that can be processed with a THD below –40 dB is 555 mV .