A 24 μW 38.51 mΩrms resolution bio-impedance sensor with dual path instrumentation amplifier

This paper presents a low power, high resolution bio-impedance sensor IC for respiration monitoring application. It contains the dual path instrumentation amplifier (DPIA) including current reusing transconductance amplifier and high gain transimpedance amplifier for high resolution, low power and wide input range bio-impedance measurement. Measured results show that the proposed readout circuit has 354 nV
rms
input noise and 2.12 μW of the lowest power consumption along with the widest differential input range of 52 mV
pp
as well. As a result, the readout circuit enables bio-impedance sensor IC to uphold a comparable 38.51 mΩ
rms
impedance resolution with a relatively smaller 26 μA
pp
injection current than previous works. This leads to a 24 μW of lowest overall power consumption of bio-impedance sensor. In this sense, the proposed bio-impedance sensor IC achieves its figure of merit (FoM) by value that is 4 times lower compared to the state-of-the-art.