Low-Power Variable-Gain CMOS Trans Impedance Amplifier for Near Infra-Red Spectroscopy Applications

A novel low-power and variable gain CMOS Trans Impedance Amplifier (LP-VG-TIA) circuit design for Near Infra-Red Spectroscopy (NIRS) Applications is presented in this paper. The proposed low power and variable gain CMOS Trans Impedance Amplifier achieves a variable gain from 55.06 dBΩ to 119.81 dBΩ with a minimum bandwidth of 12.46 MHz and a maximum bandwidth of 25.33 MHz. The variable gain control is used to achieve different values of the gain and the bandwidth for multiple bio-medical sensor applications. The input-referred noise with photodiode (PD) model with 1pF capacitance is 1.6pA
rms
. The maximum input photocurrent is 1uA
p-p
. The proposed LP-VG-TIA consumes 95.3 µW at a room temperature of 27 °C from a 1V power supply. The proposed circuit has been implemented using a GPDK 45nm CMOS process. The proposed low power and variable gain TIA outperforms the existing TIAs in the literature.