Low-power transimpedance amplifier for near infrared spectroscopy

This paper presents the design and the post layout simulation of a high-sensitivity low-power Transimpedance Amplifier (TIA) for frequency domain functional Near Infrared Spectroscopy (FD-fNIRS). It consumes 194 μW from 1.2 V DC supply. This low power will increase the battery life of the NIRS portable system. The proposed TIA achieves 103.3 dBΩ transimpedance gain, 22 MHz bandwidth and 6.3 nA integrated input noise current using a photodiode with 2 pF capacitance. The demonstrated TIA is simulated using 130 nm CMOS technology occupying an area of 0.0012 mm
²
. Post amplifier stages are presented to increase the total gain and to interface the ADC in the next stage. The complete receiver achieves 120.6 dBΩ gain, 19.9 MHz bandwidth, 6.6 nA total input noise and consumes 2.4 mW from 1.2 V DC supply.