High-sensitivity regulated inverter cascode transimpedance amplifier for near infrared spectroscopy

This paper presents a design and a post layout simulation of a high-sensitivity low-power transimpedance amplifier (TIA) for frequency domain near infrared spectroscopy (FD-NIRS). The TIA consumes 340 μW from a 1.2 V DC supply. This low power is necessary for NIRS device portability. The proposed TIA achieves 104.8 dBΩ transimpedance gain, 50 MHz bandwidth and 15.1 nA_rms total integrated input noise current for 2 pF off chip photodiode capacitance. The demonstrated TIA is simulated using 130 nm CMOS technology and occupies an area of 0.0012 mm². Post amplifier stage is presented to increase the total gain. The complete NIRS optical receiver achieves 119.5 dBΩ gain, 49.2 MHz bandwidth, 15.4 nA_rms total integrated input noise current and consumes 400 μW from a 1.2 V DC supply.