Abstract
This paper presents the design and post layout simulation of a high dynamic-rang and low-power transimpedance amplifiers (TIA) for frequency domain near infrared spectroscopy (FD-NIRS). The proposed TIA achieves 108.3 dB Omega gain, 10 MHz bandwidth, and 5.5 nA(rms) integrated input referred noise using a photodiode with 2 pF capacitance. The proposed TIA consumes 260 mu W from a 1.2 V supply. The maximum input photocurrent is extended to 9.2 mu A(p-p) with the adopted automatic gain control (AGC). A post amplifier with AGC is introduced after the TIA to increase the gain of the optical receiver and to maintain a good linearity. The complete optical receiver achieves 122 dB Omega gain, 9.9 MHz bandwidth, 5.9 nA(rms) total integrated input noise current, and consumes 1.44 mW from a 1.2 V supply.