A Sub-Microwatt Low-Noise Amplifier for Neural Recording

In this paper we present a pre-amplifier designed for neural recording applications. Extremely low power dissipation is achieved by operating in an open-loop configuration, restricting the circuit to a single current branch, and reusing current to improve noise performance. Our amplifier exhibits 3.5 microVrms of input-referred noise and has a digitally-controlled gain between 36dB and 44dB. The amplifier is AC-coupled, with a pass-band from 0.3 Hz to 4.7kHz. The circuit is implemented in a 0.5 microm SOI Bi-CMOS process and consumes 805nA from a 1.0V supply, corresponding to a noise efficiency factor (NEF) of 1.8, which is the lowest reported NEF to date.