Low noise amplifier with active feedback structure for implantable neural recording

Abstract

A novel low-power, low-noise amplifier is described for biomedical and bioengineering brain neural recording applications. The bioamplifier achieves the best power-size tradeoff compared to the previous design. By means of a new active feedback configuration, the DC offset is rejected without the large capacitors. An active differentiator with an amplifier in the feedback path places a high-pass cutting frequency in the transfer function. The midband gain consists of the passive components, and is insensitive to the mismatch of process. The bioamplifier has been implemented in the 0.35-μm 2P4M CMOS process and occupies 0.052mm2 of die area. The current consumption of amplifier is 2 μA at ±1.5V supply. The bioamplifier achieves a midband gain of 42 dB and a -3 dB bandwidth from 13 Hz to 10.5 kHz.The input-referred noise is 5.7 μVrms corresponding to an NEF of 3.1. © IEICE 2013.