A low-noise integrated bioamplifier with active DC offset suppression

This paper describes a novel low-power, low-noise amplifier for 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 Chartered 0.35-¿m 2P4M CMOS process and occupies 0.022 mm
²
of chip area. The current consumption of amplifier is 2 ¿A at ±1.5 V supply. The bioamplifier achieves a midband gain of 46 dB and a -3 dB bandwidth from 13 Hz to 8.9 kHz. The input-referred noise is 5.7 ¿V
_rms
corresponding to an NEF of 3.1.