A Compact, Low-Noise, Chopped Front-End for Peripheral Nerve Recording in 180 nm CMOS

This manuscript presents a compact, low-noise signal conditioning chain for peripheral nerve recording from implanted microelectrodes. Chopping is used in combination with switched capacitor techniques to reduce circuit noise and area while achieving accurate passband gain and corner frequencies. Time-windowed-integration sampling is used to eliminate aliased noise introduced by the discrete time circuits and ripple introduced by chopping. Gain and transfer function accuracy are maintained while taking advantage of open loop structures. The circuit achieves an input-referred noise of 1.44 µV
rms
while implementing 58 dB gain across a bandwidth of 476 Hz to 9.75 kHz, draws 36.8 µA from a 1.8 V supply voltage corresponding to 3.45 NEF and 21 PEF, and achieves 0.034 mm
²
area per channel, which is 8x smaller than state-of-the-art peripheral nerve recording circuits with similar noise levels.