A 38.6nV/Hz0.5 −59.6dB THD dual-band micro-electrode array signal acquisition IC

Cellular field potential includes local field potential (LFP, 0.1Hz∼200Hz) and spike potential (SP, 200Hz∼10kHz). SP signal has been the focus of physiological studies. Recent study shows that the LFP signal plays important roles in modulating many profound cellular mechanisms. Although many bio-signal acquisition circuits have been reported over the years, few designs are applicable for both LFP and SP signals. To record both signals accurately, acquisition circuits need low noise and good linearity in both bands. In this paper, we report the design of a dual-band acquisition IC for microelectrode array (MEA) recording. The novel design uses a continuous-time (CT) front-end with chopping to suppress the noise, and a discrete-time (DT) back-end to achieve good linearity. A prototype monolithic acquisition IC is fabricated in a 0.35um CMOS process. It has 16 acquisition channels and a 11bit successive-approximation (SAR) ADC. Every channel achieves 38.6nV/Hz
^0.5
noise and <0.1% nonlinearity. The good linearity effectively prevents the aliasing and mixing between the two bands. For LFP signal, the recording noise is 0.9V
rms
. For SP signal, the recording noise is 3.9uV
rms
. For MEA recording, the new design has high input impedance (320MΩ@ 1kHz). The fully differential design has high CMRR (>110dB) and PSRR (>110dB). NEF of the new design is 6.4. The IC is experimented with rat cardio-myocytes recording.