Abstract
The dual-band recording of the local- field p otential (LFP, 0.1–200 Hz) and the spike potential (SP, 200 Hz–10 kHz) is important for physiological studies at the cellular level. Recent study shows that the LFP signal plays importan tr o l e si nm o d - ulating many profound cellular mechanisms. Although various bio-signal acquisition circuit s have been reported over the years, few designs are applicable to capture both L FP 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 in the LFP band, and a discrete-time (DT) back-end to achieve good linearity. The acquisition channel is fully differential, which leads to a high common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) without the 50 Hz injection. The design interfaces the microelectrode w ith a transistor gate, which has high input impedance. A prototyp e monolithic acquisition IC is fabricated in a 0.35 mC M O S process. It includes 16 channels and an 11 bit successive-approximation (SAR) analog-to-digital converter (ADC). Every channel acquires cellular signals up to 20 mV with 32.9 nV/Hz and % nonlinearity. The good linearity effectively prevents the aliasing and mixing between the two bands. For LFP signal, the recording noise is 0.9