A CMOS Microelectrode Array System With Reconfigurable Sub-Array Multiplexing Architecture Integrating 24,320 Electrodes and 380 Readout Channels

This article presents a CMOS microelectrode array (MEA) system with a reconfigurable sub-array multiplexing architecture using the time-division multiplexing (TDM) technique. The system consists of 24,320 TiN electrodes with 17.7 μm-pitch pixels and 380 column-parallel readout channels including a low-noise amplifier, a programmable gain amplifier, and a 10-b successive approximation register analog to digital converter. Readout channels are placed outside the pixel for high spatial resolution, and a flexible structure to acquire neural signals from electrodes selected by configuring in-pixel memory is realized. In this structure, a single channel can handle 8 to 32 electrodes, guaranteeing a temporal resolution from 5 kS/s to 20 kS/s for each electrode. A 128 × 190 MEA system was fabricated in a 110-nm CMOS process, and each readout channel consumes 81 μW at 1.5-V supply voltage featuring input-referred noise of 1.48 μV
_rms
without multiplexing and 5.4 μV
_rms
with multiplexing at the action-potential band (300 Hz–10 kHz).