A Low-Power 0.7 $\mu {\rm V_{\rms}}$ 32-Channel Mixed-Signal Circuit for ECoG Recordings

Monitoring of electrocorticography signals using multi-electrode array creates new opportunities for neural prosthetic applications. In this paper, we present a 32-channel recording ASIC that provides low-noise amplification and analog filtering. It also includes a 12-bit analog-to-digital conversion function, and offers programmable output rates through a serial peripheralinterface (SPI). The targeted application is a remote-powered wireless implantable ECoG recording system. Each recording channel has a measured 0.7 $\mu {\rm V_{\rm \rms}}$ input-referred noise on a [0.5–300 Hz] bandwidth. The device was fabricated in a 0.35 $\mu{\rm m}$ complementary metal–oxide–semiconductor process for a total die area of 86 ${\hbox {mm}} ^{2}$ with an analog power consumption limited to 134 $\mu {\rm W}$ per channel.