A Multichannel Integrated Circuit for Electrical Recording of Neural Activity, With Independent Channel Programmability

Since a few decades, micro-fabricated neural probes are being used, together with microelectronic interfaces, to get more insight in the activity of neuronal networks. The need for higher temporal and spatial recording resolutions imposes new challenges on the design of integrated neural interfaces with respect to power consumption, data handling and versatility. In this paper, we present an integrated acquisition system for in vitro and in vivo recording of neural activity. The ASIC consists of 16 low-noise, fully-differential input channels with independent programmability of its amplification (from 100 to 6000 V/V) and filtering (1–6000 Hz range) capabilities. Each channel is AC-coupled and implements a fourth-order band-pass filter in order to steeply attenuate out-of-band noise and DC input offsets. The system achieves an input-referred noise density of 37
${\rm nV}/\sqrt {\rm Hz}$
, a NEF of 5.1, a
${\rm CMRR} > 60~{\rm dB}$
, a
${\rm THD} < 1\%$
and a sampling rate of 30 kS/s per channel, while consuming a maximum of 70
$\mu {\rm A}$
per channel from a single 3.3 V. The ASIC was implemented in a 0.35
$\mu {\rm m}$
CMOS technology and has a total area of 5.6
$\,\times \,$
4.5
${\rm mm}^{2}$
. The recording system was successfully validated in in vitro and in vivo experiments, achieving simultaneous multichannel recordings of cell activity with satisfactory signal-to-noise ratios.