Digitally assisted neural recording and spike detection multichannel integrated circuit designed in 180 nm CMOS technology

This paper presents design and measurement results of an integrated circuit dedicated to recording and detecting a wide range of biomedical signals. The chip is designed in 180 nm CMOS technology and occupies 1.5×1.5 mm2. It consists of 8 channels responsible for amplification, filtration and detection of biomedical signals. In order to satisfy the requirements of a wide range of neurobiological experiments, the main parameters of a single recording channel, such as voltage gain, frequency band, voltage offset and threshold detection, are controlled independently by on-chip digital registers. The recording part is divided into two separate channels, i.e. an Action Potential (AP) stage and a Local Field Potential (LFP) stage. The voltage gain of the AP and LFP stages can be switched between 55.7/50.3 dB and 50.3/45.1 dB respectively. Corner frequencies of a particular stage can be digitally controlled in a wide range, i.e. the upper cut-off frequency can be changed in the 20 Hz–2 kHz (LFP stage) while the lower cut-off frequency can be tuned at the 120 mHz–3 kHz (LFP and AP stage). The upper cut-off frequency of the AP stage is equal to 6.9 kHz. In addition, the area of the analog part of the recording channel is 0.04 mm2. A single recording channel is supplied from ±0.9 V and consumes about 4.8 µW of power while the Input Referred Noise is equal to 6.2 µV resulting in 4.92 of Noise Efficiency Factor (NEF).