16-Channel High-CMRR Neural-Recording Amplifiers Using Common-Made-Tracking Power Supply Rails

Abstract

This paper presents a neural recording amplifier that operates in environments where large common-mode signals interfere. The proposed scheme employs two types of LDOs that generate isolated supply voltages and a buffer to sense a common-mode signal. Thanks to the isolated supply rails, both the intrinsic common-mode rejection ratio (ICMRR) and common-mode input impedance of the low-noise amplifier (LNA) are increased, which leads to the total common-mode rejection ratio (TCMRR) above 89.2 dB up to 1 kHz even in 16-channel recording with a shared reference electrode. Compared to the conventional method, the TCMRR is improved by 48.7 dB even for 28% mismatch of the electrode-tissue impedance (ETI) and 1% mismatch of the LNA input capacitances.