Design Methodology of Biopotential Amplifier with Adaptive CM Cancelling Technique

Abstract

In this paper, the specifications of the previous biopotential amplifiers are reviewed in terms of maximizing the SNR. Based on the analysis, it is found out that the most important requirement for maximizing the SNR is the robustness to common-mode interference. In order to enhance both tolerance to CMI and T-CMRR simultaneously, a common-mode charge-pump (CMCP) and adaptive CMI cancelling loop are proposed in our previous work, where CMCP absorbs displacement current from the CMI source and adaptive CMI cancelling loop minimize the CMI shown at the amplifier output, respectively. Especially, the paper presents an analysis of the adaptive common-mode cancellation technique using an LMS algorithm that is dedicated for removing 50/60Hz noise during the biopotential recording.