Common-Mode Interference in Biopotential Amplifiers: Modeling, Analysis, and Design Strategies for Various Recording Setups

This review provides a comprehensive overview of techniques for mitigating common-mode interference (CMI) in biopotential analog front-ends (AFEs). The mechanisms of CMI generation in various biopotential measurement scenarios, including neurostimulation and two-electrode ECG, are modeled electrically. The impact of CMI on signal quality is analyzed from both small-signal and large-signal views, highlighting the scenario-dependent nature of the CMI issue. Techniques for improving the common-mode rejection ratio (CMRR) are introduced to suppress CMI in small-signal conditions. The concept of total CMRR (TCMRR), which incorporates the effect of asymmetric contact impedance, is reviewed, and corresponding design strategies for maximizing TCMRR are analyzed. In the large-signal view, CMI-induced distortion and approaches for enhancing tolerance CMI are discussed, addressing both sub-supply and over-supply CMI scenarios. By analyzing mitigation techniques across different measurement contexts, this review offers practical design insights to guide future biopotential AFE designers in selecting the most appropriate solutions.