Low-Noise Analog Front-Ends for Wearable Health Monitors

Abstract

Wearable health monitors have gained significant attention due to their potential in continuous health monitoring and early disease detection. The performance of these devices heavily relies on the quality of the analog frontend (AFE) circuits, which are responsible for amplifying and conditioning bio-signals such as electrocardiogram (ECG), photoplethysmogram (PPG), and electromyography (EMG). Low-noise AFEs are crucial for accurate signal acquisition, especially in the presence of weak bio-signals and environmental noise.PubMed This paper presents an overview of recent advancements in low-noise AFE designs tailored for wearable health monitors. We discuss various design strategies, including chopper stabilization, dynamic biasing, and noise filtering techniques, aimed at minimizing input-referred noise while maintaining low power consumption. Additionally, we explore the integration of AFEs with digital signal processing units to enhance signal quality and enable real-time monitoring.MDPI+2PubMed+2 Experimental results from several state-of-the-art designs are reviewed, highlighting their performance in terms of noise efficiency factor (NEF), power consumption, and signal fidelity. For instance, a 4-μW AFE achieved a NEF of 2.4 with a noise level of 0.39 μVrms, demonstrating significant noise reduction compared to previous designs. Another design integrated a sub-Hz filter and automatic gain control, resulting in a low input-referred noise of 64.2 pA_rms and a high transimpedance gain of 142 dBΩ.PubMedPubMed The paper concludes by discussing the challenges and future directions in AFE design, emphasizing the need for further miniaturization, integration, and optimization to meet the demands of next-generation wearable health monitoring systems.PubMed+2PubMed+2