Design and Performance Evaluation of Ultra-Low-Power Analog Front-End Circuits for Next-Generation Wearable Healthcare Devices

Abstract

The rapid evolution of continuous personalized healthcare monitoring and long-term point-of-care medical diagnostic systems demands ultra-low-power (ULP) Analog Front-End (AFE) integrated circuits capable of extracting microvolt-level biopotential signals in the presence of severe motion artifacts, ambient electromagnetic interference, and dynamic baseline wander. Wearable biomedical platforms, such as continuous electrocardiogram (ECG), electroencephalogram (EEG), and electromyogram (EMG) patch monitors, are heavily constrained by battery capacities, requiring sub microwatt power consumption to enable battery-less or multi-week operational lifespans. This paper presents a comprehensive review and performance evaluation of state-of-the-art AFE architectures, topologies, and circuit-level techniques designed for wearable healthcare applications. We systematically analyze low-noise amplifier (LNA) structures—including capacitive-coupled operational transconductance amplifiers (OTAs), chopper stabilized architectures, inverter-based current-reuse amplifiers, and subthreshold bulk-driven configurations—evaluating their trade-offs across Noise Efficiency Factor (NEF), Power Efficiency Factor (PEF), Common Mode Rejection Ratio (CMRR), Input Offset Voltage, and Dynamic Range (DR). Furthermore, this review examines sub-ranging and SAR-based Analog to-Digital Converters (ADCs) integrated within modern AFEs to establish complete bio-signal acquisition chains. Quantitative performance comparisons reveal that chopper-stabilized subthreshold current-reuse amplifiers achieve superior NEF (<2.1) and high CMRR (>110 dB) while operating under supply voltages as low as 0.5 V to 0.8 V. Finally, we highlight ongoing engineering challenges, such as motion artifact mitigation, adaptive DC offset cancellation, and multi-modal bio-signal sensing, presenting an actionable roadmap for future research in sub-microwatt biomedical SoC integration.

KEYWORDS: Analog Front-End (AFE), Ultra-Low-Power (ULP), Low-Noise Amplifier (LNA), Chopper Stabilization, Bio-potential Acquisition, Wearable Healthcare, Noise Efficiency Factor (NEF), Subthreshold CMOS.