An Eleven-Leads ECG recording SoC for Ultralow-Power Wearable Applications

This paper presents a 0.13-μm CMOS system-on-chip (SoC) designed for multilead ECG recording in low-power wearable applications. The fully integrated system features eight fully differential recording channels, capable of extracting 11 ECG leads, a fully differential 10-bit capacitive successive approximation register (SAR) analog-to-digital converter (ADC), a digital controller with a custom master SPI interface, low-dropout regulators (LDOs), and level shifters to facilitate integration. The ECG recording channels are implemented using a novel fully differential current mirror-based bioamplifier circuit, which offers tunable gain and intrinsic band-pass filtering. The bioamplifier achieves an input-referred noise of 1.8 μV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</inf> over a 0.3-500 Hz bandwidth, a total harmonic distortion (THD) of 0.234%, and consumes 4.24 μA. The ADC achieves an effective number of bits (ENOB) of 9.18 while consuming 11 μA. Overall, the SoC draws 347 μW from a 1.2-V supply and demonstrates successful 11-lead ECG recordings and PQRST wave identification.