A 400GΩ Input-Impedance, 220MV<inf>pp</inf> Linear-Input-Range, 2.8V<inf>pp</inf> CM-Interference-Tolerant Active Electrode for Non-Contact Capacitively Coupled ECG Acquisition

Abstract

This paper presents a purely capacitively coupled active electrode (AE) for ECG acquisition for implementation in smart clothing or furniture. The AE has a DC input impedance of 400GΩ and 3.7µV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</inf> (0.5-100Hz) input-referred noise. The whole design supports 220mV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</inf> differential linear input range required in practical scenarios. An active driven-right-leg (DRL) loop is provided, achieving at least 70dB CMRR for up to 2.8V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</inf> common-mode (CM) interference. Implemented in a 0.18µm CMOS process, the prototype occupies an area of 1.23mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and consumes 18µA and 13µA for the AE and DRL respectively. Through-clothing non-contact capacitively coupled ECG acquisition is demonstrated.