This paper presents an integrated low-power analog front end (AFE) for simultaneously detecting electrocardiogram (ECG) and respiration rate (RR). A low-power low-noise preamplifier is designed to amplify both the ECG and RR signals. A current-driven passive mixer is used in the RR path to up-convert the RR signal so that the ECG signal can be filtered out. The modulated RR signal is then down-converted to baseband to be further amplified and detected. Quadrature (I and Q) drive signals for the mixers are generated on-chip from an external 20 kHz clock signal. The receiver is fabricated on the OnSemi 0.5 μm CMOS process. Both simulation and preliminary measurement results verify the functionality of this work. The overall gain for the ECG and RR signals are 40 dB and 70 dB respectively, and the circuit draws 6.2 μA from a 3 V power supply. To the best of the authors' knowledge, this is the first work in the literature that shows integrated RR and ECG signal detection with such low power consumption.
['Jifu Liang', 'Shixiong Li', 'Ali Nikoofard', 'Soumyajit Mandal']
A low-power receiver for simultaneous electrocardiogram and respiration rate detection