432 nW per Channel 130 nV/rtHz ECG Acquisition Front End with Multifrequency Chopping

An ultralow-power low-noise analog front end (AFE) for ECG signal acquisition is demonstrated. The key to its performance is a multifrequency chopping technique that helps to significantly reduce power consumption by frequency-division multiplexing of two channels in a single low-noise instrumentation amplifier (IA). A complete two-channel AFE, chopped at frequencies of 4 and 8 kHz, is implemented in a 0.13-μm CMOS technology from United Microelectronics Corporation. A current-reuse technique is employed in the first stage of the IA to achieve area savings and improve interchannel isolation. Experimental results show that the front end achieves an input-referred noise voltage density of 130 nV/rtHz while consuming current of 360 nA per channel from a 1.2-V power supply. The 1/f noise corner of the system is around 10 Hz, and the measured common-mode rejection ratio (CMRR) is 98 dB.