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552 nW per channel 79 nV/rtHz ECG acquisition front-end with multi-frequency chopping

An ultra low power low noise analog front-end for ECG signal acquisition is demonstrated. Key to its performance is a multi-frequency chopping technique that helps to significantly reduce power consumption by frequency-division multiplexing of two channels in a single low noise instrumentation amplifier. A complete two-channel analog front-end, chopped at frequencies of 4 kHz and 8 kHz, is implemented in a 0.18 μm CMOS technology from UMC. A current reuse technique is employed in the first stage of the instrumentation amplifier to further improve efficiency. Simulation results show that the front-end achieves an input-referred noise voltage density of 79 nV/√Hz while consuming a current of 460 nA per channel from a 1.2 V power supply. The 1/f noise corner of the system is around 10 Hz and the CMRR of 138 dB.