A Delta-Sigma ADC Design for a Wearable ECG Application

The study proposed a switched-capacitor delta-sigma modulator with single-loop and third-order structures for wearable electrocardiogram acquisition device for low-power and high-precision applications. Several techniques, including chain of integrators with weighted feedforward structure, gain-enhanced current-mirror push-pull operational transconductance amplifier, and dynamic comparator with a set-reset latch are adopted to improve the signal-to-noise ratio (SNR) and reduce the power consumption. Simulation results shows that the SNR and the corresponding effective number of bits are 104.2 dB and 17.02 bits, respectively, which fulfill the requirements of an presented system. The circuit will be fabricated by the SMIC using a 0.18 μm general purpose process in the near future.