Design of Amplifier for Wearable Human ECG Sensor with Low Power and Low Noise

Abstract

Electrocardiograph (ECG) data is an important index to determine the human heart state, which helps diagnose heart disease in an early stage. Since the ECG signal is instantaneous, it is important to make the ECG signal collector wearable and have good battery life. The wearable ECG devices need to have certain properties like interference suppression ability of acquired signal, low power consumption, low noise, and high integration, putting forward crucial requirements for the design of the amplifier. To meet the properties, the front-end analog processing circuit with interface input buffer stage structure and post-amp structure was proposed here, which has the characteristics of small size, low power consumption, low input referred noise, fair common-mode rejection ratio, and high input impedance. Besides, as one of the industrial-grade circuit simulation software, LTspice was used to design the circuit structure and analyze the corresponding performance. According to the circuit design and simulation testing, it turned out that the circuit in this work can be quite simple, and all the performance indexes met the practical demands. The frequency range was 0.1Hz∼100Hz, the voltage was 1.2V, the differential gain was 40.37dB, the total integrated input-referred noise was 3.48uVrms, and the total power consumption was 1.75uW. In summary, our data indicate that the ECG device we design is small enough to be wearable and has low power consumption.