Ultra-Low Power Non-Uniform SAR ADC based ECG detector for Early Detection of Cardiovascular Diseases

Cardiovascular diseases are a leading cause of death worldwide which motivates to design the smart wearable healthcare devices to monitor the condition of the heart in real time. In this paper, we present an analog front-end circuit to process the Electrocardiogram (ECG) signal which can be used to detect the R-R interval and other parameters of the ECG signal. The proposed circuit mainly consists of a non-uniform quantizer-based successive approximation register analog-to-digital converter (SAR-ADC). Due to the non-uniform quantization of the signal, the proposed circuit consumes very less power which is needed for wearable healthcare devices. The non-uniform quantizer is designed based on the non-uniform nature of the ECG signal and is implemented by modifying the SAR algorithm. The parasitic extracted netlist of the proposed analog front end is simulated in TSMC 65-nm process node at a supply voltage of 0.6V. It is found that our circuit consumes an average power of 167 nW at a supply voltage of 0.6V. It operates at 2 kS/s with a DNL/INL of 0.288/0.869 and 8 bits of resolution. It is tested with ECG data from the MIT-BIH Arrhythmia database. The non-uniform ADC presents a 29.09% reduction in power over a uniform SAR-ADC of the same resolution operating at the same supply voltage.