A Low-Noise and Low-Power Multi-Channel ECG AFE Based on Orthogonal Current-Reuse Amplifier

This paper proposes a low-noise and low-power current-reuse analog front-end (AFE) for multi-channel electro-cardiography (ECG) acquisition. A new low-power orthogonal recombination method is proposed in the four-channel current-reuse amplifier, which reduces the recombination current by half and cuts down the power supply voltage while ensuring the crosstalk suppression capability, resulting in a lower average channel power consumption. A four-order current-cancellation subthreshold-source-follower low-pass filter (CS-LPF) is proposed in this paper, which realizes the reduction of the chip area and power consumption by cross-coupling current cancellation technology. In addition, the input impedance boosting circuit, DC servo loop (DSL), and successive approximation register analog-to-digital converter (SAR-ADC) are designed in the proposed AFE, and it can record and quantify ECG signals. The presented AFE was implemented in a 65nm CMOS process, and the core area is 1.42mm x 0.85mm. The measured results show that the proposed AFE has a variable gain of 40.5-56dB. The fully differential low-pass filter with a power consumption of only 4.8nW achieves 50% capacitance reduction. The average power consumption per channel of the proposed AFE is only 2.6 mu W, and the power efficiency factor (PEF) and noise efficiency factor (NEF) are 3.93 and 1.81 respectively.