An Ultra-Low-Power QRS-Detection System Based on Level-Crossing Sampling

A real-time QRS-detection algorithm is proposed which is working based on level-crossing sampling. Using level-crossing sampling leads to decreasing the number of useless samples, reducing the noise level and omitting the undesirable parts of the signal, and so a considerable decrease of the complexity of the algorithm and the power consumption of the processor. Also, the accuracy of the algorithm is increased by utilizing an automatic tuning circuit in order to adjust the algorithm parameters based on the signal characteristics. The proposed algorithm is implemented in 0.18 μm CMOS technology with a 1.8 V supply voltage. Consuming a 190 nW power and occupying a 0.046 mm²silicon area, the proposed system is suitable for portable ECG monitoring applications. By testing the proposed algorithm over all the 48 tapes of the MIT / BIH Arrhythmia Database, a sensitivity of 99.07%, a positive prediction of 99.47% and a detection error rate of 1.44% is resulted.