2017 Volume 14 Issue 20 Pages 20170865
This work presents an electrocardiogram (ECG) compression processor for wireless sensors with configurable data lossless and lossy compression. Lifting wavelet transforms of 9/7-M and 5/3 are employed for signal decomposition instead of traditional wavelet. A hybrid encoding scheme improves compression efficiency by encoding the higher scales of decomposed coefficients with modified embedded zero-tree wavelet (EZW) and the lowest scale with Huffman encoding. Besides, a transposable register matrix for coefficients buffering during EZW encoding lowers the processing frequency without extra register resource. Implemented in SMIC 40 nm CMOS process, the processor only takes a total gate count of 10.8 K with 92 nW power consumption under 0.5 V voltage and achieves a compression ratio of 2.71 for lossless compression and 14.9 for lossy compression with PRD of 0.39%.