An All-Digital ADC with Dynamic Sampling Technique for ECG Acquisition in Mobile Healthcare Applications

• Main Authors: Hsu, Pei-Yu, 徐佩妤
• Other Authors: Lee, Chen-Yi
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/76865519904756987969

碩士 === 國立交通大學 === 電子研究所 === 101 === Heart attack becomes the top cause of death in the U.S. in 2011. The preventive medicine of the heart disease becomes more and more important. To reduce the effort for people going to the hospital, the mobile healthcare device is applied to monitor the electrocardiogram (ECG) signal. Here we design a VCO-based ADC for the ECG acquisition circuit in mobile healthcare applications. The VCO-based ADC has high area efficiency and high integration ability with the digital circuit which are suitable for the mobile device. And also benefits from the technology scaling. Using 90-nm CMOS process technology, the ENOB of more than 8-bit VCO-based ADC is implemented. It can support both single channel and multi-channel ECG acquisition circuit application. For the single channel, the ENOB of ADC can reach 10.48 bits in sampling frequency of 1k Hz. The power consumption is 6.08 uW. For the multi-channel application, our design can operate in sampling frequency of 10k Hz and be turned off while sampling is finished. In the simulation result, the power of VCO-based ADC is 0.62uW/ channel for 8 channels application and achieves 9.64 bits of effective number of bit. To reduce the power consumption of our ADC, we apply the dynamic sampling technique to sense the variation of signal. Then we adjust the resolution of ADC based on the sensing result. This technique can reduce 53% power of ADC while keeping distortion less than 5%. Compare with other technique this work has best power reduction performance under the same distortion factor.