A 1V 10-bit Low Power Successive Approximation Analog to Digital Converter for Biomedical Applications

• Main Authors: Yi-Hung Chen, 陳奕宏
• Other Authors: 周煌程
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/62025799883878961465

碩士 === 長庚大學 === 電子工程研究所 === 94 === In a biomedical signal processing system, an ADC is an important circuit that successively converts analog biomedical signals into digital data for next analysis and processing. However, the ADC operates continuously. The power consumption is a very important factor in ADC circuit design. A low power DAC suitable for biomedical signals is proposed in the ADC of this thesis. Through charge recycling technique in DAC circuit, the charge can be effectively reused to reduce power at the low input voltage. The circuit accuracy and resolution are very essential, because of the application to biomedical signals. In order to increase both accuracy and linearity, the complementary signal generator and the multi-stage offset cancellation circuit are incorporated. Besides, the comparator compares the input voltage and the DAC output reference voltage. The circuit achieves the 1 volt operation with a rail-to-rail input common range through the current driven bulk (CDB) technique to reduce threshold voltages. In this thesis, a 1V supply voltage ADC is obtained with average power 32.5uW. For applications to biomedical signals the average power consumption is further reduced 9%. The differential nonlinearity (DNL) and integral nonlinearity (INL) results are less than 0.25LSB and 0.45LSB, respectively. The signal to noise ratio is 58dB and the effective bit resolution is 9.4 bit.