A Voltammetry Potentiostat Based on a Successive-Approximation ADC for Biosensor Applications

• Main Authors: Shang-HengShih, 施尚亨
• Other Authors: Bin-Da Liu
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/85938623804570089744

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 101 === This thesis presents a mechanism of sensing current for voltammetry potentiostat, and implements a sensing current circuit of potentiostat. By using a high efficient successive-approximation ADC and the improvements of sampling mechanisms, the wide dynamic range of sensing current capability can be obtained. To achieve the feature of low power, the circuit is designed with low supply voltage. In the thesis, the resolution is 10-bit and the main supply voltage is merely 0.6 V. The sampling capacitors of the circuit are shared between SAR ADC and current detector. Besides, current detector and clock generator control internal operation frequency with a proposed multi-sampling method for the enhancement of the current sensing range. Moreover, in order to improve the problem of sampling iota and the linearity of the sampling switch, a level shifting technique is used. The proposed sensing current circuit is implemented in TSMC 0.18-μm 1P6M CMOS technology. Under 50-kHz input signal bandwidth and 0.6-V power supply, the simulated peak SNDR achieves 60.03 dB with only 1.26-μW power consumption and the current sensing range is 5 fA to 2.1 µA. Besides, the measured peak SNDR achieves 56.28 dB.