| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 102 === This thesis presents a mechanism of current sensing for biomedical applications. This work can be integrated with external biomedical system, and to meet the requirement of the specification, by using a current mirror with an automatic current range detection circuit to increase the current sensing range. A method of constant voltage current measurement is utilized, and applies a current conveyor to maintain the voltage at sensor terminal. Follow by a current-to-timer converter to process the current output from current mirror, and transfer the sensor current into time signal. Then apply a time-to-digital converter to obtain 10-bit digital code. Therefore, Current signal can be displayed in digital mode. The overall design focuses on reducing circuit complexity, effectively lessens layout area, miniaturization of the whole biosensor system can be realized. The proposed circuit is implemented in TSMC 0.18-μm 1P6M CMOS technology. The driven clock signal of circuit is 100 MHz with a supply voltage of 1.8 V. The power dissipation is approximate to 1.41 mW. The measured current range achieves from 20 µA to 1200 µA and has good linearity with average R-squared value of 0.9986.
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