| Summary: | 碩士 === 國立中央大學 === 電機工程學系在職專班 === 104 === Abstract
In recent years, biomedical measurement instruments have been used commonly in daily life. In order to achieve micro-size and longtime wearing, high resolution and low power consumption are the necessary factors of analog to digital converter (ADC). The sigma-delta modulator (SDM) ADC for biomedical signals was implemented in this paper. Compared to other types of ADC, the specification of SDM is simple and high tolerance. The SDM ADC also significantly reduces the chip area and power consumption, thus we designed a second-order sigma-delta modulator using switched-capacitor circuits
This circuit was implemented in TSMC 0.18µm 1P6M CMOS process. With the signal bandwidth of 10 KHz and over-sampling ratio of 128, the signal to noise and distortion ratio (SNDR) can achieve 82.79 dB, 13.4 bits resolution, and power consumption is about 109 µW for 1.8 V power supply. The design will combine with the digital decimation filter to achieve mixed signal chip for sigma-delta analog to digital converter used in biomedical signal systems in the future.
Keywords: sigma-delta modulator, switched-capacitor circuits, analog to digital converter (ADC)
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