| Summary: | 碩士 === 國立臺灣大學 === 電子工程學研究所 === 101 === Aging population and growing chronic patients are becoming urgent things to be resolved. Patient-centered medical home is a solution to mitigate these impacts by the concepts of self-monitor, self-control, self-diagnosis, and self-treatment. In order to achieve these goals, convenient, flexible and portable circuit systems for bio-medical applications are researched popularly especially in the analog-to-digital converters (ADCs). Because ADCs are bridges of communication between the digital signal and the weak analog signal form nature world. This thesis presents a nano-Watt and 0.06mm2-ranked VCO-based delta-sigma modulator with sufficient resolution for portable bio-medical applications to achieve circuit requirements of convenient and flexible.
In the VCO-based delta-sigma modulator, the voltage scaling technique and center frequency self-calibration technique are proposed to achieve near 10 effective-number-of-bits (ENOB) without any additional amplifiers. In addition, the optimum supply voltage of the ring VCO is interpreted. This chip is fabricated in a 0.18μm CMOS process. The VCO-based delta-sigma modulator and center frequency self-calibration technique occupy an active area of 0.032mm2 and 0.028mm2 respectively and separately consume 379nW and 303nW. The self-calibration technique takes 120 sampling periods to correct the center frequency of the ring VCO from about 1.795MHz to 1.751MHz with -101.6dBc/Hz phase noise at 100kHz, which is within the range of 10 ENOB requirement. With an 885.01Hz 0.7Vpp-diff input signal, the modulator achieves peak signal-to-noise ratio (SNR) of 59.8dB and signal-to-noise plus distortion ratio (SNDR) of 58.5dB over bandwidth of 2kHz.
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