| Summary: | 碩士 === 元智大學 === 電機工程學系 === 92 === This paper presents a low-voltage/low-power MASH 1-1-1 sigma-delta modulator for voice band of 4KHz with a bandwidth of 8KHz. The modulator operates in a 1.8V power supply; the involved operational amplifiers dissipate only 56W. The OSR is 64, and area is 991um×991um. The modulator is implemented in TSMC035 2P4M process and the resulting resolution is about 8 bits.
The sigma-delta modulator uses oversampling and 1-bit quantization to achieve high resolution A/D conversion at a lower rate. The 1-bit quantizer’s output of the sigma-delta modulator is essentially of two values, and hence needs no extra adjustment during manufacturing. In the analog-to-digital converter, the integrator can be composed of operational amplifiers and switched capacitors, and in addition, a digital-to-analog converter is not required in the feedback path. Therefore, sigma-delta modulator features high performance, a small circuit scale, and the possibility of manufacturing. It employs the multistage noise shaping (MASH) modulation techniques without using higher order integrators.
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