近幾年越來越多微機電感測器被應用於消費性電子產品上，而感測器開發研究又以電容式感測器最為普遍，當電容式感測器與讀出電路整合在單一晶片上時，由於電容式感測器的電容變化量相當小，所以讀出電路的設計就非常重要。
本論文利用積分三角調變器當作一個電容數位轉換器也是一個類比數位轉換器。模擬結果最小可偵測的電容為0.1fF以及訊號對雜訊與失真比可達73dB。整體面積包含I/O PAD為0.384 mm2並實現於CMOS 0.18um製程，在1.2V的操作電壓下消耗功率為0.29mW，適合於可攜式產品之應用。

In recent years, more and more MEMS sensors, especially the capacitive sensors, were used in consumer electronic products. The capacitive sensors have gained an increasing research interest in the last few years. The variance values of the capacitance are generally small, when the sensor and readout circuit are integrated together as a system on a chip (SoC). Therefore, the design of readout circuits are becoming more and more critical.

The proposed sensing circuit for capacitive sensors is based on sigma-delta modulator (SDM) and can be used not only as a capacitance-to-digital convertor (CDC) but also as a analog-to-digital (ADC). The simulated results showed that the minimum detectable capacitance value and the peak SNDR are 0.1 fF and 73 dB, respectively. The chip was implemented using CMOS 0.18□m technology and occupies an area of 0.384 mm2, including I/O pads. The power dissipation is only 0.29 mW under 1.2 V voltage supply. This low power circuit is suitable for the use in portable products.

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