| Summary: | 碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 97 === In this paper, we use TSMC 0.35 μm 2P4M CMOS process to design an improved high-sensitivity spot position detector or so-called position sensing detector (PSD) chip. This chip has a photo-diode array composed of 19 × 19 pixels and each pixel size is 36.8 μm × 36.8 μm. The position sensitive detector can be used to detect the position of flash spot in the image sensor regardless of background light. In this chip, we design a new trans-impedance amplifier to convert the photo-current into voltage signal and then a bandpass filter is used to get the AC voltage signal with desired frequency. Finally, the AC signal is feed into a lock-in amplifier to perform high sensitivity detection. In order to improve performance for all amplifiers in the circuit, a rail-to-rail operational amplifier (OP) is used to have the maximum output swing. This OP can achieve a power ratio of more than 66%. The whole chip simulation show that the trans-resistor gain is 180 MΩ, the consumed power lower than 20 mW, and the positioning linearity is better than 90%.
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