| Summary: | 碩士 === 國立中正大學 === 電機工程所 === 95 === The photodiode operating at a reverse biased voltage can yield electrons and holes when the light is incident upon it. Additionally, while the reverse biased voltage exceeds the breakdown voltage, the numbers of the electrons and holes increase rapidly through ionizing. The operation of the photodiode biased by a voltage higher than the breakdown voltage is called the Geiger mode. Such operation mode can produce a large electric current. The experimental results show that the photodiode continuously operating at a high reverse biased voltage tends to breakdown easily. In order to avoid damage of the semiconductor components and instability of the circuit operation, two kinds of protection mechanisms are proposed: one is the forward biased mechanism and the other is the shorting mechanism. The experimental results demonstrate that these two protection mechanisms can slow down the breakdown tendency. In the image detection system, the real-time image capture is realized by means of the Time-of-Flight (TOF) way. The 850nm laser light source is employed to conduct the experiments on the CMOS photodiodes with various structures
The TSMC 0.35um CMOS technology is used to implement the pixel array, including 32x32 photodiodes, row/column decoders, shift register, controller, multiplexor, and Correlated-Double-Sampling (CDS) circuit. In a 3D image detection system, the real-time image capture is usually realized by means of the Time-of-Flight (TOF) manner. This 32x32 CMOS sensor array was fabricated and will be tested to verify our 3-D image detection system.
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