| Summary: | 碩士 === 國立成功大學 === 電機工程學系碩博士班 === 95 === Digital pixel sensor(DPS) has grown quickly in recent five or six years. Beside the advantage of high speed operation, it shows excellent performance on noise elimination and dynamic range promotion. More and more scholars devote themselves to this area of DPS. However, the large pixel circuits of DPS also bring some problems. When more and more transistors are implemented into pixel circuit, the photodiodes may influence by the noise induced by transistors’ operation much more seriously. For this reason, my topic is studying on the effect induced by pixel circuits upon pixel outputs and photodiodes.
A DPS chip with noise testing capability is fabricated in TSMC 0.18μm 1P6M 1.8V mixed-mode process. Chip occupies the area of 1.253×1.253 mm² and pixel array is 60×60. Pixel level ADC’s resolution and conversion time are individual 8-bits and 10.24μs. The maximum frame rate the DPS chip can achieve is 12207 frames/s. Except DPS circuits, the active pixel sensor(APS) circuits are added in pixels to sample the photodiodes’ voltage directly. Then the analog signals are sampled by CDS circuits and column-to-column FPN is eliminated. This two parts of digital and analog work independently, hence the analog outputs can be observed under different operating frequency of DPS circuits. By measuring the analog output results obtained under different testing, the intensity of interference to DPS’s photodiodes will be detected and analyzing when pixel circuits are working.
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