Patent ID: 7329851
Filing Date: 2008-02-12
Classification: G06F,H01L

Abstract:
1. A photodetector including a photosensitive region where pixels are arranged two-dimensionally; each pixel being constructed by arranging a plurality of photosensitive portions outputting respective electric currents corresponding to incident light intensities adjacent to each other within a single plane; photosensitive portions on one side out of the plurality of photosensitive portions constituting each of said pixels are electrically connected to each other across the plurality of pixels arrayed in a first direction in the two-dimensional array, photosensitive portions on another side out of the plurality of photosensitive portions constituting each of said pixels are electrically connected to each other across the plurality of pixels arrayed in a second direction in the two-dimensional array, the photodetector comprising: first integrating circuits which are provided correspond to groups of the photosensitive portions on one side which are electrically connected across the plurality of pixels arrayed in the first direction, convert corresponding electric currents from the groups of photosensitive portions on one side into voltages, and output the voltages; a first maximum value detecting circuit which detects a maximum value of the respective voltages outputted from the first integrating circuits; a first A/D converter circuit which converts the respective voltages outputted from the first integrating circuits into digital values within an A/D conversion range from the maximum value detected by the first maximum value detecting circuit to a value smaller than the maximum value by a predetermined value and outputting the digital values; a first level shift circuit which determines a voltage by subtracting a predetermined value from the maximum value detected by the first maximum value detecting circuit, subtracting thus determined voltage from the respective voltages outputted from the first integrating circuits, and outputs the resulting outputs to the first A/D converter circuit; second integrating circuits which are provided correspond to groups of the photosensitive portions on another side which are electrically connected across the plurality of pixels arrayed in the second direction, convert corresponding electric currents from the groups of photosensitive portions on another side into voltages, and output the voltages; a second maximum value detecting circuit for detecting a maximum value of the respective voltages outputted from the second integrating circuits; a second A/D converter circuit for converting the respective voltages outputted from the second integrating circuits into digital values within an A/D conversion range from the maximum value detected by the second maximum value detecting circuit to a value smaller than the maximum value by a predetermined value and outputting the digital values; and a second level shift circuit which determines a voltage by subtracting a predetermined value from the maximum value detected by the second maximum value detecting circuit, subtracting thus determined voltage from the respective voltages outputted from the second integrating circuits, and outputs the resulting outputs to the second A/D converter circuit.