| 摘要 |
PROBLEM TO BE SOLVED: To increase the quantity of an output voltage changed from a logarithmic conversion type image sensor. SOLUTION: A photodetector has a photodiode generating an electric signal corresponding to the incident quantity of a light and a transistor for a logarithmic conversion logarithmically converting the voltage value of the electric signal. The transistor has a first electrode as one of a source electrode and a drain electrode, a second electrode as the other of the source electrode and the drain electrode and a gate electrode. The first electrode is connected to the photodiode. A specified voltage is applied to the second electrode so that the transistor for the logarithmic conversion is operated in a sub-threshold region. The photodetector further has a means for bringing the voltage of the gate electrode under a floating state when the transistor for the logarithmic conversion logarithmically converts the voltage value of the electric signal. COPYRIGHT: (C)2005,JPO&NCIPI
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