| US 7,485,838 B2 | ||
| Semiconductor device comprising a photoelectric current amplifier | ||
| Kazuo Nishi, Yamanashi (Japan); Tatsuya Arao, Kanagawa (Japan); Atsushi Hirose, Kanagawa (Japan); Yuusuke Sugawara, Yamanashi (Japan); Naoto Kusumoto, Kanagawa (Japan); Daiki Yamada, Kanagawa (Japan); and Hidekazu Takahashi, Kanagawa (Japan) | ||
| Assigned to Semiconductor Energy Laboratory Co., Ltd., Kanagawa-ken (Japan) | ||
| Filed on Jul. 24, 2006, as Appl. No. 11/491,507. | ||
| Claims priority of application No. 2005-217757 (JP), filed on Jul. 27, 2005. | ||
| Prior Publication US 2007/0045672 A1, Mar. 01, 2007 | ||
| Int. Cl. H03F 3/08 (2006.01); H03F 3/04 (2006.01) | ||
| U.S. Cl. 250—214A [330/288; 330/308] | 10 Claims |
| 1. A semiconductor device comprising:
a photodiode comprising a photoelectric conversion layer;
a current amplifier circuit comprising a transistor; and
a switch between the photodiode and the current amplifier circuit,
wherein the photodiode and the current amplifier circuit are electrically connected to each other by the switch when intensity
of entering light into the photodiode is lower than predetermined intensity so that a photoelectric current is amplified by
the current amplifier circuit to be outputted, and
wherein the photodiode and at least a part of the current amplifier circuit are electrically disconnected by the switch when
intensity of entering light into the photodiode is higher than predetermined intensity so that a photoelectric current is
outputted with a reduced amplification factor.
|