Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
2006-10-31
2008-09-23
Yam, Stephen (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S2140AG, C369S124120, C330S308000
Reexamination Certificate
active
07427738
ABSTRACT:
A light-receiving amplifier circuit of the present invention includes: a first preamplifier circuit to which a light-receiving element is connected; a second preamplifier circuit which is the same type as the first preamplifier circuit and which is apart from the light-receiving element; and a differential amplifier circuit for amplifying output voltage differential between the preamplifier circuits, wherein each of the first preamplifier circuit includes an amplifier and first and second plural feedback resistors, each of which resistors has an end commonly connected to an input terminal of the amplifier; an amplification factor of the differential amplifier circuit is less than one; and the first preamplifier circuit includes an output voltage expanding circuit which is connected to (i) another end of the first feedback resistors in the first preamplifier circuit and (ii) an output terminal of the amplifier, and which circuit is for expanding an output voltage range from the amplifier and supplying the expanded output voltage range to the differential amplifier circuit. This configuration provides a light-receiving circuit which is capable of reducing heat noise to prevent deterioration of the S/N ratio, while avoiding narrowing down of an output voltage range.
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patent: 2002/0175272 (2002-11-01), Shimizu
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patent: 2004120311 (2004-04-01), None
Morrison & Foerster / LLP
Sharp Kabushiki Kaisha
Yam Stephen
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