| 摘要 |
PROBLEM TO BE SOLVED: To provide a current-amplifying comparator for suppressing offset current mΔoccurred at a current mirror circuit by amplifying a minute optical current through the use of a subthreshold area of a transistor. SOLUTION: The comparator comprises transistors M1-M5, wherein a source of the transistor M1 is connected to an electric voltage Vdd, sources of the transistors M2 and M4 are commonly connected to a gate of the transistor M1 to be driven by a constant current, a reference voltage Vref is supplied to a gate of the transistor M4 from the voltage Vdd. The comparator comprises a current mirror circuit in which a source of the transistor M3 is connected to a GND (ground) voltage, a drain and a gate of the transistor M3 are short- circuited to be connected to a drain of the transistor M2, the source and the gate of the transistor M3 are connected to a source and a gate of the transistor M5, and a drain of the transistor M5 is connected to a drain of the transistor M4 to output. Consequently, the transistor M1 operates in the substhreshold area. COPYRIGHT: (C)2003,JPO
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