| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier capable of having a smaller chip for signal processing and a higher operation speed for processing output signals from a light receiving element, and coping with high frequency signals while maintaining frequency characteristics of the output signals from the light receiving element. SOLUTION: A current mirror circuit N1 comprising NPN transistors QN4 and QN5 is inserted between the light receiving element PD and a V-terminal of an IV conversion amplifier to invert an input current. Further, a current mirror circuit N3 comprising NPN transistors QN8 and QN9 is connected to a V+ terminal of the IV conversion amplifier to reduce an offset voltage of the IV conversion amplifier. A current mirror circuit P2 comprising PNP transistors QP1, QP2, QP3, QP6, and QP7 is connected to the current mirror circuit N1 and N3 as their current source. A collector current I0 for making the frequency characteristics of the transistors QN4 and QN5 nearly maximum is supplied to the current mirror circuit N1, and a collector current I0 for making the offset voltage of the IV conversion amplifier nearly minimum is supplied to the transistors QN8 and QN9 of the current mirror circuit N3. COPYRIGHT: (C)2004,JPO
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