| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the high frequency characteristics of a preamplifier used in an optical communication system. <P>SOLUTION: The preamplifier is provided with a preamplifier circuit 2 which converts the output current signal outputted from an optical receiving element 7 to a voltage signal, a reference bias voltage generation circuit 6 which generates a reference bias voltage being a voltage value outputted from the preamplifier circuit 2 in the case of absence of the output current signal, a differential amplifier circuit 3 which takes the output signal of the preamplifier circuit 2 and the reference bias voltage as the input signals, a current abstraction circuit 5 connected to an input end of the preamplifier circuit 2, and an abstracted current control circuit which is provided between the differential amplifier circuit 3 and the current abstraction circuit 5 and controls the current which the current abstraction circuit 5 should pull out, on the basis of two output voltage signal differences outputted from the differential amplifier circuit 3. <P>COPYRIGHT: (C)2004,JPO |
