| 摘要 |
<P>PROBLEM TO BE SOLVED: To change the resistance value of a feedback resistor in accordance with a transmission rate without exchanging a preamplifier circuit when the transmission rate of a transmission system is changed. <P>SOLUTION: The preamplifier circuit includes: an amplifier circuit for converting, into a voltage signal, a current signal from a photodetector that converts an optical signal into the current signal; the feedback resistor for connecting an input and an output of the amplifier circuit; and a transmission rate/voltage conversion circuit for controlling the resistance value of the feedback resistor in accordance with the transmission rate of the voltage signal. It is preferable, in the transmission rate/voltage conversion circuit, to reduce the resistance value of the feedback resistor as the transmission rate of the voltage signal increases. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
