PHOTOELECTRIC CONVERSION CIRCUIT

PROBLEM TO BE SOLVED: To provide a photoelectric conversion circuit capable of raising a cut-off frequency while securing a high gain even if a parasitic capacity to a photodiode is large. SOLUTION: A PDIC 1 includes: a receiving signal generation means 2 having a photodiode PD for converting an optical signal to a current signal corresponding to its strength and a first constant current source I1 connected in parallel with the photodiode PD; an amplifying means 3 having an operational amplifier OP with a feedback resistance Rf which outputs the current signal by converting it to a voltage signal corresponding to the current signal and a second constant current source I2 which passes the same amount of current as the first constant current source I1 passes; and a transistor Q1, to one side of which a signal output node of the receiving signal generation means 2 is connected, and to the other side of which a signal input node of the amplifying means is connected which carries electricity from the other side to the one side according to the current signal from the receiving signal generation means 2, and works as a separation means for excluding the inclusion of impedance at the receiving signal generation means 2 side in a transfer function in the calculation of the amplification of the operational amplifier. COPYRIGHT: (C)2011,JPO&INPIT