Patent attributes
The present invention has as an object to provide, for received-light amplifiers capable of changing the current-voltage conversion efficiency by changing the resistance of feedback resistors, a received-light amplifier which can prevent the deterioration of output voltage linearity occurring when the current-voltage conversion efficiency is low. The present invention includes: a light-receiving device PD; a current amplification circuit which amplifies an output current of the light-receiving device PD, and outputs the amplified current; and a current-voltage conversion circuit which performs voltage-conversion on the output current from the current amplification circuit. The current amplification circuit includes: an operational amplifier; a feedback resistor Rgn1 connected between an inverting input terminal and an output terminal of the operational amplifier; a feedback resistor Rgn2 connected in parallel to the feedback resistor Rgn1; a feedback resistor Rgp connected between a non-inverting input terminal and the output terminal of the operational amplifier; and a transistor switch SW3 inserted between the feedback resistor Rgn2 and one of the output terminal and the inverting input terminal of the operational amplifier.
