LIGHT RECEIVING AMPLIFIER CIRCUIT AND OPTICAL PICKUP

PROBLEM TO BE SOLVED: To reduce the error of an output voltage with respect to an input signal from a light receiving element in a light receiving amplifier circuit using a transistor as the switching element of a feedback circuit. SOLUTION: The light receiving amplifier circuit 1 is provided with a bias current source CSB1a. The collector current of a transistor SW1 becomes a current where a bias current IBIAS1a generated in the bias current source CSB1a is added to a current IPD1 flowing through the light receiving element PD1. Thus, since the collector current of the PNP transistor SW1 is increased, the amount of change in the impedance of the transistor SW1 is reduced. As a result, the error of an output voltage Vol with respect to an input signal from the light receiving element PD1 is reduced. COPYRIGHT: (C)2008,JPO&INPIT