Optical recording and reproducing device with normalization of servo control signal using switchable automatic gain control circuitry

摘要

The present invention discloses a control circuit. An AGC circuit has an input of an x input signal and a gain control amplifier has an input of a z input signal. A division operation of z/x is made by controlling the gain of the gain control amplifier by a gain control voltage issued from the AGC circuit. A division output signal is obtained from an output terminal of the gain control amplifier, and is usable for compensating focus error, tracking error or the like in an optical recording and reproducing apparatus which makes recording and reproducing by a light of laser light or the like. Also included is a switching circuit that allows offset voltages to be reduced.