Patent ID: 6501775
Filing Date: 2002-12-31
Classification: H01S

Abstract:
A semiconductor laser driving circuit which drives a semiconductor laser in accordance with an input control current supplied from the outside, the device comprising:an input circuit configured to convert the input control current into a control current inside of an integrated circuit; a control amplification circuit configured to amplify a voltage corresponding to a difference current between the control current output from the input circuit and a monitor current corresponding to a light output of the semiconductor laser fed back from a photodetector for detecting the light output; an output circuit configured to supply a drive current to the semiconductor laser in correspondence to an output from the control amplification circuit; a first switch configured to interrupt the input control current to the input circuit; a second switch configured to cut off the output of the control amplification from an input of the output circuit; and an offset compensation circuit configured to detect an offset generated in a signal channel up to the output of the control amplification circuit from an input of the input circuit in the state in which the first switch is operated to interrupt the input control current to the input circuit while the second switch is operated to cut off the output of the control amplification circuit from the input of the output circuit, upon a drive instruction of the semiconductor laser being given and compensate for the offset on the basis of the detection result.