Patent ID: 6580675
Filing Date: 2003-06-17
Classification: G11B

Abstract:
A device, comprising:a laser to produce a laser beam whose power changes in response to a driving signal; a photodetector coupled to receive a portion of said laser beam to produce a detection signal indicative of said power; and a laser driver circuit to produce said driving signal to said laser, said laser driver circuit having a first signal source to produce a first portion of said driving signal, a second signal source to produce a second portion of said driving signal, and a control circuit to control said second signal source in response to said detection signal to maintain said second portion of said driving signal substantially constant when said first portion of said driving signal changes, wherein said control circuit includes an amplifier having a first input to receive a first input signal representing said first portion of said driving signal and a second input to receive a second input signal representing said detection signal, said amplifier operable to produce a control signal that controls said second signal source.