Patent ID: 7248610

Claim:
A laser driver to drive a laser diode comprising: a diode driver receiving bias and modulation currents to control the laser diode for generating light signals; a power detector detecting the power of the light signals; a first extreme detector, coupled to the power detector, detecting a first extreme value of detected power; a second extreme detector, coupled to the power detector, detecting a second extreme value of detected power, wherein the first extreme value is either the maximum or minimum power of the light signals while the second extreme value is the other; and a current controller comprising: a bias current generator generating the bias current according to the first extreme value; and a modulation current generator generating the modulation current according to the difference between the first and second extreme values; wherein a first loop constituted by the bias current generator, diode driver, laser diode, power detector and first extreme detector confines the first extreme value to a first requirement and a second loop constituted by the modulation current generator, diode driver, laser diode, power detector, first extreme detector and second extreme detector confines the difference between the first and second extreme values to a second requirement.