Patent ID: 6728276
Filing Date: 2004-04-27
Classification: H01S

Abstract:
An operational amplifier for controlling bias current in a laser diode, the operational amplifier comprising:a first stage including a differential amplifier receiving as input a reference voltage and a laser diode voltage and having a transconductance that increases exponentially as a difference between the reference voltage and the laser diode voltage increases, wherein said differential amplifier generates an output current based on the input, said laser diode voltage representing an optical output strength of a laser diode, said reference voltage corresponding to a desired magnitude of said laser diode voltage; a second stage including a capacitor, the second stage integrating the output current to generate a first output voltage; and a third stage including an output buffer, said third stage configured to receive as input the first output voltage to generate a second output voltage approximately equal to said first output voltage, said second output voltage controlling a bias current for the laser diode.