Patent ID: 6879608

Claim:
A laser driver, comprising: a first differential drive circuit having an input, an output, and a supply node for receiving a supply voltage; a parallel RC circuit connected to the supply node for providing the supply voltage to the supply node; a common mode current setting source connected to the supply node for generating a common mode current through the parallel RC circuit; an amplifying circuit with an output and an input connected to the output of the first differential drive circuit; a second differential drive circuit having an input connected to the output of the amplifying circuit, a common emitter node, and an output node; a laser diode connected to the output node; a current bias source connected to the output node; amplifier means coupled to the emitter node and to the common mode current setting source for comparing a common mode voltage on the common emitter node with a reference voltage and adjusting the common mode current in response to the comparison in order to adjust a common mode voltage of the first differential circuit; and an RC time constant circuit connected to the emitter node; and the amplifier means having a first input connected to the RC time constant circuit and a second input for receiving the reference voltage.