A driver for a vertical-cavity surface emitting laser (VCSEL) is provided
that includes a bias current source, a modulation current source, and an
output tracking circuit. The bias current source is operable to generate
a bias current and an output voltage for the VCSEL and to generate a
replica output voltage. The modulation current source is coupled to the
bias current source by at least one switch and is operable to generate a
modulation current for the VCSEL when the switch is closed. The output
tracking circuit is coupled to the bias current source. The output
tracking circuit is operable to generate a feedback signal for the bias
current source based on the output voltage and the replica output
voltage. The bias current source is also operable to generate the output
voltage and the replica output voltage based on the feedback signal.