An inline predistortion circuit for producing composite second order (CSO) and
composite triple beat (CTB) distortion correction of a laser transmitter is disclosed
having an RF input signal, a diode for producing nonlinear current, and a DC voltage
bias for controlling the nonlinear current. The predistortion circuit lacks DC
blocking capacitors between the RF attenuator and the diode, which results in improved
nonlinear current generation across a wide frequency range. A capacitor in parallel
with the bias circuit further increases diode's capability for producing nonlinear
current. A low resistance resistor in series with the RF signal path and in parallel
with the diode provides the voltage necessary for the diode to conduct while minimizing
RF signal attenuation. An inductor in series with the RF signal provides improved
phase correction of the CSO and CTB predistortion circuit. A temperature compensation
circuit is also integrated into the circuit to reduce the effect of temperature
variations on the correction circuit.