Distortion compensation circuit including tunable phase path

摘要

A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and/or an optical fiber and may include a primary signal path for carrying an input signal and a secondary signal paths for generating distortion. The distortion compensation circuit may also include a controllable phase inverters and a tunable filter. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products and a tunable filter that adjusts the phase of the frequency dependent distortion. The phase inversion and tunable filter may be controlled in response to control signals generated based on one or more parameters such as, for example, laser power, input RF channel loading, temperature, and fiber length.

主权项

1. A distortion compensation circuit for compensation of distortion produced by at least one non-linear element, said distortion compensation circuit comprising:
a primary signal path configured to carry at least a portion of the magnitude of an input signal; a secondary signal path coupled to said primary signal path, said secondary signal path configured to receive at least a portion of said input signal, to generate distortion, and to add at least a portion of said generated distortion back into said primary signal path; a tunable filter located in said secondary signal path, said tunable filter configured to control the phase of said generated distortion in response to a phase adjustment control signal, wherein said tunable filter comprises: a varactor having adjustable capacitance to control the phase of said generated distortion in response to said phase adjustment control signal; and capacitors coupled in series with said varactor, said capacitors configured to block said phase adjustment control signal from extending beyond said tunable filter; and a signal controlled phase inverter located in said secondary signal path, said signal controlled phase inverter being configured to invert said phase of said signal on said secondary path in response to a phase inversion control signal.