Patent ID: 8670675
Filing Date: 2014-03-11
Classification: H04B

Abstract:
1. An optical transmitter comprising: an RF signal input configured to provide an RF input signal; a predistortion circuit configured to receive the RF input signal and to generate a predistorted RF input signal, the predistortion circuit comprising a primary signal path configured to receive at least a portion of the RF input signal and a secondary signal path coupled to the primary signal path and configured to receive at least a portion of the input signal, the primary signal path including a configurable delay segment for delaying the RF signal carried on the primary signal path, the configurable delay segment being configurable in response to at least one control signal to provide different delay settings, and the secondary signal path including at least one distortion generator configured to produce intermodulation distortion products from the RF input signal on the secondary path, wherein the predistortion circuit is configured to combine the intermodulation distortion products on the secondary signal path with the delayed RF signal on the primary signal path to produce the predistorted RF input signal; a laser configured to receive the predistorted RF input signal and to generate a modulated optical output, wherein the predistorted RF input signal compensates for distortion generated by at least the laser; and a controller coupled to the predistortion circuit and configured to generate the at least one control signal, wherein the controller is configured to generate at least a first control signal in response to at least a first transmitter operation mode and to generate at least a second control signal in response to at least a second transmitter operation mode, wherein the configurable delay segment is responsive to the first and second control signals to provide at least first and second delay settings, respectively, and wherein the first and second transmitter operation modes provide different RF loading conditions.