Full-Scale Integrated Microwave Photonic Predistortion Filter Chip Design

Abstract

The proliferation of the internet and related telecommunications systems worldwide in recent years has required an increase in the bandwidth available to transmit information through these systems. High power amplifiers are used to support this wide bandwidth processing, but must be linear to transmit signals accurately. At high frequencies, the amplifiers develop nonlinearities in the form of intermodular distortions, which can be corrected by several different linearization techniques.

Predistortion filtering, one of the linearization methods for high power amplifiers, works by adding nonlinearities to the high-frequency signal going through the amplifier that cancel out the nonlinearities generated by the amplifier itself. This results in a linear output and the continued fidelity of the signal. Electronic predistortion is limited to a narrow bandwidth, but using a photonic system for the process allows for wider bandwidth usage. However, photonic predistortion chips are limited by nonlinearities caused by memory effects in the system. The Laurentian photonic predistortion chip design is offered as a solution to this limitation, and neutralizes the memory effects by adding a time delay to the modulated output. The Laurentian chip also improves on the efficiency of previous predistortion chips by including an on-chip optical-electrical conversion.