Optimum design of a new predistortion scheme for high linearity K-band MMIC power amplifiers

Abstract

A novel predistortion approach well suited for MMIC design is discussed. The theoretical analysis shows third-order intermodulation product (IMP3) cancellation independent of the specific technology exploited for implementation and of the detailed behaviour of the power stage nonlinearity; further improvements can be obtained through optimization. The active stages of the predistorter are modeled through a nonlinear describing function, which can be experimentally characterized through standard LS S-parameters measurements. The predistortion scheme has been implemented within the Agilent ADS environment and applied to the linearity optimization of a power amplifier stage. In accordance with theoretical results, significant improvement in the linearity of the Pin-Pout is demonstrated together with IMP3 reduction. A sensitivity analysis on the optimization parameters is also presented, showing that this approach is robust and well suited for circuit design.