Full-Wave Digital Predistortion Linearization Based on Memory Polynomials for HF Power Amplifiers

Abstract

In order to suppress the intermodulation distortion and harmonic distortion caused by the nonlinearity of a HF power amplifier (PA), this paper presents a nonlinear correction method for full wave digital predistortion (DPD) of a HF PA based on a memory polynomial. First, the required full wave nonlinear signal is obtained by using the negative feedback iteration method for the digital predistorter, and then a full wave signal including the fundamental wave, each order harmonics and all intermodulation signals is constructed using the memory polynomial. Finally, the full wave memory polynomial model is constructed by shifting the spectrum of the same order connected harmonics and their adjacent intermodulation components. To verify the correctness of the method, the algorithm is simulated first, and then an actual PA is used to verify the experiment. A 5W short-wave PA is used to test and verify dual-tone signals at different carrier frequencies. The experimental results show that after linearization of full-wave DPD, the second and third harmonic components are improved by more than 35 dB, and the intermodulation distortion is improved by at least 9 dB, which effectively suppresses the intermodulation distortion and harmonic distortion.

Keywords

• Digital predistortion (DPD)
• full wave memory polynomial (FWMP)
• harmonic suppression
• linearization
• spectrum shifting