An Integrated Cancelling Method of Harmonic and Intermodulation Distortion of Short-Wave Power Amplifier Based on Digital Predistortion

Abstract

When using short-wave power amplifiers (PAs) for long-distance communication, the output of the amplifier will have a series of in-band and out-of-band spectral interference problems introduced by harmonic distortion and intermodulation distortion (IMD) because of the nonlinearity and memory effect of the amplifier. The existing harmonic cancellation methods include the use of filter banks for harmonic cancellation and digital harmonic cancellation, but these methods will either increase additional hardware resources or only work for harmonic cancellation, neglecting intermodulation. Based on the analysis of the Volterra series, the harmonic cancellation memory polynomial (HCMP) model is proposed. Experimental results show that at the same model complexity, compared with GMP model, the HCMP model has improved the harmonic cancellation ability at different frequency points, in which the second harmonic improved by about 8 dB and the third harmonic improved by more than 12 dB. Meanwhile, the IMD5 and IMD7 cancellation performance of the HCMP model is about 1.6 and 4 dB better than that of the GMP model.