A Modified Band-Limited Digital Predistortion Technique for Broadband Power Amplifiers

In this letter, a modified band-limited digital predistortion (DPD) technique is proposed to improve the performance of the conventional band-limited DPD method in wideband systems. The power amplifier's (PA's) spectral regrowth outside the passband of bandpass filter is unable to be compensated using the traditional band-limited DPD. To increase the overall linearized bandwidth and reduce the requirement for feedback signal path, this new technique introduced two modules of full-band model extraction and coefficient iteration based on the conventional structures of band-limited DPD. It provides higher linearization performance and also reduces the sampling rate of analog-to-digital converter. The experimental results for 30-W Class F PA and 40-W GaN Doherty PA with 40-MHz orthogonal frequency division multiplexing signal and 60-MHz long-term evolution signal, respectively, have shown the superiority of the modified band-limited DPD.