Power amplifier linearization with digital pre-distortion and crest factor reduction

Abstract

This paper investigates the use of crest factor reduction (CFR) as a cost-effective method of increasing output power and efficiency for power amplifiers (PAs) operating in conjunction with pre-distortion linearization system. Previous result indicated adjacent and alternate channel leakage ratio (ACLR) improvements of 10-12 dB were obtained from memoryless pre-distortion of a high power amplifier using a standard IS-95 signal with a peak-to-average ratio of approximately 9.6 dB. This paper investigates the effect of using CFR data in conjunction with the same digital pre-distortion platform. It was found that using CFR with pre-distortion allows for an increase of 2.7 dB in output power while maintaining the same ACLR of -45 dBc at 885 KHz offset on a 30W LDMOS PA. Furthermore, due to the decreased output back-off an effective efficiency improvement of 5.6% was also realized.