Power and efficiency enhancement of 3G multicarrier amplifiers using digital signal processing with experimental validation

This paper proposes a digital signal-processing-based approach suitable for the performance optimization of third-generation (3G) amplifiers in terms of spectrum and power. A peak-to-average power ratio (PAPR) reduction method, which is coding and modulation independent, based on peak clipping and digital filtering techniques, is proposed. Moreover, the multibranch memory polynomial pre-distorter identified with an optimized recursive least square technique was efficiently implemented in a digital signal processor. The cascade of the proposed PAPR reduction technique with the memory pre-distorter results in a substantial enhancement of the power amplifier (PA) output linear power and efficiency, while still meeting the 3G partnership project standard requirements. An experimental validation carried out on a 90-W laterally diffused metal-oxide-semiconductor PA, which was fed with a wide-band code-division multiple-access signal, led to a 4-dB rise in output mean linear power accompanied with 60% increase in its power-added efficiency.