Adaptive envelope shaping for low and medium power amplifiers with dynamic supply

This letter presents an adaptive envelope shaping (AES) method to linearize low and medium power amplifiers (PAs) with dynamic supply. This straightforward linearization solution results very useful for small cell or handset transmitters, where reducing power consumption and computational complexity of the digital part is crucial. With the AES method, there is no need of an a priori characterization of the PA to shape the supply voltage signal targeting maximum linearity. Excellent linearization results are obtained when the PA presents good AM-PM linearity, otherwise, additional phase distortion linearization has to be included to meet the ACLR specifications.This work was partially supported by the Spanish Government (MINECO) and FEDER under projects TEC2014-58341-C4-01-R and 03-R; by the Catalan Government under project 2014-SGR-1103; and by CATRENE under the project named CORTIF CA116

The digital predistorter goes multi-dimensional: DPD for concurrent multi-band envelope tracking and outphasing power amplifiers

Over at least the last two decades, digital predistortion (DPD) has become the most common and widespread solution to cope with the power amplifier's (PA's) inherent linearity-versus-efficiency tradeoff. When compared with other linearization techniques, such as Cartesian feedback or feedforward, DPD has proven able to adapt to the always-growing demands of technology: wider bandwidths, stringent spectrum masks, and reconfigurability. The principles of predistortion linearization (in its analog or digital forms) are straightforward, and the linearization subsystem precedes the PA (a nonlinear function in a digital signal processor in the case of DPD or nonlinear device in the case of analog predistortion and counteracts the nonlinear characteristic of the PA. Some excellent overviews on DPD can be found in [1]-[4]. Let us now look at the challenges that DPD linearization has faced and will continue to face in the near future with 5G new radio (5G-NR).This work has been supported in part by the Spanish Government and FEDER under MICINN projects TEC2017-83343-C4-1-R and TEC2017-83343-C4-2-R and by the Generalitat de Catalunya under Grant 2017 SGR 813

Digital predistortion linearization of a GaN HEMT push-pull power amplifier for cable applications with high fractional bandwidth

This paper presents two linearization strategies for a custom-designed wideband push-pull (PP) power amplifier (PA) for wired communication applications such as, for example, cable TV. Two digital predistortion (DPD) behavioral models are proposed to meet the in-band and out-of-band linearity requirements when efficiently amplifying wideband DOCSIS signals with high fractional bandwidth (FBW). A radiofrequency (RF) DPD linearizer based on a band-pass generalized memory polynomial (BP-GMP) behavioral model and a baseband (BB) I-Q DPD linearizer based on a harmonic distortion GMP (HD-GMP) behavioral model are proposed. Both DPD models take into account the harmonic distortion typical of high FBW amplification. Experimental results will show high efficient and linear amplification of a 4×192 MHz composite DOCSIS signal by properly combining a crest factor reduction (CFR) technique and the proposed DPD strategies.This work was supported in part by the Huawei Technologies and in part by MCIN/AEI/10.13039/50110001103 under Project PID2020-113832RB-C2