Modulated rapid load pull system for the emulation of envelope tracking power amplifiers

Alsahali, S., Gecan, D., Alt, A. ORCID: https://orcid.org/0000-0002-7621-4940, Chen, P., Woodington, S., Sheikh, A., Tasker, P. ORCID: https://orcid.org/0000-0002-6760-7830 and Lees, J. ORCID: https://orcid.org/0000-0002-6217-7552 2020. Modulated rapid load pull system for the emulation of envelope tracking power amplifiers. Electronics Letters 56 (7) , pp. 325-328. 10.1049/el.2019.3896

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Abstract

This Letter presents a novel characterisation system that is able to fully emulate a complete envelope tracking power amplifier (ET-PA) environment, with modulated impedance synthesis and dynamic supply voltage generation while using industry-standard modulated signals and digital pre-distortion. The system is used to characterise a 10 W GaN device and provide impedance control over the signal and distortion bandwidths, in response to a 10 MHz long-term evolution signal. A National Instruments PXI-based measurement system is utilised to apply tracking signals to a bespoke supply modulator and successfully improve the average power added efficiency by ~18 percentage points. Three different shaping functions are implemented, and their efficiency and linearity performance evaluated. In addition, digital pre-distortion (DPD) is used to linearise the PA while operating with the three different tracking trajectories. Experimental results demonstrate that when applying shaping functions, a trade-off needs to be made between efficiency and linearity. Even though a constant gain shaping function provides lower efficiency, it achieves good raw linearity performance without DPD, which is a good option if local linearisation is not available. This novel system is a useful tool in the design of ET-PAs, to more completely investigate the performance of the device.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering
Publisher:	Institution of Engineering and Technology (IET)
ISSN:	0013-5194
Last Modified:	05 Jan 2024 08:28
URI:	https://orca.cardiff.ac.uk/id/eprint/132151

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