| Alsahali, S., Gecan, D., Alt, A., Chen, P., Woodington, S., Sheikh, A., Tasker, P. and Lees, J. 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 |
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: | Engineering |
| Publisher: | Institution of Engineering and Technology (IET) |
| ISSN: | 0013-5194 |
| Last Modified: | 25 May 2021 01:24 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/132151 |
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