The paper – authored by Guatam Jindal, and co-authored by Dr Tommaso Cappello and Prof Kevin Morris – is his first acceptance into the top journal for the RF and microwave technology field.
The abstract for the paper is below:
"In this work, a digital predistortion (DPD) model for the linearization of RF power amplifiers (PAs) is presented. The model provides a linearized gain (DPD + PA) independent of the instantaneous transistor channel temperature within a predefined temperature window. Channel temperature variations due to varying ambient temperatures or changes in the signal probability density function (PDF) cause long-term memory effects, which results in dispersed (dynamic) AM/AM and AM/PM characteristics. The presented model is used to compensate for the memory effects due to self-heating and external temperature changes by estimating the transistor channel temperature through a linear single-pole Foster thermal network. The DPD model uses a first-order Taylor approximation to cancel out temperature-based nonlinearities. Gaussian pulses are used to extract the PA intrapulse gain at different temperatures without being affected by the signal PDF, thus allowing temperature- and signal-independent PA characterization. The model is validated from 20 ◦C to 80 ◦C and by considering a class-B 3.75-GHz 10-W gallium nitride (GaN)-on-SiC PA. The DPD performance is evaluated by considering the normalized root-mean-squared error (NRMSE), the output spectra, and adjacent channel power ratio (ACPR) with and without DPD for multiple signals bandwidths and peak to-average power ratio (PAPR) and finally compared with other approaches.”
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Following his acceptance, Guatam has participated in the students’ paper final at INMMIC 2022 at Cardiff University in which he presented his work to the delegates.
Gautam is a member of the CSN group and is pursuing his PhD degree funded by Toshiba Research Europe Ltd, Bristol. He received his BEng degree (Hons) in Electrical and Electronic Engineering from the University of Bristol in 2018.
His current research lies in low-complexity digital predistortion (DPD) for RF amplifiers and is looking to solve temperature-related issues. His research interests lie in nonlinear RF device modeling, GaN transistors, reliability concerns and linearization.