Abstract
Radio frequency (RF) power amplifier (PA) design using Gallium Nitride (GaN) transistor technology requires accurate device models in order to maximise performance and reduce development time. The current state-of-the-art frequency-domain behavioural models focus on linear and quadratic approximations to the polyharmonic distortion (PHD) formalism. However, the linear approximation suffers from poor accuracy under load mismatch conditions, while the quadratic approximation suffers from poor extrapolation beyond the measured range, leading to erroneous predictions of the optimum load impedances for maximum output power and maximum drain efficiency. In this work, a rational Padé-based approximation is proposed as the model core, and it is shown, through experimental validation, that the Padé approximation-based model can provide superior results in a more scalable format. It can mitigate problems found in the existing PHD models when applied to the matching problem. Specifically, the proposed model produces fewer erroneous solutions for the optimum load points, due to the well-behaved nature of Padé approximants. In addition, for the first time, results are reported on using the behavioural model to determine the optimum impedance for maximum transducer gain in a two-port device model. All results show the Padé model has high potential when compared to the established PHD-derived models in RF PA design.
Highlights
The cellular communication industry is a significant consumer market in the world today, with GSMA Intelligence estimating that the number of unique mobile subscribers worldwide is over 5 billion [1]
We demonstrate how the Padé model enables a more accurate prediction of the optimum load impedance for a given criterion, i.e. the impedance that maximises the desired metric
MEASUREMENT RESULTS USING PADÉ-BASED MODEL In order to investigate the real world efficacy of the proposed Padé-based modelling technique, loadpull-based waveform data is experimentally obtained from a 10W Gallium Nitride (GaN) device manufactured by CREE, CGH40010F
Summary
The cellular communication industry is a significant consumer market in the world today, with GSMA Intelligence estimating that the number of unique mobile subscribers worldwide is over 5 billion [1]. One way of mitigating this issue is to return to the standard X -parameter model in (3) We see it is effectively a first-order two dimensional Taylor series approximation to the describing function Fik. Previous work has shown that this linear polynomial can be modified to include higher order terms e.g. a quadratic model [12]. We build on previous modelling efforts [18]–[20] using Padé approximants, rather than polynomials, for simplification of the describing functions Fik. For the first time, we show the Padé-based model can provide significant advantages compared with the state-of-the-art when solving, numerically, the large-signal matching problem. The rational nature of the approximation allows higher order models to be considered when it is necessary to model, accurately, complex device behaviour This is, in general, not possible using poorly-behaved polynomial functions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
