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Input Harmonic and Mixing Behavioural Model Analysis

Bell, James Joseph ORCID: 2014. Input Harmonic and Mixing Behavioural Model Analysis. PhD Thesis, Cardiff University.
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This thesis details the necessary evolutions to Cardiff University's HF measurement system and current CAD model implementation to allow for input second harmonic and mixing models to be measured, generated, and simulated. A coherent carrier distribution system was built to allow four Agilent PSGs to be trigger linked, thus enabling for the first time three harmonic active source- and load-pull measurements at X-band. Outdated CAD implementations of the Cardiff Model were made dynamic with the use of ADS' AEL. The move to a program controlled schematic population for the model allows for any type of model to be generated and input into ADS for simulation. The investigations into isolated input second harmonic models have yielded an optimal formulation augmentation that describes a quadratic magnitude and phase dependency. Furthermore, augmentations to the model formulation have to comprise of a model coefficient and its complex conjugate in order to maintain real port DC components. Any additional terms that describe higher than a cubic phase dependency are not recommended as average model accuracy plateaus, at 0.89%, from ABSTRACT IV the quartic terms onwards. Further model investigations into input and output harmonic mixing of coefficients has been detailed and shows that model coefficient mixing achieves better model accuracy, however, coefficient filtering is suggested to minimize model file sizes. Finally, exercising the modelling process from measurement to design, a generated source- and load-pull mixing model was used to simulate an extrinsic input second harmonic short circuit, an intrinsic input second harmonic short circuit, and input second harmonic impedance that half-rectified the input voltage waveform with Class-B output impedances. The tests were set up to see the impact of input second harmonic tuning on drain efficiency. Efficiencies of 77.31%, 78.72%, and 73.35% were observed for the respective cases, which are approximately a 10% efficiency improvement from measurements with no input second harmonic tuning. These results indicate that to obtain performances at X-band close to theory or comparable to performance at lower frequencies input waveform engineering is required.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords: Cardiff Model; Behavioral Modelling; Nonlinear; Transistor; Load-Pull; Simulation.
Date of First Compliant Deposit: 30 March 2016
Last Modified: 27 Oct 2022 09:01

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