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Title: Use of waveform engineering to stress test, characterise and design a highly efficient MMIC power amplifier
Author: Loescher, David
ISNI:       0000 0004 7651 6951
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2018
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This thesis brings together different areas of waveform engineering in power amplifier research, from load pull and reliability testing through to measuring finished designs. It shows how using all this knowledge together can enable an engineer to start with just a transistor, and progress to a functional design much faster with the use of waveform engineering at every stage. Initially this project looked at expanding the conventional voltage standing wave ratio sweep to address more than the fundamental impedance with static harmonic impedances by including full harmonic impedance sweeps. This showed there were voltage peaking interactions that could potentially cause device failure, these were caused by interactions between the fundamental and harmonic impedances. The next step was to identify the cause of failures that had occurred during voltage standing wave ratio sweeps. This demonstrated the need for waveforms to identify failures caused by peak voltage and/or current. Waveform data can also be used to analyse and compare the different device technologies and analyse their performance, allowing deep insight into the `knee' region of the RF-IV plot, and how it affects performance of a technology using a novel data processing approach. The final use of waveforms in this thesis is at the design stage, where a Continuous Class B design was done on a quasi-MMIC. This design was then fabricated and tested, showing that Continuous Class B and other continuous modes can be used for quasi-MMIC designs at S-band as well as the previously used laminate designs. Another topology that was used in this thesis was Doherty, which has traditionally struggled with bandwidth, but using a novel 50 V GaN FET supplied by Qorvo allowed a more broadband Doherty design to be fabricated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available