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Use of waveform engineering to stress test, characterise and design a highly efficient mmic power amplifier

Loescher, David 2018. Use of waveform engineering to stress test, characterise and design a highly efficient mmic power amplifier. PhD Thesis, Cardiff University.
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Abstract

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.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: MMIC Continuous Class-B; Waveform Engineering; VSWR; High Voltage HBT; 50 V GaN HEMT; Broadband Doherty.
Date of First Compliant Deposit: 1 November 2018
Last Modified: 01 Nov 2018 14:14
URI: http://orca.cf.ac.uk/id/eprint/116177

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