No description available.

No description available.

The Ebers-Moll model, which is applicable to static or quasi-static conditions, is used as a basis for developing a simple method for the evaluation of harmonic distortion generated in bipolar transistor amplifiers. The Ebers-Moll equations are transformed into the desired forms using a Maclaurin Series expansion. A computer program is written to provide numerical results of the method, and these prediction are compared to measured distortion values.

Existing linearisation methods were examined to establish the requirements for a wideband power amplifier model. A range of memoryless models were investigated, in particular polynomial models. No suitable memoryless models were found. The shortcomings of the models were analysed and directions for future investigations presented. / thesis (MEng(ElectronicsEngineering))--University of South Australia, 2003.

Modern communication systems operate with high peak-to-average-power ratio (PAPR) over wide bandwidth. Linearity requirements force operation in a low efficient highly linear back-off region. Then increasing efficiency is becoming critical. One of the most promising technologies to accomplish this is using supply modulation, e.g. envelope tracking (ET) and envelope elimination and restoration (EER). Supply modulated systems have been studied extensively in the past years, but no systems have been presented with flexibility in the envelope amplifier circuit.   In this work the supply modulator amplifiers have been studied. The focus is on hybrid switching amplifier (HSA) as envelope amplifier. Two envelope amplifier prototypes P-I and P-II have been designed. They are both designed for 15W output but P-II has 28V maximum supply voltage and P-I has 15V maximum supply voltage. P-II developed in version A, using silicon (Si) based switching transistor and version B using gallium-nitride (GaN) switching transistor. The efficiency is limited to a maximum 97 % possible by the circuit components.   The linearity was mainly analyzed by AM-AM diagrams. P-I, P-IIA and P-IIB, were analyzed in simulations and measurements. Results show high possibility of improvement with digital processing, i.e. digital pre-distortion (DPD). Linearization will improve the overall performance in the supply modulator (SM) systems, improving the delay issues and distortion produced by the implementation of the system.   The developed flexible board has made it possible to investigate alternative technologies of ET, focused in the hybrid switching amplifier (HSA). This has given the possibility to compare the overall performance for a traditional Si based switch with the novel Ferdinand Braun Institute’s (FBH) GaN-HEMT based switch with regards to bandwidth, efficiency and non-linearities introduced by the envelope tracking amplifier. P-I and P-II show high efficiency (> 60%) in results. For signals with adequate average power levels the efficiency is high, with around 70% efficiency for WCDMA signals. Phase distortions are evident already at a 5 MHz bandwidth.

No description available.

No description available.

Existing linearisation methods were examined to establish the requirements for a wideband power amplifier model. A range of memoryless models were investigated, in particular polynomial models. No suitable memoryless models were found. The shortcomings of the models were analysed and directions for future investigations presented. / Thesis (MEng(ElectronicsEngineering))--University of South Australia, 2003

Existing linearisation methods were examined to establish the requirements for a wideband power amplifier model. A range of memoryless models were investigated, in particular polynomial models. No suitable memoryless models were found. The shortcomings of the models were analysed and directions for future investigations presented. / thesis (MEng(ElectronicsEngineering))--University of South Australia, 2003.

Existing linearisation methods were examined to establish the requirements for a wideband power amplifier model. A range of memoryless models were investigated, in particular polynomial models. No suitable memoryless models were found. The shortcomings of the models were analysed and directions for future investigations presented. / Thesis (MEng(ElectronicsEngineering))--University of South Australia, 2003