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Some Aspects of Efficiency and Linearity Improvement Techniques for Microwave GaAs HBT Power Amplifier.

Ali, Fazal. (2001) Some Aspects of Efficiency and Linearity Improvement Techniques for Microwave GaAs HBT Power Amplifier. Doctoral thesis, University of Surrey (United Kingdom)..

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This thesis examines some aspects of improving the power-added efficiency (PAE) and the third order inter-modulation distortion (IMD) performance of microwave GaAs HBT power amplifiers. The research encompasses analysis, computer-aided design and simulation and also includes investigation of the measured performance of some HBT power amplifiers. This then allows conclusions to be drawn as to the merits of the proposed techniques applied to GaAs HBT microwave power amplifier compared to the known published methods. High efficiency, Class C operation of microwave HBT power amplifier is described for the first time. A record PAE of 84% has been demonstrated for a 0.75-Watt HBT power amplifier operating at 6 GHz. Simulated and measured performance are presented and compared with the conventional high efficiency Class AB mode operation of HBT power amplifier. The third order IMD performance of a microwave HBT power amplifier is improved significantly by using the second harmonic injection technique. This is the first demonstration of this technique applied to a HBT microwave power amplifier. Mathematical analysis, CAD simulations and practical measurements have been carried out to show the feasibility of this technique. A record 46 dB reduction in the third order IMD product has been achieved from a two-stage, 28 dBm HBT Power amplifier operating over the 824-849 MHz frequency band. The technique has also been successfully applied with FM, AM, and digitally modulated RF input signals.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Ali, Fazal.
Date : 2001
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2001.
Depositing User : EPrints Services
Date Deposited : 30 Apr 2019 08:08
Last Modified : 20 Aug 2019 15:33

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