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Design of a high efficiency S-band power amplifier for a Cubesat
Author(s)
Mugisho, Moise Safari
Date Issued
2016
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
In all radio frequency (RF) electronic communication systems, power amplifiers (PAs) are used to generate the final transmitted signal. Specifically, these PAs are used to increase the output power of the transmitted signal. The PA accomplishes this by converting the applied direct current (DC) power to the PA into RF power, while being driven by a RF input signal. The portion of DC power that is not converted into RF power is dissipated as heat. The power conversion mechanism that takes place in a PA is described by the power conversion efficiency (PE) and the power added efficiency (PAE).
A CubeSat is a small satellite in the shape of a 10 × 10 × 10 cm cube, weighing less than 1 kg and contains a RF electronic communication system which allows communication with the satellite. A CubeSat requires a PA with high PE in order to increase the lifetime of the on-board battery, facilitate thermal management on-board the satellite, increase system reliability, and reduce the size and manufacturing cost of the satellite. To maximize the theoretical PE of a RF PA, several design techniques and classes of operation were investigated, the basis of which lies in the fulfilment of the necessary and sufficient conditions for a maximum PE. A PA, which uses the Class-F-1 (inverse Class-F) mode of operation, fulfils the necessary and sufficient conditions for a maximum theoretical PE, and therefore presents itself as a good option for a high efficiency PA.
This thesis presents the design of a Class-F-1 PA, using the Cree CGH40010F GaN power active device. An optimum output matching network is used to terminate the drain of the GaN power active device with the required load impedances at the fundamental, 2nd and 3rd harmonic frequencies of operation. The designed PA delivers a maximum PE of 95 % at an operating frequency of 2.2 GHz, a maximum PAE of 82 % at an operating frequency of 2.2 GHz and a maximum output power of 40.6 dBm at an operating frequency of 2.2 GHz.
A CubeSat is a small satellite in the shape of a 10 × 10 × 10 cm cube, weighing less than 1 kg and contains a RF electronic communication system which allows communication with the satellite. A CubeSat requires a PA with high PE in order to increase the lifetime of the on-board battery, facilitate thermal management on-board the satellite, increase system reliability, and reduce the size and manufacturing cost of the satellite. To maximize the theoretical PE of a RF PA, several design techniques and classes of operation were investigated, the basis of which lies in the fulfilment of the necessary and sufficient conditions for a maximum PE. A PA, which uses the Class-F-1 (inverse Class-F) mode of operation, fulfils the necessary and sufficient conditions for a maximum theoretical PE, and therefore presents itself as a good option for a high efficiency PA.
This thesis presents the design of a Class-F-1 PA, using the Cree CGH40010F GaN power active device. An optimum output matching network is used to terminate the drain of the GaN power active device with the required load impedances at the fundamental, 2nd and 3rd harmonic frequencies of operation. The designed PA delivers a maximum PE of 95 % at an operating frequency of 2.2 GHz, a maximum PAE of 82 % at an operating frequency of 2.2 GHz and a maximum output power of 40.6 dBm at an operating frequency of 2.2 GHz.
Additional information
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
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Name
208037861-Mugisho-Moise-Safari-Mtech-Electrical-Engineering-Eng-2017.pdf
Description
Thesis
Size
2.79 MB
Format
Adobe PDF
Checksum
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