Abstract

Power amplifiers are at the heart of any high frequency communications network. Increasing the output power of amplifiers is conventionally carried out through 90-degree hybrids at frequencies above 3GHz and through 180-degree hybrids at lower frequencies. In this thesis, we go through the design, simulation, and prototype building and testing phases of a C-band, 47dBm solid-state microwave power amplifier and investigate its performance using the two types of hybrids. The device used is a Fujitsu device consisting of two independent transistors; each has a 10dB linear gain and a saturated output power of 44dBm. Three simulation packages were used in the design phase, ADS, a product of Hewlett-Packard, Zeland, a product of Zeland Software Inc, and Sonnet b, a product of Sonnet Software Inc. The results of tests revealed that, when a 180-degree hybrid was used, the amplifier exhibited better performance in terms of output power, power-added efficiency, and inter-modulation distortion. However, the amplifier utilizing a 90-degree hybrid exhibited better return loss results. The design, simulation, and testing of the amplifier were carried out at Fujitsu FCSI under the guidance and appreciated help of the applications lab engineering team.

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