Power amplifier characterization for multicarrier satellite links

Background
During the last decade, communication satellite system have been replacing the previous digital links with analog ones, multiple carriers are allocated in the transponder bandwidth what requires high linearity performance. Higher complex modulation methods than the typically used 8PSK and QPSK are desired for increasing channel efficiency. The frequency bands used for satellite systems are located in the L, S, V and Q bands. Still, the most used bands are in the C-band (4 – 6 GHz), Ku-band (12 – 14 GHz) and Ka-band (20 – 30 GHz).
Despite the dominant preference of GaAs circuits in the satellite industry, there are recent advances towards the inclusion of GaN amplifiers. GaN offers higher power capabilities in higher frequency bands where GaAs starts do degrade. However, the adoption of GaN devices has been delayed due to its dispersive effects caused by electron traps that affects the transistor performance.
Linear amplifiers characterization is commonly made by continuous wave and two-tone. However, for multicarrier satellite communications, the use of complex modulated signals will describe with more accuracy the capabilities and limitations of the devices. In this thesis 2 different GaAs and GaN MMIC amplifiers working at C-Band will be characterized using multicarrier modulated signals.

Objectives
Develop a test bench for multicarrier characterization of power amplifiers based on arbitrary waveform generator and Spectrum analyser/oscilloscope.
Compare C-band GaAs vs GaN MMIC linear amplifiers performance in multicarrier operation
Analyse the temperature effect on the linearity performance in both technologies.

Qualifications
Knowledge in microwave electronics, RF measurement techniques, signals and systems and Matlab. Knowledge of semiconductor device technology is a plus.

Supervisor: Oliver Silva oliver.silva@chalmers.se   
Examiner: Herbert Zirath herbert.zirath@chalmers.se

Published: Wed 18 Jan 2017. Modified: Thu 26 Oct 2017