Commercial SiGe and GaAs as low noise amplifiers (LNA) performance under electron radiation

Abstract

In this dissertation, a characterization and comparison between the effects of Electron irradiation on low noise amplifiers (LNAs) implemented in a Silicon-Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) and Gallium-Arsenide (GaAs) HBT technologies, respectively, was carried out. Nowadays, commercial on the shelves (COTS) LNAs have been used in CubeSat communication system lunched in Low and Medium Earth Orbits. It therefore believed that the electron radiation in space may degrade the LNAs performance and lead to it failure. This is shows the importance of such investigation in evaluating and comparing the performance of the GaAs and SiGe LNAs which represent an important module in the front end of the communication receiver system. Two samples of GaAs and SiGe have been selected: the SiGe BFU730F and the ADL 5523 GaAs LNAs which are respectively cover a frequency range of 2.3 to 2.7 GHz and 400MHz to 4 GHz. The SiGe BFU730F achieves a peak gain of 21.5 dB and a peak of 0.8 dB noise figure within the frequency range before radiation. While the ADL 5523 GaAs LNA achieves a peak gain of 21.5 at 900 MHz; and it achieves approximately 15 GHz of gain, with a noise figure (NF) of 0.9 dB in the interested band of 2.3 GHz. Samples were irradiated with 3 MeV Electron doses ranging from 50 kGy to 250 kGy. The results show the increase of the NF and the drop of the gain of both LNAs which indicate that both SiGe and GaAs HBT technologies have been affected by the electron Irradiation. However, the GaAs LNA exhibits to be robust with a minimal degradation compare with the SiGe LNA, where it can still achieve a peak gain of 12 dB and a mean of Noise figure below 3 dB. However, the SiGe degraded with a drop of the gain down up to 7 dB and an increase of the Noise Figure above 3 dB within the frequency range.