12 May 2003 Shot noise reduction in the AlGaAs/GaAs- and InGaP/GaAs-based HBTs
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Proceedings Volume 5113, Noise in Devices and Circuits; (2003) https://doi.org/10.1117/12.490187
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States
Abstract
Noise parameters of AlGaAs/GaAs and InGaP/GaAs HBTs were measured in microwave frequency range and modeled using the small-signal equivalent circuit approach. Correlated current noise sources in the base and collector currents with thermal noise in the circuit resistive elements were accounted for by the model and yielded good agreement with the measured data. This enabled an extraction of the different noise source contributions to minimum noise figure (NFmin) in AlGaAs/GaAs and InGaP/GaAs HBTs. Decomposition of the (NFmin) in to the different contributors showed that the main noise sources in investigated HBTs are correlated base and collector current shot noise. The observed minimum of NFmin versus frequency at lower collector current is explained by the reduction of the emitter/base junction shot noise component due to the spike in the emitter/base junction and associated accumulation of the quasi-thermalized electrons forming a space charge, which screens the electron transfer through the barrier. The bias (VCE) increase creates an efficient electric field in collector/base junction, capable of 'washing out' the accumulated charge. Such shot noise reduction in HBTs could be exploited in the LNA for the RF application.
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Paulius Sakalas, Michael Schroeter, Peter Zampardi, Herbert Zirath, "Shot noise reduction in the AlGaAs/GaAs- and InGaP/GaAs-based HBTs", Proc. SPIE 5113, Noise in Devices and Circuits, (12 May 2003); doi: 10.1117/12.490187; https://doi.org/10.1117/12.490187
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