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25 May 2004 Experimental results of gain fluctuations and noise in microwave low-noise cryogenic amplifiers
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Proceedings Volume 5470, Noise in Devices and Circuits II; (2004)
Event: Second International Symposium on Fluctuations and Noise, 2004, Maspalomas, Gran Canaria Island, Spain
Applications like radio astronomy and space communications require ultimate sensitivity and make use of very particular receivers with state-of-the-art devices. Usually the receivers are cooled at cryogenic temperatures to reduce the noise even further. Noise temperatures of only a few times the quantum limit can be obtained in these conditions. During the past decade, Indium Phosphide HEMTs have demonstrated the best noise performance at cryogenic temperatures in the microwave frequency range of all active semiconductor devices, together with extremely low power consumption. For certain applications noise is not the only factor affecting the sensitivity. For example, gain fluctuations may play a dominant role in wide band radiometers. Unfortunately some of the factors that have contributed to improve the noise temperature have degraded the gain fluctuations. The operation at cryogenic temperatures also increases the fluctuations. This paper describes the experimental results obtained at the Centro Astronomico de Yebes (CAY) in the development of wide band cryogenic amplifiers. Special attention is paid to the influence of the bias point in noise and gain fluctuations. InP HEMTs from different foundries were tested. The amplifiers developed will be used in the Herschel ESA mission radiometers and the Atacama Large Millimeter Array (ALMA) receivers.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Juan D Gallego, Isaac López-Fernández, Carmen Diez, and Alberto Barcia "Experimental results of gain fluctuations and noise in microwave low-noise cryogenic amplifiers", Proc. SPIE 5470, Noise in Devices and Circuits II, (25 May 2004);


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