... Gain Fluctuations of Cryogenic Amplifiers Abstract
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ALMA Memo # 560
Methods for the Characterization and Measurement of the Gain Fluctuations of Cryogenic Amplifiers
J. D. Gallego, I. Lopez, C. Diez, A. Barcia
2006-10-04
Since ALMA instrument will have low noise receivers with very large instantaneous bandwidth, gain stability should be carefully specified to avoid limiting the sensitivity of the total system. This memorandum reviews the methods for the characterization of gain stability in the time and frequency domain and presents examples of experimental setups used for its measurement in the case of cryogenic amplifiers of the type used in the IF of ALMA as well as its practical limitations. Special attention is paid to some important but not widely known effects, as the dependence of gain fluctuation with bias and its variation across the band of the amplifier. Finally, the compliance of one prototype 4-12 GHz InP cryogenic IF amplifier with the requirements of ALMA project is discussed.
View a pdf version of ALMA Memo #560.
