A novel wide-band noise-parameter measurement method and its cryogenic application
The concept of using a long mismatched transmission line to measure noise parameters has been known for some time. However, it has been limited to narrow-bandwidth applications, and a wide-band extension has never been reported. In order to measure the cryogenic noise parameters of a wide-band low-noise amplifier (LNA), a wide-band frequency-variation method is proposed. In this method, the four noise parameters at each frequency are derived numerically from a set of matched and mismatched noise temperatures measured within a surrounding frequency-sampling window. By scanning this frequency-sampling window, noise parameters over a wide frequency range can be obtained. Since this approach can be easily incorporated into existing noise measurement systems, a tuner is not required, and the technique can be applied to a cryogenic amplifier. This paper details the theory, implementation, and verification of this new method. The measured noise parameters of a cryogenic wide-band LNA are presented.
Additional Information© 2004 IEEE. Manuscript received November 21, 2003; revised January 18, 2004. Author R. Hu thanks Prof. G. Rebeiz, The University of Michigan at Ann Arbor, Dr. M. Edgar, D. Miller, F. Rice, G. Chattopadhyay, J. Kooi, and Prof. J. Zmuidzinas, all of the California Institute of Technology, Pasadena, Dr. J. Ward, Jet Propulsion Laboratory (JPL), Pasadena, CA, and Dr. F. Lo, National Radio Astronomy Observatory (NRAO), Charlottesville, VA, for their support and encouragement.
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