Analysis of the input noise contribution in the noise temperature measurements

Shu-I Hu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In measuring the noise temperature of a cryogenic microwave low-noise amplifier (LNA), the noise from the input thermal buffer, i.e., the coaxial cable that connects the noise source to the amplifier, needs to be correctly accounted for. With the amplifier's noise temperature approaching just a few Kelvins, the postulate used in calculating the cable's noise temperature, that the cable is homogeneous and has a linear temperature profile, commands a further inspection. This letter analyzes these assumptions and clarifies the situations in which they hold. To substantiate this Kelvin-level discretion, a LNA is designed and measured.

Original languageEnglish
Pages (from-to)141-143
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number3
StatePublished - 1 Mar 2005


  • Noise temperature measurement

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