Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Multiport Noise Characterization and Differential Amplifiers



James P. Randa


I address the issue of the definition and measurement of noise figure and parameters to characterize multiport devices, particularly differential amplifiers. A parameterization in terms of the noise matrix appears to be the most practical. The noise figure for a given output port is defined and related to the noise matrix and scattering parameters of the device. As an example, the case of a differential amplifier with reflectionless terminations is considered in detail. The noise figure, effective input temperature, and gains are related to the results of a series of hot-cold measurements, as in the familiar two-port case.
Proceedings Title
Tech Dig., Auto. RF Tech. Group Conf.
Conference Dates
June 15-16, 2000
Conference Location
Boston, MA


amplifier noise, differential amplifier, multiport amplifier, noise, noise figure, noise matrix, thermal noise


Randa, J. (2000), Multiport Noise Characterization and Differential Amplifiers, Tech Dig., Auto. RF Tech. Group Conf., Boston, MA, [online], (Accessed February 29, 2024)
Created June 1, 2000, Updated February 19, 2017