Low-Noise Technologies

Publications

26-Nov-2014
Correction to the published paper "Unified Theory of Linear Noisy Two-Ports"

Prepublication accepted version (open access)

28-Feb-2014
Low-Noise Technologies Completes Noise Theory for Next-Generation Radio Telescope Design

01-Nov-2013
Landmark noise theory paper published in IEEE Trans. Microwave Theory & Techniques

Prepublication accepted version (open access)

08-Sep-2012
Low-Noise Amplifier Device Provides Sensitivity for Next-Generation Radio Telescopes

Features at a Glance

Amplifier Device

World's lowest noise amplifier
No 1/f-noise device limitation
Uncooled noise temperature 3 K at 1.4 GHz
Near quantum limit noise when cooled
Ideal for radio astronomy application

Measurement System

Precision noise measurement to quantum limit
Speed and accuracy for ultralow-noise devices
No cryogenics or cooled termination required
Superior to any instrument or "hot–cold" method
Low-noise research and device development

Noise Theory

First complete theory of linear noisy two-ports
New network noise invariants identified
Invariant equations relate all network properties
Noise correlation parameter for characterization
Cascade invariants from constituent device values
Insight into physical mechanisms and operation
Foundation for amplifier device and measurement

Advanced noise technology addressing critical aerospace & electronic systems, scientific measurement, radiometry, geoscience & remote sensing, radio astronomy, and more.

Ultralow-Noise Microwave Amplification
Our uncooled amplifier device is now world's lowest noise. It achieves 3 K noise temperature at 1.4 GHz frequency, for example. Conventional amplifiers must be cooled to 20 K physical temperature to achieve this level of performance. In addition, this device provides the same low noise temperature when operated as an active cold load.

The primary interest is for next-generation radio telescopes requiring ultimate receiver sensitivity, such as the future Square Kilometer Array or China's Five-hundred-meter Aperture Spherical Telescope. Read more »

Quantum-Limited Noise Measurement
Our noise measurement system achieves accuracy to the quantum limit—exceeding any radio astronomy or standards laboratory. Conventional noise measurement methods utilize thermal noise reference standards, typically at 295 K room temperature or 77 K liquid nitrogen temperature. These noise reference levels and associated uncertainties are much too great for measurement of amplifiers having noise temperature less than 5 K. Read more »

Unified Network Noise Theory
Very early, it was known that noise temperature does not define fundamental amplifier noise performance, since negative feedback can be applied to arbitrarily lower an amplifier's noise temperature. In the mid 1950s, Hermann Haus and Richard Adler realized the significance of noise temperature in the limit of high-gain cascade amplification and proceeded to identify the invariance of minimum cascade noise temperature. Their important result was published in Proceedings of the IRE, August 1958.

But what are the fundamental physical noise properties of an individual amplifier itself that are invariant? And why does noise temperature fail to define inherent amplifier noise performance?

Our recently published unified network noise theory answers these questions—and much more. It completes the theory of linear noisy two-ports, unsolved since the initial work of Haus and Adler. A complete two-port network noise theory is the foundation for development and understanding of the amplifier device and measurement system presented here. Download paper »