Cooled integrated circuit amplifies with lowest noise performance to date
22 March 2013
An integrated amplifier with the lowest noise performance so far recorded offers new possibilities for detecting the faintest electromagnetic radiation.
Last year, Chalmers University of Technology, Sweden reported a world record for a low-noise amplifier in the journal Electron Device Letters. The amplifier exhibited a minimum noise figure of 0.018dB across a bandwidth of 4-8GHz (A typical noise figure for low-noise amplifiers in mobile communication systems is tenths of a decibel). However, scaling up to larger quantities turned out to be very difficult.
Now, Chalmers, in collaboration with a company called Low-Noise Factory, has published an article describing a novel indium phosphide-based process for high electron mobility transistors (HEMT).
The transistors and other semiconductor components are fabricated on a an indium phosphide wafer. All parts of the design, such as semiconductor layers, components, process and circuit design, have been optimised for the lowest noise performance.
As a result, the team demonstrated an integrated 2.0 x 0.75mm amplifier with an ultra-low-noise figure of 0.045 dB, a bandwidth of 0.5-13GHz and a high gain exceeding 38dB across the frequency band. However, in order to achieve this performance, the amplifier was cooled to minus 260 degrees of Celsius.
“The combination of high gain, large bandwidth and ultra-low-noise figure makes this circuit very attractive for large multipixel arrays containing thousands of antennas,” says Jan Grahn, research group leader at Chalmers.
“The integrated ultra-low-noise process enables the fabrication of thousands of amplifiers with identical performance. One potential future application is in the world’s largest radio telescope SKA (Square Kilometer Array). In huge applications such as the SKA, even a small noise-figure reduction in the first low-noise amplifier in the receiver chain may potentially bring about major savings in the final system design.”