Novel receivers target world’s largest radio telescope

A Canadian graduate student’s MSc project from nearly 20 years ago, and more recent projects, are contributing to one of the most fascinating new instruments in the history of astronomy: the Square Kilometer Array (SKA).

The largest radio telescope in the world, and 50 times more sensitive than existing radio telescopes, the SKA will link thousands of parabolic dishes situated in remote desert regions of Central Africa and Australia, providing a scanning area of one million square kilometres.

Astronomers say it will help them answer some of the biggest questions in their field. They plan to use it to study the evolution of the first stars and galaxies, to learn more about gravitational waves and cosmic magnetism, and to look for life elsewhere in the universe.

These investigations could greatly benefit from the ingenuity of Leonid Belostotski and his PhD supervisor at University of Calgary, Dr. James Haslett. Their pioneering research in the mid-2000s solved a practical problem with the SKA: how to capture specific deep space signals buried within a blizzard of atmospheric clutter, comprising unwanted signals and receivergenerated static without consuming many hundreds of kilowatts of power to cool and power receivers.

Now Canada Research Chair in High-Sensitivity Radiometers and Receivers, and Professor of Electrical and Computer Engineering at University of Calgary, Dr. Belostotski and his colleagues are working on low-noise focal plane arrays, a key piece of the project, and one of a number of “demonstrator” components that may ultimately become part of the constructed instrument. The arrays are composed of about 200 antennas and would be positioned at the focal plane of each of 10,000 telescope dishes.

A significant piece of this work is the development of ultra-low-noise CMOS receivers for use in the arrays. Normally, the receivers in radio telescopes are cooled cryogenically, to reduce signal noise. But the vast scale of the SKA would make that too expensive, so Belostotski, Dr. Haslett, and a team of graduate students in collaboration with researchers from the NRC Herzberg (Penticton), have developed a receiver that will work at room temperature.

“The idea was that we do not want cryogenic cooling because with 10,000 dishes we potentially need a million receivers and that’s too expensive. We needed a process that is amenable to mass production,” says Belostotski.

Radio signals are emitted by a large number of sources in the universe. Radio telescopes detect these weak signals, which are then processed and turned into images.

“The signals we receive are very faint, and we can’t afford to add any more noise to them,” Belostotski says. “The higher the receiver operating temperature, the more the noise. We figured out a way to design receivers that add very little noise to incoming signals, but without cryogenic cooling.”

CMC Microsystems played a major role in this work, providing CAD tools to help the team design the receivers, and access to foundry processes for fabrication, says Belostotski, with the receiver being successfully fabricated using a 65-nanometer CMOS process through TSMC. “The receivers are integrated circuits that were all fabricated with help from CMC,” he says. “We are very dependent on IC fabrication. Without these resources, our contribution to this international project would not be possible.”

There is also economic opportunity in this exciting science and engineering research, says Dan Gale, Vice-President and CTO of CMC. “Dr. Belostotski’s work creates technologies that can be used again and again. His very clever design and extraordinary measuring techniques and custom instrumentation offer benefits to industries looking to design low-noise circuits. This is a major communications accomplishment.”

Belostotski and his colleagues will know by the middle of next year if their low-noise focal plane array has been chosen to be part of the SKA project. Belostotski’s involvement began when he was a graduate student at University of Alberta in 1997, six years after the multinational project was born.

He is proud to have been part of the development on the SKA, and, following in the footsteps of his mentor, he, too, is helping to create a new generation of innovators: his work, enabled by CMC simulation tools, has led to a startup company he has launched with Michael Himmelfarb, one of his students. NoiseTech Microwaves is developing equipment that engineers or designers can use to quickly and reliably measure noise parameters when they are working on amplifiers in receivers.

July 2016

Printable version