Silicon amplifier for millimetric frequencies

New imaging and high-capacity wireless communications systems are one step closer to reality, thanks to a millimetre wave amplifier invented at the University of California.

The silicon-based device marks progress towards high-capacity wireless communications systems that will operate at millimetre wave frequencies (60–120 GHz) and could provide data transfer rates to 10 gigabits per second over a kilometre.

Towards this goal, the amplifier provides both high gain and high bandwidth. It has a direct transmission line path from the input to the output that carries the signal across the surface of a silicon chip.

Amplification 'stages' along this transmission line boost the signal power by monitoring the signal amplitude and generating feedback in just trillionths of a second, feedback that injects additional energy in phase to the signal.

The amplifier provides gain of 26–30 dB at 100 GHz and allows wave propagation along the chip surface.

James Buckwalter, an assistant professor in the Department of Electrical and Computer Engineering at UC's Jacobs School of Engineering, invented the amplifier and named it the cascaded constructive wave amplifier.

“Cascaded constructive wave amplification is a new circuit architecture that can push silicon into new operating regimes near the fundamental limits of Moore’s Law and allow the ultra high data rates that the millimetre wavelength range of the electromagnetic spectrum offers,” explained Buckwalter.

The millimetre wavelength range of the electromagnetic spectrum is relatively unexplored for commercial use, in part, because it has been difficult and expensive to build the necessary high-frequency amplifiers.

Many of today’s millimetre wave amplifiers, for example, require exotic and expensive semiconductor materials.

“We’re exploring how silicon can play a role at frequencies exceeding 100 GHz. Silicon has the advantage of allowing inexpensive integration of microwave and now perhaps millimetre wave components,” said Buckwalter.