The single most important function in electronics is amplification. This is fundamentally limited by noise in the electrical signal. In applications such as quantum information systems, deep-space communication and radio telescope arrays, the noise in the incoming signal may limit the whole system performance. Minimizing the noise level in the amplifier is therefore of interest not only for increased sensitivity in detection of weak signals but also for exploring the fundamental limits in electronic amplification ultimately determined by quantum physics.
Our quest is the search for the lowest noise amplifier at frequencies from 1 GHz to several hundreds of GHz. The heart of the semiconducting amplifier is the transistor. We study the physics and technology of the high-electron mobility transistor uniquely engineered to amplify with lowest noise. The key material of the transistor is a semiconductor heterojunction of InGaAs-InAlAs. Our research therefore spans from understanding compound semiconductor materials to the full amplifier design optimized for lowest noise. These includes device physics, nanofabrication of transistors in the cleanroom, microwave circuit design and delicate noise measurements. Our research has helped to advance several state of the art results for lowest noise and dc power in microwave amplification. From our group, the company Low Noise Factory AB was spun off which is now one of Sweden’s largest microwave companies.
