Low noise amplifiers in BAE Systems' Gallium Nitride MMIC technology

Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT) technology has received a large amount of attention in recent years for use in solid state power amplifiers (PAs). Although the initial focus of GaN MMIC development focused on high power transmit applications, the benefits of GaN in receiver applications have spurred interest in low noise amplifier (LNA) development. This thesis explores the use of BAE Systems' GaN MMIC technology, still in the development and optimization phase, in low noise applications. Two MMIC LNAs were designed, fabricated, and tested. The first MMIC fabricated was a common source LNA utilizing a single 0.35microm gate, 2x150microm finger dual field-plated device biased at 100mA/mm and 30V. This LNA had a noise figure less than 3dB, gain of 10 to 11dB, and an output third order intercept point (O1P3) of greater than 25dBm across the targeted frequency band. The second MMIC fabricated was a distributed LNA utilizing four 0.20microm gate 2x100microm dual field-plated devices biased at 100mA/mm and 15V. This LNA had a noise figure of from 3.1 to 6.7dB, nominal gain of 9dB, 2dB bandwidth from 1.7 to 19.5 GHz, and OIP3 above 25dBm across the targeted frequency band. The performance of these circuits was measured under a variety of bias conditions to better understand the performance and DC power consumption tradeoffs. The MMICs were compared to several other published GaN LNAs.