Ultra-Low Noise Amplifier for Enhanced Signal Intelligence (SIGINT) Detection

The goal of this proposed project is to design, fabricate and characterize ultra-low-noise amplifiers for radar and signal intelligence applications. High frequency, wide bandwidth signals have several advantages in applications ranging from high data rate communications to high resolution radar. However, the biggest challenge to realizing these systems is limitations to the amplifier noise performance. Advanced transistor technologies based on compound semiconductor transistors (such as pHEMTs and mHEMTs) have been reported to possess lower noise figures and higher frequencies of operation than conventional silicon-based transistors, principally due to their higher electron mobilities. In Phase I, preliminary designs of low-noise, ultra wideband amplifiers employing mHEMTs as the active devices and feed-forward noise cancellation circuits were created. Simulations show that noise cancellation circuits decrease thermal noise and increase gain. The principal result is a reduction in the noise figure. We propose a Phase II program that will build on the Phase I foundation by undertaking simulations with more realistic components and perform further optimizations. Additional work will be undertaken to extend the mHEMT model to cryogenic temperatures. We will first implement the amplifier as a hybrid circuit and test it. This will be followed by a monolithic implementation. BENEFIT: The proposed design efforts have numerous direct applications ranging from wireless communication, optical free space communication, commercial radar, high quality wireless video communications, next-generation cell phones and GPS receivers. While compound semiconductor-based devices are commonly used in military systems, their cost and level of maturity still limit their commercial applications. However the volume production of lower cost high-frequency and low-noise amplifiers becomes realistic as the demand for wide-bandwidth and high-performance amplifiers increases. It is anticipated that the commercial market will rapidly overtake the military one as the level of product maturity increases.