AbstractsComputer Science

A low-noise microwave amplifier for spacecraft communication

by Ezra M. Long




Institution: California State University – Northridge
Department: Department of Elec & Comp Engr
Degree: MS
Year: 2015
Keywords: Deep Space Network; Dissertations, Academic  – CSUN  – Engineering  – Electrical and Computer Engineering.
Record ID: 2058097
Full text PDF: http://hdl.handle.net/10211.3/132981


Abstract

A microwave Low-Noise Amplifier (LNA), utilizing a Gallium-Arsenide (GaAs) pseudomorphic High-Electron-Mobility Transistor (pHEMT), has been developed. The LNA approached the limits of what is currently feasible in terms of noise performance. The theory necessary for designing low-noise microwave amplifiers is discussed. The concept of inductive negative source feedback is examined and utilized in the design. This feedback allows for the simultaneous optimization of the amplifier???s input return-loss and noise figure, while also enhancing its stability. A prototype LNA was constructed and measured in detail; the results track the three-stage amplifier analytical model well. The amplifier noise figure measured better than 1.0 dB across an 8???9 GHz frequency band. The gain of the LNA is greater than 20 dB while the input and output return losses are better than 20 dB. The LNA is unconditionally stable across all frequencies in which it has gain. Refinements were made to the analytical model to provide better agreement with the measured results. The amplifier can be used in a receiver for spacecraft communications where low-noise operation is vital to amplify the weak received signals. Various approaches to further improve the performance of future versions of this amplifier are suggested.