Dual-Band and Broadband RF Power Amplifiers for Concurrent Signal Transmission

Broadband power amplifiers are becoming increasingly important for communications andradar phased array applications. Amplifying concurrent signals allows for increased data through- put with carrier aggregation and improved radar tracking performance, among other benefits. However, non-concurrent broadband amplifier design is limited in performance by fundamental matching limitations, and suffers further in the concurrent mode due to signal mixing. To reduce the cost of phased arrays, a low-cost GaN-on-Si technology is first investigated on which broadband power amplifiers are designed and fabricated. Various passive structures are simulated to validate process stack-up simplifications, along with the design and characterization of a narrowband proof-of-concept X-band power amplifier. Fundamental limitations are summarized and utilized to develop a design procedure for multi-stage power amplifiers with increased gain for phased array applications. This procedure is confirmed with a fabricated matching network. These results are then used in dual-band and broadband power amplifiers designs, which are fabricated with commercially available GaAs and GaN technologies. Hybrid and MMIC implementations in both cover 2-18 GHz in aggregate. The power amplifier characterization focuses on comparing each implementation in the non- concurrent and concurrent mode to understand the effect each power amplifier has on signal ampli- fication. A new broadband power amplifier architecture is developed to improve the performance of broadband power amplifier amplifying concurrent signals. Results indicate that a PA with this architecture can achieve similar power and efficiency as compared to a standard broadband PA, whereas linearity can be improved and/or simplified using this approach.</p