New-Tech Europe Magazine | August 2017

RF transceivers provide breakthrough SWaP solutions for defense and aerospace applications

DAVID BROWN, WYATT TAYLOR ANALOG DEVICES, INC.

Integrating more software control and cognitive abilities to military radios demands a more frequency- and bandwidth- flexible radio frequency (RF) design. To achieve this goal, static filters need to be removed and replaced with tunable filters. Similarly, the concept of a common platform would allow for shorter development times, reduced manufacturing costs, and provide greater interoperability between systems. The common platform demands that the RF system be capable of providing full performance for applications that traditionally have had very different architectures. Future radio platforms are pushing size and power demands to a new extreme. Since its inception, the super-heterodyne architecture has been the backbone of radio design for defense and aerospace systems. Whether it is a handheld soldier radio, unmanned aerial vehicle (UAV) data link, or a signal intelligence (SIGINT) receiver, the single- or two-mixing-stage super-heterodyne architecture is the common choice. The benefits of this design are clear: proper frequency planning can enable very low spurious emissions, channel bandwidth and selectivity is set by the intermediate frequency (IF) filters, and the gain distribution across the stages allows for a tradeoff between optimizing noise figure and linearity. (Figure 1.) During more than nearly one hundred years of use, the super-het architecture

has seen significant gains in performance across the entire signal chain. Microwave and RF devices have improved their performance while decreasing power consumption. Analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) have increased sample rate, linearity, and effective number of bits (ENoB). More performance gains: Processing capability in field- programmable gate arrays (FPGAs) and digital signal processors(DSPs) has followed Moore’s Law and increased with time, allowing for more efficient algorithms, digital correction, and further integration. Additionally, strides made in packaging technology have shrunk device pin density while simultaneously improving thermal device-specific improvements are beginning to reach handling. However, these

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