Addressing Spectrum Congestion in 4G LTE and 5G Using Magnetostatic Wave Devices
The increasing density of the electromagnetic spectrum is driving carrier aggregation and dynamic spectrum reuse initiatives to help make the most out of this limited and valuable resource. With the number of wireless devices and data rates all projected to continue their meteoric rise these challenges will only become more exacerbated in the coming years. Research and development efforts funded by government agencies and major corporations around the world are pursuing a layered approach to mutual RF interference mitigation and spectrum use optimization. Magnetic devices present a unique set of capabilities to deal with RF interference problems. Epitaxial magnetic films sustain and propagate MagnetoStatic Waves (MSW), which are purely magnetic excitations that propagate up to 1000 times slower than the speed of light. This is very useful for 2 reasons: (i) filter structures with high Q-factor can be implemented in a compact form factor and (ii) delay lines with propagation delay of tens to hundreds of nanoseconds can be realized with relatively low insertion loss. As the frequencies and bandwidths of communications systems increase, it has become increasingly difficult for acoustic filter technology to accommodate those new requirements. For example, NR frequency bands n77, 78, and 79 are 900, 500, and 600MHz, respectively, a challenging fractional bandwidth requirement for acoustic filters given the 3750, 3550, and 4700MHz center frequencies. MSW devices offer new possibilities in the design of those filters because of less complex transducer and resonator geometries, lower propagation loss >1000MHz, and higher coupling coefficients. In addition to frequency filtering, delay lines based on MSW phenomena enable compact and high performance delay lines that are useful in active cancellation and beam steering techniques, given the relatively broad bandwidth and low loss. Lastly, in the nonlinear regime, MSW devices offer frequency selective power limiting that effectively extends the dynamic range of receivers. These and other applications of MSW technology, as well as the fundamentals of theory, design, simulation, and fabrication of devices using MSW phenomena will be discussed in this presentation.