Low-Power mm-wave Circuits for Efficient Mobile Systems Beyond 5G
Emerging applications in mobile devices such as augmented/virtual reality (AR/VR), battery- powered wireless high-definition video systems, and lightweight drones all require increasingly high throughput communications. For this reason, mm-wave communication systems are an attractive option. However, such applications also require lightweight, low-power designs in order to maximize battery life. Unfortunately, most mm-wave transceivers designed for mobile 5G applications do not place power consumption at the top of the list in terms of optimization priority. Placing power consumption at the top of the list, with performance a close second, presents an opportunity to research and develop new radio architectures and circuit techniques to enable new classes of wireless applications beyond current 5G specifications.
In this work, we specifically aim to design mm-wave communication systems that improve energy efficiency and reduce power consumption over conventional approaches by at least an order of magnitude, all towards enabling next-generation applications beyond the capabilities of 5G systems envisioned in the immediate future. We aim to achieve this by exploiting the main resource offered at mm-wave frequencies: bandwidth. Rather than building complex OFDM waveforms with x-QAM symbols that require extremely linear front-ends, precision frequency references, and sophisticated basebands, it makes sense for these types of battery-powered applications to exploit lower-index modulation schemes that enable lower-complexity and therefore lower power implementations as a trade-off with spectral efficiency. Since bandwidth can be wide, energy efficiency can be obtained along with low-power operation by in- creasing modulation frequencies without a commensurate increase in linearity or phase noise require- ments. Further exploiting bandwidth towards extremely SNR-friendly schemes such as 16-FSK can help to improve link budgets while still supporting extremely high throughput. We plan to design radio front- ends along these lines, while also exploring several circuit-level innovations, including low-power integer-N frequency synthesis based on temperature-compensated FBAR resonators, and low-noise high-gain front-end structures based on regenerative amplifier concepts.