Jeffrey S. Walling
Harry Lynde Bradley Department of Electrical and Computer Engineering
Seminar: Pathways to Direct-digital Beamforming Using the Switched-capacitor Power Amplifier, from RF to mmWave
Abstract: Mixed-mode transmitters have the ability to directly convert digital signals to modulated RF signals and have been demonstrated to be more linear, efficient and physically smaller than traditional analog transmitter chains. In the first part of this talk, I will introduce mixed-signal transmitters and highlight the switched-capacitor power amplifier. Because mixed-signal transmitters can be made to output any arbitrary amplitude and phase, they are ideal for usage in beamforming systems. Digital beamforming can enable increased throughput by allowing for multiple spatial streams, enabling multiple simultaneous wireless links from a single antenna aperture. Typically, one data converter is needed per stream, which requires significant power and hence fully digital beamforming has been reserved for highly specialized hardware. The switched-capacitor power amplifier can enable direct connection of the digital baseband to the antenna due to its direct digital-to-RF operation. I will highlight a path towards direct digital beamforming using a multiphase switched-capacitor power amplifier and highlight recent research that has enabled the amplifier to operate to near mmWave frequencies.
About the Speaker: Dr. Walling earned his Ph. D. degrees from the University of Washington, Seattle, in 2008. He has held various positions in industry and academia for more than 20 years with extensive focus on RF/analog/mixed-signal design for wireless transceivers. He is presently an associate professor in the Bradley Electrical and Computer Engineering Department at Virginia Tech. His research is focused on RF/Analog/Mixed signal circuits from RF to THz. He earned the Outstanding Teaching Award at the University of Utah in 2015 and the HKN Award for Excellence in Teaching in 2012.
Host: Members of the MTT student chapter advised by Steven M. Bowers, associate professor of electrical and computer engineering.