Professor of Electrical and Computer Engineering, University of California – Santa Barbara

Abstract: 5G offers the next step towards communication services that trade-off data rate, latency, coverage, and power consumption. However, an outstanding challenge not addressed with 5G is realizing a wireless technology that can transmit and receive in any RF channel under any interference environment. Considerable possibilities exist to investigate new wireless circuits and systems below 6 GHz. An example is full-duplex communication, which could theoretically improve the spectral efficiency or channel estimation. However, full duplex places significant dynamic range requirements on the receiver to tolerate the strong transmitter interference. I will present a code-domain multiple access technique that can realize more than 120 dB of self-interference rejection in the receiver while tolerating 30 dBm of transmit power. A key feature is code-domain filtering to relax the potential distortion generated in the receiver and realize a full-duplex link without significant power penalties at RF bands. Additionally, I will describe a complementary approach to digital modulation that mitigates out-of-band emissions due to switching. Code-domain transmitters and receivers have been realized in 45-nm SOI CMOS and will be presented for model/hardware correlation. I will also present research efforts that re-evaluate RF silicon photonic receivers to support RF and millimeter-wave MIMO. Silicon photonic devices offer a low-cost platform that might potentially support co integration of electronic and photonic circuitry. To overcome the spur-free dynamic range issues confronting RF electro-optic conversion, we will briefly review approaches to improve the linearity of silicon photonic modulators.

Bio: James F. Buckwalter is currently a Professor of Electrical and Computer Engineering with UCSB and was the recipient of a 2004 IBM Ph.D. Fellowship, 2007 Defense Advanced Research Projects Agency (DARPA) Young Faculty Award, 2011 NSF CAREER Award, and 2015 IEEE MTT-S Young Engineer Award. He is a senior member of the IEEE and has published more than 170 conference and journal papers on research related to RF, millimeter-wave, and high-speed optoelectronic circuits and systems.