March 17, 2008
EE Conference Room 1312 S.W. Mudd
Hosted by: Prof. Peter Kinget
Speaker: Prof. Ranjit Gharpurey, University of Texas at Austin
The problem of interference continues to become progressively severe in modern wireless systems, owing to greater utilization of spectrum. Simultaneously, the data rate in many systems continue to increase. Radio front-ends for such systems thus have to satisfy ever more stringent dynamic range requirements. This can pose an especially severe challenge in short-channel CMOS implementations, due to the relatively low supply voltages of these technologies.
Radio front-end architectures that can alleviate the above dynamic range challenge are presented in this talk. We begin by examining a low-power recursive radio front-end topology, that utilizes transconductance at multiple frequencies. The next part of the talk addresses our recent work in the area of radio front-ends that utilize feedforward auxiliary paths to cancel interferers at critical points with the receiver chain. The technique can be used for canceling multiple narrowband interferers as well as for achieving broadband attenuation, without the use of external passive SAW or ceramic filters and with minimal impact on in-band sensitivity. Recent work on combining active cancellation with interference detection is presented. An architecture for broadband interference sensing, that utilizes a cascade of image reject stages is also discussed.
It is expected that many of these approaches will be useful in emerging broadband wireless systems as well as Cognitive Radio and Software Defined Radio systems.
Dr. Ranjit Gharpurey is with the Dept of Electrical and Computer Engineering at the University of Texas at Austin. He received his PhD from the University of California at Berkeley in 1995 and his B. Tech from the Indian Institute of Technology, Kharagpur in 1990. His areas of research interest include RF and high-frequency analog IC design.
Dr. Gharpurey is currently serving on the technical program committees of CICC, ISSCC and RFIC conferences, and is an associate editor of the IEEE Journal of Solid State Circuits.