Ramesh Harjani University of Minnesota

CMOS Analog Circuits for Wireless Communications

The desire for wireless portable solutions requires extremely compact and low power circuit designs. In particular, RF CMOS designs are extremely attractive because it allows us to integrate powerful digital signal processing algorithms on the same substrate. In this talk we will be providing an overview of some of the wireless communications circuit designs currently underway at the University of Minnesota. Voltage controlled oscillators (VCOs) are critical components in communications devices and often set the performance of the overall system. Ring oscillator based VCOs are particularly attractive because they provide extremely wide tuning range, are compact and able to accommodate large process variations. However, they are normally considered to have extremely poor noise characteristics. We shall describe some of our recent developments in low phase noise VCO designs. We will provide both theoretical and measurement results to show that ring oscillator based VCOs can have extremely low phase noise, i.e., comparable to LC oscillators. We will also show that the performance is likely to improve with smaller feature sizes in newer generation processes.

Bio
Ramesh Harjani (S'87-M'89-SM'00) is an Assoc. Professor in the Electrical Engr. dept. and a graduate faculty member of the Biomedical Engr. dept. at the University of Minnesota. He received his Ph.D. in Electrical Engineering from CMU in 1989, his M.S. in Electrical Engineering from the Indian Institute of Technology, New Delhi in 1984 and his B.S. in Electrical Engineering from the Birla Institute of Science and Technology at Pilani in 1982. He was with Mentor Graphics Corporation from 1989 to 1990 and worked on CAD tools for analog synthesis and power electronics. He has also had a number of short stints as a member of the technical staff at Lucent Technologies and worked on data converters for DSL. His research interests include wireless communications circuits, low power analog design, sensor interface electronics and analog and mixed-signal circuit test. Dr. Harjani received the National Science Foundation Research Initiation Award in 1991. He received a Best Paper Award at the 1987 IEEE/ACM Design Automation Conference and an Outstanding paper award at the 1998 GOMAC. His research group was the winner of the SRC Copper Design Challenge "RF Front-End Design with Copper Passive Components".