Titre: Spread Spectrum Clock Generator Circuit Design for EMI Reduction
Conférencier: Tian Xia , Université du Vermont, É.-U.
Lieu: UQAM, Pavillon Président Kennedy, PK-4610 ,
Date et heure: vendredi le 05 juin 2009 de 10:00 à 12:00

Résumé: Today most digital systems are synchronous designs triggered by a synchronous clock. Due to its periodic feature, the digital system has the highest spectral density at the clock frequency and its harmonics, which results in the highest electromagnetic radiations at these frequencies. Such radiations may violate the regulatory limits for electromagnetic interference (EMI). To alleviate this issue, a straightforward solution is metal shielding. However it will significantly increase the fabrication cost, and sometimes is not feasible, for instance in small size portable commercial electronics devices. Since EM radiation concentrates at certain frequencies, by spreading the clock energy over a large frequency band, the EM radiation strength can be brought down. Such method is simply and low cost. In this talk, I will first introduce a spread spectrum clock generator (SSCG) circuit design that adopts a standard integer-N phased locked loop (PLL) with dual-loop configuration and direct VCO modulation. A digital frequency limit detector and a simple integrator are implemented to direct the spectrum-spreading profile generation. Comparing with other designs in the recent literature, our method is simple and area efficient. The experimental results show that the proposed design can effectively produce 0.5% to 3% spectrum spread ratios and reduce clock signal peak power up to 12 dB. In addition, I will introduce some on-going projects in my Micro-Electronics System group at the University of Vermont.

Note biographique: Dr. Tian Xia received the B.E. degree in Electrical Engineering from the Huazhong University of Science and Technology, China, the M.S. degree from the Nanjing University of Posts and Telecommunications, China, and the Ph.D. degree in Electrical and Computer Engineering from the University of Rhode Island. He worked in IBM T.J. Watson Research Center in summers of 2002 and 2003 on SiGe circuit design and test. He joined the University of Vermont as an assistant professor in 2003. He is currently an associate professor with the School of Engineering. His research focuses on mixed signal VLSI circuit design and test.

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