CIC-BASED DECIMATORS

Guest Speaker: Gordana Jovanovic Dolecek,
Department of Electronics
Institute INAOE, Puebla, MexicoABSTRACT: Sampling rate conversion (SRC) is one of the most frequent and useful tasks in the field of communication. SRC involves resampling which itself causes aliasing and imaging. The elimination of the detrimental effects of these two fundamental characteristics of resampling requires filtering. Thus the design of a SRC system is basically a filter design problem. Whenever the sampling rate exceeds the minimum requirement posed by the Nyquist criterion, it is reasonable to try to reduce it. This means that we can eliminate some of samples, and still have a good representation of the signal. The reduction of a sampling rate is called decimation, because the original sample set is reduced (decimated). Decimation consists of two stages: filtering and downsampling A commonly used decimation filter is the cascaded-integrator-comb (CIC) filter, which consists of two main sections: an integrator and a comb, separated by a down-sampler. This filter has many desirable characteristics making it very attractive for different applications. However, the frequency response of the CIC filter does not satisfy the desired specifications, i.e., the CIC filter has a high passband droop and a low stopband attenuation. The latter can be improved by increasing the number of the cascaded CIC filters resulting in a higher passband droop. Additionally the integrator section works at the higher input data rate resulting in a larger chip area and higher power consumption especially when the decimation factor and the filter order are high. Different methods have been proposed to improve the characteristics of CIC decimator while keeping its simplicity. The methods either improve the passband or stopband of the CIC filter. There exist also methods to improve both, stopband and the passband. We will present CIC filters, and the state of the art in the designing of CIC-based decimators.BIOGRAPHY: Gordana Jovanovic Dolecek received a B.S. degree from the Department of Electrical Engineering, University of Sarajevo, an M.Sc. degree from University of Belgrade, and a Ph.D. degree from the University of Sarajevo in Bosnia. She was a Professor of Electrical Engineering, University of Sarajevo until 1993, and from 1993 to 1995 she was with the Institute Mihailo Pupin, Belgrade. In 1995 she joined the Department for Electronics at the Institute INAOE, Puebla, Mexico, where she is presently a professor. During 2001-2002 and also during 2006, she was a visiting scholar at the Department of Electrical & Computer Engineering, University of California, Santa Barbara. She is presently at the San Diego State University on a sabbatical leave. She is the author of three books, editor of one book, and author of more than 200 papers. Her research interests include digital signal processing and digital communications. She is a Senior Member of IEEE, a member of Mexican Academy of Sciences, and a member of National Researcher System (SNI), Mexico.Host: Professor Sanjit K. Mitra

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Talyia Veal