In oversampled Sigma Delta Analog Digital converters the signal is sampled by a rate which is much higher than Nyquist rate. However, at the output of the modulator, this rate should be decreased to a Nyquist rate. This process is called decimation. The process of decimation introduces aliasing which must be eliminated by a filter called antialiasing filter. The most simple antialiasing filter is comb filter which has all coefficients equal unity and consequently does not need multipliers for its implementation. There are two principal comb structures: recursive and no recursive. The recursive structure is an area efficient structure, while the no recursive structure is a power efficient structure. However, the magnitude characteristic of comb filter does not provide enough alias attenuations and additionally it has a droop in the passband which may deteriorate the decimated signal. Different methods have been proposed to improve comb aliasing rejection and decrease passband droop. We will present some the most popular methods to improve comb filter magnitude characteristic.

Gordana Jovanovic Dolecek received Bsc and PhD degree from the Faculty of Electrical Engineering, University of Sarajevo, Bosnia and Herzegovina, and Msc degree from University of Beograd, Serbia. In 1995 she joined Institute INAOE, Department for Electronics, Puebla, Mexico, where she works as a full professor. She was a visiting researcher with UCSB, Santa Barbara, USA in 2001-2002, and 2006, with SDSU San Diego, USA in 2008-2009, and with UCLA, Los Angeles, USA in 2015-2016.
She is author/coauthor of more than 70 journals and 400 conferences papers. She is author of the book: “Random Signals and Processes Primer with MATLAB,” Springer NY: 2013 and editor of books:”Advances in Multirate Systems”, Springer, NY, 2017, and “Multirate Systems: Design and Applications,” IGP, Hershey, USA, 2001.
In 2012 she received Science and Technology Puebla State award for her research work in electronics. 
Actually she is member of IEEE CAS DSP committee and RCM of IEEE ISCAS conference. She is a member of Mexican Academy of Sciences and SNI of Mexico.
She is the Associate Editor for IEEE Transactions on Circuits and Systems-I: Regular Papers, IEEE Transactions on Circuits and Systems-II: Express Brief, IEEE Circuits and Systems Magazine and IET Signal Processing. Her research interest includes digital signal processing, digital communications, and ML and applied mathematics in digital signal processing and digital communications.