A compensated three-stages sharpened comb decimation filter
M.G.C. Jimenez G.J. Dolecek · 2015
The comb filter is popular due to its simplicity and is usually used in the first stage of a decimation process. The Cascaded-Integrator-Comb (CIC) structure, used for the efficient implementation of the comb filter, was proposed by Hogenauer (1981). The transfer function of K cascaded comb filters is where M is the decimation factor. Nevertheless, the comb filter has a high passband droop and poor attenuation in the folding bands (bands around the zeros of the comb filter). Thus, different methods have been proposed to solve these problems. Among them, for example the works of Kim et al. (2006), Molnar & Vucic (2006), Romero & Dolecek (2013) and Dolecek & Fernandez (2014) are devoted only to improving the magnitude characteristic in the passband region. Similarly, the methods of Presti (2000), Laddomada (2007) and Coleman (2012) improve the attenuation in the folding bands. Methods byKwentus et al. (1997), Fernandez&Dolecek (2009) and Zaimin et al. (2011) improve both, passband and stop-band characteristics. In the works of Dolecek & Mitra (2005), Dolecek & Salgado (2012), Jimenez & Dolecek (2013) and Jimenez et al. (2013), the improvement of the worst case magnitude characteristics of comb filters in the passband and the first folding band (the most critical bands) has been addressed.As a consequence, one can obtain less complex structure in comparison to cases where the passband and all the folding bands are improved.