MULTISTAGE DECIMATION FILTER

This paper presents one method for a multiplierless FIR (finite impulse response) decimation filter design. The method is based on the IFIR (interpolated finite impulse response) structure and the sharpening techniques. It is supposed that the decimation factor can be presented as the product of two factors. In that way the expanded model filter can be moved to the lower rate. The coefficients of the model filter are rounded to the nearest integers and the sharpening technique is applied to the model filter in order to improve the magnitude characteristics of the overall filter. The interpolator is the cascaded RRS (recursive running sum) filter and the simple compensator. As result the overall structure is multiplierless and exhibits a high attenuation in the stopband and a low passband droop.