Multiplierless implementation of bandpass and bandstop IIR digital filters

Some low-sensitivity transformations are investigated, wherein a prototype lowpass filter is transformed into a bandpass (bandstop) filter with low-sensitivity using such transformation. The modified coefficients being quite small, they require few shifts and adds and/or subtracts for implementation when these are expressed in minimum signed powers of two (MNSPT) forms or canonic signed digit (CSD) forms, and we obtain a multiplierless realization. Allowing some marginally insignificant deviation in the specification including the tolerances and the bandedges, the number of shifts and adds and/or subtracts per multiplier becomes quite small to make this approach quite attractive. Alternatively, we can design the prototype lowpass filter with marginally stricter tolerances than the desired specifications. Our analysis confirms this approach to be a viable one for multiplierless realization of bandpass and bandstop filters.