A class of high-precision multiplier-free FIR filter realizations with periodically time-varying coefficients

Proposes a class of high-precision, multiplier-free realizations for FIR filters. These realizations use upsampling and downsampling in conjunction with a periodically time-varying system to achieve time-invariant, multiplier-free FIR filter operation. Nonbinary encoding schemes are used for obtaining the filter coefficients, which are periodically time-varying (PTV), i.e., they vary in a periodic fashion. Each target filter coefficient is directly mapped into a set of PTV coefficients so that the realizations are easy to obtain. The values of the PTV coefficients are restricted to either the ternary set {±1, 0} or the quinary set {±2, ±1, 0} so that the realizations can be implemented with only add/subtract and one-bit shift (for the quinary case) operations. A few shift-and-add operations are also needed at the beginning and the end of the structure. Coefficient precisions (in bits) of these realizations are given and they are sufficiently high for most applications. Advantages of the proposed realizations accrue at the expense of a higher clock rate