New realization and implementation of fixed-point IIR digital filters

A new low-roundoff noise realization for narrow-band IIR digital filters with residue feedback and a block triangular system matrix is presented. The block triangular form of the system matrix allows a reduction in the number of arithmetic operations required for the implementation and leads also to a realization which is suitable for high speed implementation. Numerical comparison between the proposed structure and three other low-noise structures shows that the proposed structure provides excellent performance in terms of output roundoff noise and coefficient sensitivity. The output roundoff noise is slightly higher than that of the optimal residue feedback realization proposed by Williamson⁹ but lower than the optimal realization without residue feedback proposed by Mullis, Roberts and Hwang.^6,7 Further, an efficient (in terms of speed) VLSI processor array implementation of the proposed HR structure is also presented. The proposed implementation has been obtained by taking advantage of both the parallel feature of the residue feedback and the block triangular structure of the system matrix of the proposed realization. A hardware comparison between the proposed implementation and another implementation which is based on direct form shows that the proposed implementation provides a higher sampling rate for any narrow-band filter.