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262                                                Chapter 6 DSP Algorithms

        and by iterating L steps ahead we get






        where





















        and



            We assume that these matrices can be precomputed and neglect the fact that
        the word length of the matrix coefficients increases. Hence, Equation (6.3) can be
        iterated with an iteration period that is the same as the original set of state-space
        equations, but L output values are computed at each iteration. The effective iteration
        bound has therefore been decreased. We define a high-speed digital filter structure
        as a structure whose throughput is not bounded by the multiplication cycle time.

            Theorem 6.5
            The minimum sample period for block processing of an TVth-order state-
            space algorithm is




            where T mui t + Flog2(-/V+l)l T a(j^ is the total delay (latency) due to the arith-
            metic operations and L is the block size.

        The number of operations per sample is






        where the first term is the number multiplications, the second term is the number
        of additions, and N is the filter order.
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