J. O. Coleman


TITLE:
Express Coefficients in 13-ary, Radix-4 CSD to Create Computationally Efficient Multiplierless FIR Filters
AUTHORS:
J. O. Coleman
ABSTRACT:
A two's complement DSP signal can be multiplied by a fixed coefficient using an adder tree operating on input shifts corresponding to nonzero coefficient bits. Alternatively, the signed bits of a canonical signed-digit (CSD) coefficient representation specify an add/subtract network, with one third fewer terms required on average. That well-known approach is generalized here to a radix-4 CSD system that turns out to save 36% relative to conventional CSD in the FIR-filter application but at a per-filter overhead cost of six small-integer scaling operations that represent common subexpressions implicitly factored from the add/subtract network. The approach works for both direct-form and transposed-form filters and generalizes easily to other number systems.
DOWNLOADABLE PREPRINT:
PDF (185K),
STATUS:
Presented at the The 15th European Conf. on Circuit Theory and Design (ECCTD '01), Espoo, Finland, August 2001.
DATE OF ENTRY:
August 2001.