Shared multiplication for constant and adaptive digital filters

Abstract

A machine or method used for reducing the implementation cost of digital filters that use multiplication operations. For each new input, a small look-up table of products is computed and stored. Weighting of the inputs when computing digital filter outputs can be accomplished using look-up table access, shifting, and addition. The invention can be used for constant filters or for adaptive filters. With constant filter coefficients, a small look-up table which exploits the properties of the various coefficient representations as a group is possible. With adaptive filters, a larger table may be needed, but can be used to reduce the multiplication cost of both filter output computation and filter adaptation. The invention is particularly useful in technologies where general multiplication is costly, such as field programmable gate arrays, application specific integrated circuits, and software running on general-purpose microprocessors. The invention can be used for high-precision computations without the need for large look-up tables. The invention can lead to digital filter implementation with reduced chip space, computation time, and power consumptions relative to implementations that do not share processing among multipliers.

Drawings

Dependencies are inferred from the claim text.