A look-up table VLSI design methodology for RNS structures used in DSP applications

In current high-speed digital signal-processing (DSP) architectures, the Residue Number System (RNS) has an important role to play. RNS implementations have a highly modular structure, and are not dependent upon large binary arithmetic elements. RNS implementations become more attractive when combined with the advantages offered by VLSI fabrication technology. In this paper, a novel design methodology has been developed for RNS structures, based on using look-up tables, which takes into consideration the unique features and requirements of RNS. The paper discusses the following three phases: 1) developing a look-up table layout model, which is used to derive relationships between the size of each modulus and both chip area and time; this model supports all types of moduli; 2) selecting the most efficient layout according to the design requirements; the procedure allows the designer to control the area, time, or the configuration of the memory module required for implementing a modulo look-up table; 3) proposing a set of multi-look-up table modules, to be used as building block units for implementing digital signal-processing architectures. The paper uses two examples to -illustrate the use of the modules in phase 3).