Gray Encoded Arithmetic Operators Applied to FFT and FIR Dedicated Datapaths

  • Eduardo A. C. da Costa
  • Jose C. Monteiro
  • Sergio Bampi
Part of the IFIP International Federation for Information Processing book series (IFIPAICT, volume 200)


This paper addresses the use of low power techniques applied to FIR filter and FFT dedicated datapath architectures. New low power arithmetic operators are used as basic modules. In FIR filter and FFT algorithms, 2’s complement is the most common encoding for signed operands. We use a new architecture for signed multiplication, which maintains the pure form of an array multiplier. This architecture uses radix-2m encoding, which leads to a reduction of the number of partial lines. Each group of m bits uses the Gray code, thus potentially further reducing the switching activity both internally and at the inputs. The multiplier architecture is applied to the DSP architectures and compared with the state of the art. Due to the characteristics of the FIR filter and FFT algorithms, which involve multiplications of input data with appropriate coefficients, the best ordering of these operations in order to minimize the power consumption in the implemented architectures is also investigated. As will be shown, the use of the low power operators with an appropriate choice of coefficients can contribute for the reduction of power consumption of the FIR and FFT architectures. Additionally, a new algorithm for the partitioning and ordering of the coefficients is presented. This technique is experimented in a Semi-Parallel architecture which enables speedup transformation techniques.

Key words

Hybrid encoding DSP architectures power consumption 

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Copyright information

© International Federation for Information Processing 2006

Authors and Affiliations

  • Eduardo A. C. da Costa
    • 1
  • Jose C. Monteiro
    • 2
  • Sergio Bampi
    • 3
  1. 1.Universidade Católica dePelotas (UCPel)PelotasRS-Brazil
  2. 2.Instituto de Engenharia e Sistemas de Computadores (INESC-ID)LisboaPortugal
  3. 3.Universidade Federal do Rio Grande do Sul (UFRGS)Porto AlegreRS-Brazil

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