CORDIC-based window implementation to minimise area and pipeline depth

Abstract

Filtering is one of the most important modules in signal processing paradigm. This study presents a field-programmable gate array implementation of various window functions using coordinate rotation digital computer (CORDIC) algorithm to minimise area-delay product. First, the authors modify the Taylor series approximation order used in the scaling-free CORDIC, to completely eliminate the scale-factor and, yet, preserve the range of convergence spanning across the entire coordinate space. Secondly, the authors propose a new generalised technique for micro-rotation sequence identification to reduce the number of iterations required by the pipelined CORDIC processor. Then, this circular CORDIC processor is used to realise window functions. The existing window architecture uses a linear CORDIC processor in series with circular CORDIC processor, resulting in long pipeline. The authors replace the linear CORDIC with multiple optimised shift-add networks to reduce area and pipeline depth. As a result, the proposed window architecture, on an average requires approximately 64.34% less pipeline stages and saves up to 48% area. The authors have designed the processor to implement Hanning, Hamming and Blackman window families. The implementation of the proposed architecture is detailed in this study.