This paper presents an improved VLSI (Very Large Scale of Integration) architecture for\nreal-time and high-accuracy computation of trigonometric functions with fixed-point arithmetic,\nparticularly arctangent using CORDIC (Coordinate Rotation Digital Computer) and fast magnitude\nestimation. The standard CORDIC implementation suffers of a loss of accuracy when the magnitude\nof the input vector becomes small. Using a fast magnitude estimator before running the standard\nalgorithm, a pre-processing magnification is implemented, shifting the input coordinates by a proper\nfactor. The entire architecture does not use a multiplier, it uses only shift and add primitives\nas the original CORDIC, and it does not change the data path precision of the CORDIC core.\nA bit-true case study is presented showing a reduction of the maximum phase error from 414 LSB\n(angle error of 0.6355 rad) to 4 LSB (angle error of 0.0061 rad), with small overheads of complexity\nand speed. Implementation of the new architecture in 0.18 �¼m CMOS technology allows for\nreal-time and low-power processing of CORDIC and arctangent, which are key functions in many\nembedded DSP systems. The proposed macrocell has been verified by integration in a system-on-chip,\ncalled SENSASIP (Sensor Application Specific Instruction-set Processor), for position sensor signal\nprocessing in automotive measurement applications.
Loading....