A novel technique for the pre-computation of rotation bits for unidirectional CORDIC is developed in the VLSI Systems Laboratory. The unidirectional CORDIC algorithms differs from the conventional CORDIC in the degree of rotation. In the conventional algorithm, the rotation of the angle is in both clockwise and counterclockwise directions, but the rotation is only in counterclockwise direction in unidirectonal CORDIC algorithm. This leads to no rotation for few bits thereby reducing the number of rotations required to compute a value. Hence the unidirectional CORDIC approach has significant improvement in speed and power savings. A new technique is being developed to pre-compute the rotation bits from any given angle.

References

[1]    Jack E. Volder, “The CORDIC Trigonometric Computing Technique,” IEEE Trans. Electronic Computers, Sep.1959, pp.330-334.

[2]    J.S, Walther,  “A Unified Algorithm for Elementary Functions,”  Proc. Joint Computer Conf., 1971, pp 379-385.

[3]    Y.H. Hu, “CORDIC-Based VLSI Architecture for Digital Signal Processing,” IEEE Trans. Computers, Jan 1993, vol.42, no.1, pp.99-102.

[4]     H. Dawid and H.Meyr, “The Differential CORDIC Algorithm: Constant Scale Factor Redundant Implementation without Correcting Iterations,” IEEE Trans. Computers, Mar. 1996, vol.45, no.3, pp.307-318.

[5]      Elisardo Antelo, Julio Villalba, Javier D. Bruguera, and Emilio L. Zapata, “High Performance Rotation architectures Based on the Radix-4 CORDIC Algorithm,” IEEE Trans. Computers, Aug. 1997, vol.46, no.8, pp.855-870.

[6]      M. Kuhlmann and K. K. Parhi, “A High-Speed CORDIC Algorithm and Architecture for DSP applications,” IEEE Workshop on Signal Processing Systems (SiPS) Design and Implementation, Taipei, Taiwan, Oct 1999.

[7]     Yu Hen Hu and Homer H.M. Chern, “A Novel Implementation of CORDIC Algorithm Using Backward Angle Recording (BAR),” IEEE Trans. Computers, Dec. 1996, vol.45, no.12, pp.1370-1378.

[8]     Shaoyun Wang, Vincenzo Piluri and Earl E. Swartzlander, “Hybrid CORDIC Algorithms,” IEEE Trans. Computers, Nov. 1997, vol.46, no.11, pp.1202-1207.

[9]     Ray Andraka, “A survey of CORDIC algorithms for FPGAs,” FPGA '98, Proceedings of the 1998 ACM/SIGDA sixth international symposium on Field programmable gate arrays, Monterey, CA, Feb. 1998, pp191-200.

[10]      B. Gisuthan, T. Srikanthan and K. Vijayan Asari, "Design of an Efficient Digital Architecture for the Pre-Synthesis of Direction of Micro-Rotations in Flat-CORDIC," Proc. Second International Conference on Information, Communications & Signal Processing - ICICS'99, Singapore, Dec 1999, no. 2b2-1, no. 261, pp. 01-05.

[11]     T. Srikanthan, B. Gisuthan and K. V. Asari, "An Area-Time-Power Optimization for Radix-2 Redundant CORDIC Rotation Engines," Proc. SPIE International Symposium on Microelectronics and Micro Electro Mechanical Systems, Queensland, Australia, Oct 1999, vol. 3893, no. 47, pp. 421-432.

[12]  Satish Ravichandran and Vijayan K. Asari, "VLSI Architecture for Pre-computation of Rotation Bits in Unidirectional Flat-CORDIC," Proceedings of 10th NASA Symposium on VLSI Design, Albuquerque, New Mexico, USA, Mar 2002, pp. 3.2.1-3.2.6