Generalized Hyperbolic CORDIC and Its Logarithmic and Exponential Computation With Arbitrary Fixed Base
Yuanyong Luo, Yuxuan Wang, Yajun Ha, Zhongfeng Wang, Siyuan Chen, Hongbing Pan · IEEE Transactions on Very Large Scale Integration (VLSI) Systems · 2019
This paper proposes a generalized hyperbolic COordinate Rotation Digital Computer (GH CORDIC) to directly compute logarithms and exponentials with an arbitrary fixed base. In a hardware implementation, it is more efficient than the state of the art which requires both a hyperbolic CORDIC and a constant multiplier. More specifically, we develop the theory of GH CORDIC by adding a new parameter called base to the conventional hyperbolic CORDIC. This new parameter can be used to specify the base with respect to the computation of logarithms and exponentials. As a result, the constant multiplier is no longer needed to convert base e (Euler's number) to other values because the base of GH CORDIC is adjustable. The proposed methodology is first validated using MATLAB with extensive vector matching. Then, example circuits with 16-bit fixed-point data are implemented under the TSMC 40-nm CMOS technology. Hardware experiment shows that at the highest frequency of the state of the art, the proposed methodology saves 27.98% area, 50.69% power consumption, and 6.67% latency when calculating logarithms; it saves 13.09% area, 40.05% power consumption, and 6.67% latency when computing exponentials. Both calculations do not compromise accuracy. Moreover, it can increase 13% maximum frequency and reduce up to 17.65% latency accordingly compared to the state of the art.