基于DSP Builder的双曲正切函数的FPGA实现

The FPGA Implementation of Hyperbolic Tangent Function Based on DSP Builder

为了保证双曲正切函数在FPGA上实现时能够获得较高的精度和较快的速度,并且消耗较少的资源,在分析现有实现方法优缺点的基础上,提出了分段逼近线性近似法。首先,在理论上,分析了该方法所能达到的精度,给出了数据的定点表示方法。然后,通过Altera公司的系统级数字信号处理,开发工具DSP Builder搭建系统模型并转换得到相应的VHDL代码。最后,通过Modelsim进行时序仿真,验证了该方法的正确性和可行性。结果表明,该方法仅占用芯片EP4CE10F17C8L约1%的逻辑资源,完成一次运算仅需9.88ns,近似计算的最大绝对误差为4e-6。

In order to ensure the higher precision and faster speed of the hyperbolic tangent function implemented on FPGA,a piece wise line arapproximation approach method with fewer consumer of resources is proposed based on the analysis of the advantages and disadvantages of existing implementations.Firstly,the method isanalyzed the oretically for achievableaccuracy infixed pointdata,then a systemmodel is builtthrough the system-level digital signal processing developmenttool named DSP Builder from Altera.The model can be convert into VHDL code by DSP Builder.Finally the timing simulation through Modelsim shows the correctness and feasibility of the method.This method is only to consume about 1% chiplogic resources of EP4CE10F17C8 L,to completea computation for 9.88 ns,and them axabsoluteerroris 4e-6.