基于改进CORDIC算法的快速幅频可调DDS技术

A high speed amplitude and frequency adjustable DDS technology based on improved CORDIC algorithm

针对传统直接数字频率合成器技术占用ROM资源较多以及传统CORDIC算法占用逻辑资源较多且不易进行快速幅值调整的不足,提出了一种改进的CORDIC算法,该算法可以快速调节DDS的幅值与频率。将CORDIC模块替换传统DDS中基于ROM查找表的相幅转换模块,从而节约ROM资源占用;通过免缩放因子技术来改进CORDIC算法,从而可以实现幅值的快速调整;结合迭代合并技术,提出了一种基于改进CORDIC算法的相幅转换模块,该模块免除了传统CORDIC算法中的旋转方向判断与循环迭代,从而大大降低了电路的逻辑资源占用。在FPGA平台上实现了该算法,并通过DAC模块输出模拟信号进行测量,实验结果表明该算法输出的正弦波幅值和频率具有较高的精度,调幅效果良好,适合于各种信号处理应用场合。

Aiming at the shortcomings that direct digital synthesizer circuit occupies more ROM resources and CORDIC algorithm occupies more logic resources and is hard to adjust the amplitude quickly,an improved CORDIC algorithm is proposed,which can quickly adjust the amplitude and frequency of DDS.The CORDIC module replaces the phase amplitude conversion module based on ROM look-up table in DDS,so as to greatly save the occupation of ROM resources.The CORDIC algorithm is improved by scaling-free technology,so that the amplitude can be adjusted quickly.Combined with iteration-merging technology,a phase amplitude conversion module based on improved CORDIC algorithm is proposed.The module eliminates the rotation direction judgment unit and cyclic iteration in the CORDIC algorithm,which greatly reduces the occupation of logic resources in circuit.The algorithm is implemented on FPGA platform,and the analog signal is output by DAC module for measurement.The experimental results show that the sinusoidal amplitude and frequency output by the algorithm have high accuracy and good amplitude modulation ability.It is suitable for various signal processing applications.