对传统DDS技术的频率分辨率、相位分辨率进行了分析，并对其结构进行了优化，使得频率分辨率、相位分辨率是10的负整数幂，不存在尾数，提高了DDS输出频率及相位的精度。通过合理选择采样点数、正弦值二进制位数，有效减小了由相位截断误差引起的运算杂散，提高了信噪比。在优化DDS基础上设计了三相精密程控标准源，能够叠加2~31次谐波，输出波形过渡平稳，无振荡及尖峰毛刺。输出基波电压以及电流误差小于0.05%，频率分辨率高。%This paper optimizes the traditional DDS structure based on the analysis of frequency resolution and phase resolution of traditional DDS technology, which are negative power of 10 without mantissa. So the accuracy of frequency and phase is improved. Through the reasonable selection of sampling points number and sine value bits number, the spurs caused by phase truncation is effectively reduced and the SNR is raised. The paper designs the three-phase precise programmable standard source on the basis of optimized DDS, which can overlape 2~31 harmonic. The output wave transition is smooth without oscillation and peak burr. The error of output fundamental voltage and current is less than 0.05%and the frequency resolution is high.
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