关键词: 直接频率合成, 相位截断杂散, 相位码补偿, MATLAB仿真, 现场可编程门阵列（FPGA）

Abstract: This paper introduces the principle of Direct Digital Synthesizer（DDS） system with phase truncation, and expatiates on the source of phase truncation spur by analyzing the mapping from phase to sine-amplitude. On this basis, the paper analyses the optimization calculation length of truncated phase code founded on high frequency resolution and lossless compression of sine-wave, and a method of compensating error of phase code before phase truncated is proposed to implement DDS system without phase truncation spur. The validity of method is verified through simulation by MATLAB and implementation on a FPGA chip.

Key words: Direct Digital Synthesizer（DDS）, phase truncation spur, phase code compensation, MATLAB, Field Programmable Gate Array（FPGA）