DDS频率合成器的方波重影现象研究

摘要

As the 3rd generation of frequency synthesis technology,direct digital frequency synthesis(DDS)is widely used in instrumentation,communication,radar and other fields. When a DDS-based frequency synthesizer outputs square wave,the waveform comes with double shadow obviously. The double shadow directly impacts the quality of the square wave. The reason of square wave double shadow occurs is analyzed. And an improved algorithm is proposed,which is suitable for FPGA. The new al-gorithm weakens the square wave double shadow effectively.%直接数字频率合成技术（DDS）作为第三代频率合成技术，广泛应用于仪器仪表、通信、雷达等领域。基于DDS技术设计的频率合成器输出方波时，存在明显的重影现象，这直接影响了方波的质量。对方波重影出现的原因进行了分析，并提出一种适用于FPGA的改进算法，较好地弱化了方波重影。