本文介绍了dds的原理以及altera公司的fpga器件FLEX10K系列的主要特点，给出了用EPF10K40实现直接数字频率合成器的工作原理、设计思路、电路结构和仿真结果以及功能改进。-This article describes the principles dds and altera fpga device company FLEX10K series of key features, is given with EPF10K40 the direct digital frequency synthesizer operating principle, design concept, circuit structure and the simulation results and functional improvement.