高性能数字频率合成器的设计与实现

Design and Implementation of a High-Performance Digital Frequency Synthesizer

通过对直接数字频率合成技术的研究,采用单片机AT89S51控制DDS芯片AD9854设计出一种高性能直接数字频率合成器。该数字频率合成器采用并行通信的方式传输控制字,通过改变控制字来改变输出频率,得到所需频率的正弦波。软件上采用菜单式、全部键盘控制方式。用4×4矩阵键盘控制,进行功能选择以及设置频率、幅度和相位控制字。界面显示用带中文字库的液晶TS-12864显示,实现了良好的人机交互,系统操作使用方便。用单片机控制DDS数字芯片实现的数字频率合成器,有着比模拟频率合成器更好的抗干扰性、频率分辨率和频谱纯度,同时有着更小的体积。系统经测试得到所需频率的正弦波,数字频率合成器设计成功。

After making research on the digital frequency synthesis, a high performance direct digital frequency synthesizer （DDFS） was designed by using a single chip microcomputer （SCM） AT89S51 to control the DDS chip AD9854. The digital frequency synthesizer uses parallel communication to transmit control word, and the sine wave of the right frequency can be gotten through setting the control word to change the output frequency. On the software, the menu type and complete keyboard control mode were used. With the 4 × 4 matrix keyboard control, DDFS carries on the function choice as well as the establishment frequency, amplitude and phase control word. Display interface uses the Chinese character liquid crystal display （LCD） TS- 12864, achieving a good human-computer interaction and a user-friendly operating system. DDFS, which is realized by using SCM to control digital chip DDS, has better anti-interference, frequency resolution and spectral purity than a direct analog frequency synthesizer, and the smaller volume. The sine wave of the frequency for need was gotten through the system test, and digital frequency synthesizer was successfully designed.