基于DDS的高频率高精度信号发生器

为满足现代电子测量和无线电通信领域对激励源的需求, 采用DDS(Direct Digital Synthesizer) 芯片AD9854ASVZ 设计一款高频率高精度信号发生器。ARM Cortex-M3 内核的STM32F103VE 芯片作为系统的MCU(Microcontroller Unit); 在MDK-ARM 平台下用C 语言开发主监控程序和信号产生程序; 利用Python 工具在PC(Personal Computer)端编写人机交互界面, 通过串口实现PC 与MCU 之间通信; 设计低通滤波电路和多级放大电路对产生的信号进行噪声(杂散)抑制和幅度控制。测试结果表明, 该信号发生器输出信号失真小, 精度高,频率范围宽, 具备较好的稳定性。输出正弦波、方波的频率范围为DC ~150 MHz, 频率漂移100 PPB(Part Per Billion), 频率分辨率1 滋Hz, 输出信号幅度峰峰值可在10 mV ~20 V 范围内, 以10 mV 步进调节。技术指标满足大部分外场实验和工业应用的需求。

Research and Realization of High Precision High Frequency Signal Generator Based on Direct Digital Synthesizer

The high accuracy, high frequency signal generator based on direct digital synthesizer is designed to meet the demand of modern electronic measurement and communication system. The signal generation function is according to the AD9854ASVZ chip characteristic. Using STM32F103VE chip as the main controller, the peripheral low-pass filter circuit, multistage amplifier circuits, communication module, power circuit and so on are designed. The system software was programmed by C language and Python tools. Procedures are developed in C language to control signal and monitor process, using Python tools to implement visual interface. Based on the result of testing, the output frequency is from DC to 150 MHz, the frequency resolution is 1 μHz, the frequency drift is 100 PPB, the peak-to-peak value of output waveform amplitude is from 10 mV to 20 V. The system has advantages of simple structure, high precision and reliability, which can satisfy the demanding for the engineering application.