一种基于DDS的函数发生器

Direct digital frequency synthesis function generator

针对综合测试仪的函数发生器模块的高集成度和低成本的要求,设计了一个通过现场可编程门阵列(FPGA)实现直接数字频率合成(DDS)数字部分的函数发生器。它由微处理器系统、DDS系统、模拟通道3部分组成;在FPGA内部设计了相位累加器和ROM波形存储表,通过加载频率控制字改变波形频率,实现了DDS系统的数字部分,采用W77E58单片机作为函数发生器的微处理系统。测试结果表明,设计的函数发生器输出的正弦波、方波和三角波完全满足项目对波形幅度、频率、精度等指标的要求。

Aiming at high integration and low cost requirements at function generator module of integrated test instrument,a digital function generator was designed based on the direct digital frequency synthesis（DDS） technology.It consisted of three parts-microprocessor systems DDS system,analog channel.Phase accumulator and the ROM stores waveform table in field programmable gate array（FPGA） were designed,to change the wave frequency by load frequency control word,to achieve the digital part of DDS system,and the MCU of W77E58 was microprocessor systems of the function generator.The test results indicate that the design of the function generator can produce sine wave,square wave and triangular wave,and accords with the system requirements on the waveform amplitude,frequency,precision of the indicator.