通信工程文献翻译——关键词: MCU;信号发生器;相位累加器;DAC

摘要: 它的优点，使用DDS芯片输出信号的频率更大，精度更高，但用户不能改变输出信号的波形。MCU可以产生所需的任意波形，但其程序执行的顺序限制速度。因此，我们利用它们之间的协同设计数字控制信号发生器。该系统的优点是输出质量好的精度和稳定性，波形，频率和高频率的，空的振幅和相位是步入需要。

介绍

数字合成的正弦波形是一种公知的方法已被应用到许多嵌入式应用[1]。这种技术可以用来创建一个积极的数字正弦波形。其它频率合成方法相比, 直接数字频率合成器一直以其优良的特性在现代频率合成技术中最流行的趋势。DDS技术实现信号源，可以进行精确控制DDS的频率，程度，相输出波形的数值控制电路等,系统利用这种方法有许多优点，如安定，可靠和准确度。

商业DDS芯片只能导出一个正弦波因为ROM表中的数据形式已经被凝固。如果需要进入任何波形，它可能会真正的由FPGA采用DDS的IP核或硬件描述语言等方式来实现，然而, 这种方式成本费用高;另一方面，可以任意波形通过开展数字频率结合使用的微控制器单元（MCU）和DA转换实现。实验和应用测试表明，数控信号源所组成的STM32微控制器和DDS芯片可以很好地工作。

数控信号源系统设计分析

系统使用STM32作为控制核心和AD9850作为发生器。STM32是基于ARM的32位微控制器与128 K字节的闪存。

STM32的两个信号输出，可以实现同时通过控制AD9850的和DAC0832输出。该系统的设计的框图如图1所示。一个信号输出通过控制AD9850，可产生30 MHz正弦波和矩形波，其他输出的任意波形及其频率低于10千赫是通过频率数值混合器DAC0832产生的。

硬件设计

AD9850的模块

AD9850包含DDS系统和高速比较器。 AD9850可以实现对整个数字频率相结合。可编程的DDS的核心是相位累加器，它是由ADR和一个N位相位寄存器组成，N为24?32。

连接到精确的时钟源和写入频率相位控制字后，AD9850的可以产生可编程频率和相位可编程的模拟正弦波输出波，这可以......

Keywords:Signal generator; Phase Accumulator; DAC

Abstract. The MCU can produce the required arbitrary waveforms, but its program execution of the order limit the speed.So we use their Synergy to design the digital controlled signal generator. The System has the advantage of output good quality waveform, frequency of precision and stability ,and high frequency, empty, amplitude and phase is to step into the need.

Introduction

The digitally synthesized sine waveform is a well-known method and has been applied to many embedded applications [1]. This technique can be used to create a positive digital sine waveform. Compared to other frequency composing method, Direct Digital Frequency Synthesis has been the most popular trend in modern frequency synthetic technique for its excellent characteristics. The signal source that the DDS technology realizes can carry out accurate controlling on DDS frequency , extent , phase exporting wave form's etc. by numerical control circuit, the system making use of this method has many merits such as stability, reliably and accuracy.

The commercial DDS chip can only export a sine wave for the data in the ROM form already has been solidified. If needing to come into being any wave form, it may come true by the way that FPGA adopts DDS IP core or hardware describe language etc, however,the cost of This way cost is high; on the other hand, any wave form can be achieved by making use of micro controller unit (MCU) to carry out figure frequency combining and DA converting. The experiment and applying testing have shown that the numerical control signal source composed of STM32 micro controller and DDS chip can work well......