基于DDS技术的频率合成源设计

直接数字合成（DDS）是一种重要的频率合成技术，采用该技术产生的信号，具有频率转换速度快、频率分辨率高、频率稳定度高、相位变换连续、相位噪声低、集成度高、易于控制及性价比高等多种优点，可用于各种对信号频率的性能指标要求高的场合。详细介绍了高性能DDS芯片AD9858的基本原理和结构特点，以及单片机PICl8F442芯片的结构、性能特点和相关接口电路。描述了利用该芯片作为核心芯片组成频率源的全过程，包括设计原理、硬件电路和软件设计的主要流程图。

Design of Frequency Synthesizes Source Based on DDS Technology

It is a kind of important frequency synthetic technology that the direct figure is formatted(DDS),adopt the signal that this technology produces,the conversion speed of frequency is fast,the resolution ratio of frequency is high,frequency is steady degree is high,the phase varies in succession,the phase noise is low,the integrated easy,easy to control and the cost performance is low,etc.It can used in various kinds of to signal performance occasion that index expect much of frequency.This text has introduced the basic principle of high-performance DDS chip AD9858 and structure characteristic in detail,have described that utilizes this chip to make up the whole course of the frequency source as the key chip,including design principle, hardware circuit and main flow chart of software design.