Multy RF Frequency Signal Source's Design And Achievement

The technology of direct digital synthesizer (DDS) are widely used in recent years,with the development of digital circuit and enlarger of scale of IC, the function ofdirect digital synthesizer (DDS) are stronger and stronger, simplyfier to use, it'scontrol function are perfect. The AD9858 is a direct digital synthesizer (DDS)featuring a 10-bit DAC operating up to 1GSPS. The AD9858 has 4 32bitfrequency_control_registers, complete high frequency synthesizer capable ofgenerating a frequency-agile analog output sine wave at up to 400+ MHz. TheAD9858 is designed to provide fast frequency hopping .The development of embedded system make people achieve complex function inmore smaller room, and can easily change control mode ,control logic, in order toupdata system easily and rapidly. The Texas Instruments MSP430 series is anultralow-power microcontroller family consisting of several devices featuringdifferent sets of modules targeted to various applications. It has JTEG interface caneasily down load program and debug.The software support compiling in c languaregeentironment,make the program has efficient code .The technology of direct digital synthesizer combined with the embedded system togenerate a new method of producing analog signal,it's character is convenience andagility,easy to updata and produce agile wave form. The development of digitaltechnology give us a new way to process analog signal,using digital technology tocomplete analog signal source is very important.This article introduced using the newmethod to achieve analog signal souce system,broadly introduce the method ofgenerating signal,modulation and controling ,as well as the processing of EMIproblem.This article introduced using the MSP430F149 as the centre unit ,expand key boadand display module,and analog control cirduit,to control the dds generate the fourfrequency, through multy grade power amplifier, to achieve four frequency signalsouce.In this article, the writer use the gal achieved the combination of pulse,in order tocontrol the RF power ,and concatenat with external concatenatal signal.This article introduced using PIN diode achieve controled attenuater to continouslycontrol the RF power.