Based On The Ad9857 Arbitrary Waveform Generator Design

Signal generator is one kind of important instrument in modem electronic ones. With the close combination between the electronic measurement and computer technology, a new signalgenerator-----arbitrary waveform generator emerges as the times require. It has expansiveapplication and development foreground because it can generate any complicated arbitrary waveforms defined by users ,. The time to develop the Arbitrary waveform generator in our contruy is quite later than those advanced contruies ,at the same time the development of the applicable production is very slow.At present, it is a urgent task to make arbitrary waveform generator with high performance.Therefore, the development in makeing arbitrary waveform generator has a abroad and far-reachingmeaning for promoting the development of virtual instrument and it has been a new problem to make the deeper research in the field of measurement.Direct digital synthesizing is a new frequency synthesizing technology,which adopts phase increment controlled by digital .It has so many virtues such as high frequency relution ,fast frequency switching ability,continuous phase ,low phase noise and integration easily for its numberic operation that has been adopted widly.After having analysed projects of waveform generator ,1 have designed a kind of applied aribrary waveform generator with the cbrief structure and excellent performance adopting DOS ,which is based on the Anolog Device company's DDS chip-AD9857 according the target system. I has mainly discussed the sofeware and hardware of aribrary waveform generator controlled by the microcontroller in my With the control of the high proformance microcontroller-80C196KC, this instrument builds up the main circuit adopting single tone and DAC of AD9857.In my project,I .have designed some special circuits with the advanced method of EDA (Electron design automation)based on VHDL and CPLD.It can produce standard waveforms such as sine,square,triangle,and generate aribrary waveform according to the user's demand,at the same time,it has the ability to produce the amplitude modulation signal based on the carrier of sine and the aribrary waveform.It has wide frequency width and high frequency relution.The maximum output frequency can get to 80M and the highest frequency relution can get to 1 u Hz,the waveform memory is 64k..It has the important reference value for three classical structures-PC bus card,stand alone,VXI module.