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Building a circuit which involves with a AD9854 DDS

  1. Jun 7, 2007 #1
    Hi Guys..

    I am try building a circuit which involves with a AD9854 DDS(Direct Digital Synthesis) chip to generate a frequency controlable sine wave for me...

    The problem for me is that the Master clock supply for the chip need to be around 200MHz...I don't know whether there is any crystal oscillator that can perform this function...or maybe there are some CMOS programmable oscillator chips that can do the trick for me...?

    Here is the link of the chip:
    http://www.analog.com/en/prod/0,2877,AD9854,00.html

    Thank you guys for ur help!!
     
  2. jcsd
  3. Jun 7, 2007 #2
  4. Jun 7, 2007 #3

    berkeman

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    Staff: Mentor

    On page 30 of that datasheet, it says that you can put in as little as 15MHz, which is definitely available in canned oscillator form. I'd stay away from messing around with anything over about 50MHz, unless you are making your own PCBs and understand stripline transmission line techniques.
     
  5. Jun 7, 2007 #4
    HAHA! I made a lot of the plots that are in this datasheet when I was a co-op at Analog Devices ~10 years ago!!

    The internal clock on the AD9854 needs to be at least 20Mhz. There's a built in PLL multiplier, so the external clock source that you supply can be as low as 5Mhz. You just have to enable the multiplier, and set the bits appropriately (see pages 30-31).

    as low as 15Mhz and still achieve 300Mhz internal clock. The internal clock can run lower than this as well.
     
  6. Jun 7, 2007 #5

    berkeman

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    Staff: Mentor

    Thanks asynchronous13, and welcome to the PF. It must have been way cool to work at AD as a co-op! Where are you now?
     
  7. Jun 8, 2007 #6
    i ran 100's of these parts through FFT's for characterization while i was there. Analog Devices was a great place to work, but they didn't give me enough to do as a co-op, so i ended doing stuff like designing/building guitar distortion pedals for personal use :-)

    10 yrs in summary: BS in EE from U of Tennessee -> Harris Corporation in FL (worked on international space station and Comanche helicopter) -> France for grad school, got a french EE degree -> masters in EE from GaTech (DSP) -> currently in Atlanta at GaTech working on PhD in unmanned aerial vehicles
     
    Last edited: Jun 8, 2007
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