AD9959 Board

Board Layout



The DDS board contains either an AD9958 (2 channel DDS) or the AD9959 (4 channel DDS).  The board also contains power supply regulators, 4 250 MHz Low Pass Filters, and 4 high speed comparators.  The clock is provided by a 125MHz clock osc.  Sinewave outputs are also available from just before the comparators.
    This board has been built and tested.  I  was able to overclock it to 750 MHz(the specis 500MHz)!  A second set of prototype boards has been produced.

I currently have no more AD9959 boards. I finally got a 300 MHz oscilloscope and was able to look at the outputs. I found on my prototype board that the 2 squarewave outputs goning through the LT1715 comparators have crosstalk. Unless they are on the same freq. the outputs interfer with each other. This is only true of the digital outputs in each pair(ie ch 0 and 1 affect each other but not channels 2 and 3). Also, the analog(sine) outputs all seem OK. I believe the problem is a layout problem and/or power bypassing. The next run of boards(after my 995x project) will be ported over to KICAD. At that point, I will improve the layout around the LT1715's per the LT1715 Data Sheet.