AD9852 can be used as frequency source for FPGA or not？
It's entirely possible, though you should test the performance is sufficient and provides what you are looking for.
I want to use it to generate the clock, and use it to be the system clock of FPGA(like xilinx and so on), the reason that I use AD9852 is I want to generate a varibale clock, I only get this method. Or do you have any good idea to generate a variable clock? for 100K to 100MHz, and the step can be very small?
Generally I would expect DDS to be a fine solution for generating a clock for an FPGA from a jitter performance perspective. Given the range of frequency you are looking to support, DDS is probably the best solution. AD9852 should be a very good fit for this. If you use a sample clock of 300 MHz, then you can get steps as small as 70 milliHertz - I consider that very small, hopefully it is small enough for your needs.
Thanks a lot for your quick answers.. I not only need the small frequency, but also a large one, large to 100MHz, and the step as small as possible. so is it still a good choice to use a DDS, like AD9852?
Thanks a lot for your help.
With a 300 MHz sample clock, you should be able to get up to ~120MHz while still keeping the reconstruction filter design relatively easy.
Ok, I get it. so DDS is the best way to get a wide range clock...Thanks. Another question, it is better to use AD9852, because it has a comparator into it? I can connect the Iout(the sine output) to the comparator input easily, if I use another DDS, I have to use a comparator outside to convert the sine or cos to square waveform, am I right? Do you have more DDS to recommend?
Yes. There are other DDS devices with the comparator on board as well that would be perfectly good options. AD9852 is somewhat old (designed nearly 20 years ago). AD9952 and AD9912 would be newer devices that also have a comparator.
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