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I need a clock source for some data converters (DAC, ADC), and I would like the clock frequency to be as configurable as possible. I assume this would involve some kind of clock multiplier/divider, PLL, etc. The range of frequencies I would like to be able to configure at runtime would be something like 200ksps up to about 20Msps (one clock cycle per sample). I don't need extremely tiny frequency steps in this range.

The ideal answer would reference specific part numbers with detailed reference designs. I can deal with single ended or differential clocks. Configuration of the clock generation would most conveniently be with 3.3v CMOS logic, though level translation is certainly a viable option there.

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  • \$\begingroup\$ Requesting specific products is off-topic for StackExchange. However, I think your question, for the most part, fits. \$\endgroup\$ – DoxyLover May 20 '16 at 2:16
  • \$\begingroup\$ No specific PN's, but check out SiLabs. \$\endgroup\$ – The Photon May 20 '16 at 2:20
  • \$\begingroup\$ Is there a reason that you can't just sample at 20 Msps, and then decimate afterwards? \$\endgroup\$ – The Photon May 20 '16 at 2:21
  • \$\begingroup\$ @The Photon - memory bottlenecks to some extent, processing capabilities to a greater extent, unnecessary added complexity of multirate signal processing algorithms (compared to no processing). Power could be a factor, but i think it's probably not in this case. It's an interesting thought that I will think about a bit more. \$\endgroup\$ – bean May 20 '16 at 3:11
  • \$\begingroup\$ If you want 'cleaner' data certainty then it pays to over-sample by 4 to 16 times, then take the average of the samples. It really gets rid of jitter and spikes. If you can manage that in your design. \$\endgroup\$ – Sparky256 May 20 '16 at 3:38
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What you are looking for are called "programmable clock generators", as your title says (do a google search for this). These are typically self-contained oscillators with a programming interface and, often, multiple voltage outputs, and single-ended and diffential outputs. 200KHz to 20MHz with 3.3V output should be easy to find. Other characteristics to check out include jitter and stability.

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  • \$\begingroup\$ I agree with the "programmable clock generators". The less parts on the board, the cleaner the clock signals will be. \$\endgroup\$ – Sparky256 May 20 '16 at 3:50
  • \$\begingroup\$ Ugh, seems I was closer to what I was looking for than I thought... \$\endgroup\$ – bean May 20 '16 at 15:57

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