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Altera_Forum's avatar
Altera_Forum
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15 years ago

Clock doubler without PLL

I have a design where I need to double an incoming frequency but lo and behold I made a mistake of not putting this input signal in a dedicated clock input pad....

so, it would appear that PLL:s can't be used now so I'm wondering if anyone has any trick how to double a frequency perhaps just with RTL or some other means.

The FPGA is CIII.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    For a proper fpga based design, I am afraid the notion of doubling clock without pll will get you in a timing mess.

    Consider using the slow clock but use two processing channels (odd/even samples). Though a pain but should be equivalent. The problem would be at final crossover to double rate... This is equivalent to having a DDR approach inside fpga.
  • Altera_Forum's avatar
    Altera_Forum
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    Thanks. The most feasible way seems to be to add this on the list of changes for a new board spin so I can use a PLL.. I did some google search and didn't find anything either.