How to make a circuit on FPGA to run exactly at 2^28 MHz?

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blitzwing

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hi I have some questions.

I have designed a circuit (schematic editor) and I load it into an FPGA (Cyclone II).
The problem is that I want the circuit to run exactly at 2^28 MHz = 268.435.456 Hz

I cannot use the FPGA's PLLs since their maximum output frequency is 250MHz.

I was thinking using a PLL that goes faster because there are no crystals , oscillators
that provide this exact frequency (2^28 MHz).

Is there any easiest solution?

Changing the FPGA device is not an option.
The frequency must be exact. (It's important).

Thanks in advance
 

clock fpga

you have only one easy option: change FPGA, sorry
 

how to use clock in fpga

FINALFANTASYFAN as I said I will propably use an external PLL.
The external PLL can provide the exact frequency(2^28MHz)?
 

400mhz + fpga

'coz u don't want to use another FPGA, I think it's the best option.

Added after 2 minutes:

PS @ ur question: I'm not sure but I think it's quite exact
 

fpga clock

you have to check, try the cypress pll.
maybe taht you can find what you need.
i think that you have to write a very good hdl code to work at 278 mhz.

G.
 

fpga, clock

If you need just a PLL why do you you need FPGA, for?? Also Even if you get PLL running so fast there is no way slower FPGA can process the data
 

fpga+clock

I am using the FPGA beacuse I have the circuit in it. The 250 Mhz is the maximum
operating frequency of the FPGA's PLL. The circuit can run with a clock up to 400 Mhz.

Propably i wont be able to run at that exact frequency so I guess I'll have to
change the design a little bit.

Anyway thank you all
 

fpga clock help

Another option, you could buy a custom clock oscillator. Some crystal companies sell custom-cut fixed-frequency clock oscillators that aren't too expensive even in quick prototype quantities.

Or maybe buy a programmable oscillator, if you don't mind the additional phase jitter. I've seen a few units that go over 250 MHz, usually with LVDS or LVPECL outputs. One example is the Cardinal CPPHV. I haven't tried them.
https://www.cardinalxtal.com/products/fipo.htm
 

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