500MHz clock distribution

[asrock70]

I have three separate PCB with DDS and need distribute clock 500MHz for them.
I thing lenght of every coaxial cable between clock source and DDS 20cm.
You tell me how to solve the clock source?
I looked at the clock buffers, but it's insanely expensive and poorly accessible.

 

[mtwieg]

For good high frequency clock distribution, you should expect some high prices. Look at companies like Cypress, Micrel, and Pericom as well.

 

[jiripolivka]

Everything depends on the 500 MHz source output and the output needed at each output end. If the loss of the power splitter is to be ~ 10 dB, you can use a resistor power splitter. For better power splitter, check "www.minicircuits.com", they offer low-loss power splitters with up to 32 outputs. Also reasonable prices and good products.
If you need an amplifier to reduce the distribution loss, the same company offers good and low cost amplifiers, too.

 

[mtwieg]

minicircuits makes great stuff, but they are quite expensive (from what I can tell their splitters are >$15 each). I'm assuming the OP wanted a buffer IC, not a passive splitter. Though there certainly are advantages to both approaches.

 

[asrock70]

Consent Minicircuit are rather expensive and things except ERA amplifiers are less accessible.
Just been looking for RF transformers Minicircuits and I have quite a problem with it.

 

[mtwieg]

You never said what kind of signal level your clock is. If you're putting it over coax I'm guessing it's a single ended square or sine wave? Most high speed clock buffers will have differential inputs and outputs, so you may require a balun transformer before the buffer input. For the differential outputs, you could just use one as a single ended signal, but the voltage swing will be small, unless you use another balun transformer.

Here are a couple relatively low cost devices:
**broken link removed**
**broken link removed**

 

[asrock70]

Thank you all for your help.
There was talk of a splitter from mini circuits.
They are very nice parts with us unfortunately not readily available and the price is also quite high.
You advise what topology can be built for low power splitter with small size?

 

[mtwieg]

Well a is about as cheap as it gets, but then you lose decent amount of power, so you'll likely need amplifiers somewhere.