I have three separate PCB with AD9954 and need distribute clock 400MHz for them.
I thing lenght of every coaxial cable between clock source and DDS 20cm.
You advise me how to solve the clock distribution?
In doing the clock distribution, you need to consider the following parameters:
1. Differential or Singe-ended Input
AD9954 has a differential input (Pins 8 & 9). So, you might want to consider using a balun transformer if you need a single-ended input. Our eval boards uses the balun from M/A-COM Tech Solutions (datasheet) so you might want to start with that.
2. AD9954 input level
The AD9954 accepts maximum REFCLK input voltage swing of 1Vpp differential. So, it all goes down to your 400MHz REFCLK source. Since you have 3 boards, you need a power splitter. Resistive splitters have an advantage of a wide bandwidth but the loss is great. So, you might want to consider other splitters. Here's an application note from mini-circuits about power splitters. If the output of the splitters are very small due to insertion loss, you can then use an amplifier to boost it up.
Hope this helps.
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