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What is Max Generated clock freq for AD9850 - REF/2 or REF/3 ?

Question asked by borisf on Jan 4, 2018
Latest reply on Jan 4, 2018 by borisf

Dear Forum.

 

The Datasheet for the AD9850 says in the opening paragraph that :

 

"The AD9850’s circuit architecture allows the generation of output frequencies of up to one-half the reference clock frequency (or 62.5 MHz)"

 

Later it refines that to:

 

"To apply the AD9850 as a clock generator, limit the selected output frequency to <33% of reference clock frequency, and thereby avoid generating aliased signals that fall within, or close to, the output band of interest".

 

 

We would need a 62.5 MHz top end frequency to use as an internal clock  - if we do that :

a) how badly affected would the generated clock be ?

b) any recomendations to work around this - are there best practice for filtering etc that you could recommend ?

 

Alternative is that we always use a lower clock frequency and use an FPGA PLL to scale it 2x.

 

Many thanks !

 

boris.

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