Re: Clock limitations on AD9528 not clear

I have a further question which is related to this matter.

I am using ADIsimCLK v1.70 to verify my proposed set-up for the AD9528.

I end up having a frequency of 1.28906GHz at the output of M1 (VCO freq 3.86719GHz, M1 = 3 (some small rounding errors)) which results in the error "Max M1 out freq is 1.25GHz". I cannot find an explicit reference to this limitation in the datasheet.

I plan to divide this down using the 8-bit channel dividers in the clock distribution part to be less than 1GHz at each output.

Is this an error in ADIsimCLK?

Should the limitation be placed after the channel divider (as per your reply)?

Is there a maximum frequency that the 8-bit channel dividers can be run at?

I have just noticed that this is actually explained here (Query in AD9371 Evaluation Board  VCXO selection doc ).

I assume this is just a bug in ADIsimCLK. Can you please confirm?

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  • Yes. Even when all of the 8 bit dividers are configured to output low frequencies, simCLK reports that "Max M1 out freq is 1.25GHz".

    This resolves to 2 questions which are not specified in the datasheet.

    What is the maximum frequency that the 8-bit Output dividers can be run at?

    What is the maximum output frequency of the M1 divider?

Reply
  • Yes. Even when all of the 8 bit dividers are configured to output low frequencies, simCLK reports that "Max M1 out freq is 1.25GHz".

    This resolves to 2 questions which are not specified in the datasheet.

    What is the maximum frequency that the 8-bit Output dividers can be run at?

    What is the maximum output frequency of the M1 divider?

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