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HMC439 with mixer and AD9914

Question asked by pichonro on Apr 14, 2015
Latest reply on May 18, 2015 by pichonro

Hello,

I have a prototype with a HMC439 like attached image.

I added a mixer and an AD9914 DDS before the dividers.

My problem is when the output frequency is near integer values, I have big spurs.

For example, when I set 5500.1MHz, I have 5500.1MHz carrier and +/- 100KHz spurs.

I don't understand why I have spurs because the PLL works with integer values and DDS for fine values.

Thanks in advance for your help.

Best Regards.

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