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ADF4158 reference spur

Question asked by mcluka on Nov 4, 2013
Latest reply on Nov 5, 2013 by rbrennan

Dear rbrennan,

I have designed a ADF4158 (passive filter) with HMC358 as VCO and VT-501 (10 MHz) as a reference (cmos output). Everything looks quite as simulated in adisim, but I noticed random "running" spurs at 5800 MHz, around which was alrady descused on forum. I changed frequency to 5799 MHz and spurs were gone. Other thing that is bothering me is reference spur at 10 MHz of carrier, which is -60dBc. Is there a way to reduce this spur. I also have am ADF4158 evalboard, where I do not see those spurs. Maybe because the reference on the evalboard has not that high peak-peak voltage output as mine?

Thank you in advance for any advice, Luka

ref_spur.gif

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