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HMC 835 spur

Question asked by bigbig on Apr 18, 2018
Latest reply on Apr 19, 2018 by dyoung1

When we make  HMC835 output frequency 2G~4G,there are some  regular spurs. For example, when the output is 2500M,2005.05M,2005.1M...., the spur can observed near the main signal  with the 300kHz Spectrum analyzer bandwidth,howerver when the output is 2005.01M, 2005.02M, 2005.03M, 2005.04M....there is no obvious spur 。

So the spur exist when the output is the mutilples of the  50K (about 70dBc),  but  the mutilples of the  8M don't exist   obvious spur.

 we use the internal VCO and HMC mode, fractional mode.   the PD is 51.2M,the frequency step is 10K.

I want to know the reson of this phenomenon and how to config the register to cancel the spur at  the mutilples of the  50K.

if you want to get the picture about the output with spur, i will sent to you.