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.