SNAS722A December 2017 – October 2018 LMK61E07
This spur occurs at an offset equal to the difference between the VCO frequency and the closest integer channel for the VCO. For instance, if the phase detector frequency is 100 MHz and the VCO frequency is 5003 MHz, then the integer boundary spur would be at 3-MHz offset. This spur can be either PLL or VCO dominated. If it is PLL dominated, decreasing the loop bandwidth and some of the programmable fractional words may impact this spur. If the spur is VCO dominated, then reducing the loop filter will not help, but rather reducing the phase detector and having good slew rate and signal integrity at the selected reference input will help.