Hi,
On the HMC835 evaluation board (https://www.hittite.com/content/documents/eval_pcb_schematic/hmc835lp6ge_eval_pcb_schematic.pdf) the loop filter contains a resistor R58=510R between last RC filter stage and Vtune input.
The resistor does not appear in the datasheet.
Can you explain the role of this resistor?
Regards,
MAS