Re: spur problem
I would suspect a grounding problem. You reference clock is leaking onto the VCO somehow. Being that it is 100 MHz, it should be fairly easy to fix, though. Make sure the pll is well grounded, make sure there are plenty of chip caps (0.1 uF, 4.7 uF) peppered around the circuit. Maybe you should isolate the power supply from the VCO by using a small (5 ohm) series resistor and then shunt caps very close to the VCO. Finally, you can make a simple R-C lowpass filter, with a cuttoff frequency of around 3 MHz, that should keep any possible 100 MHz glitches off the VCO tune line (one again, the C mounted as close as possible to the VCO).