Will the ADF4159 reference doubler work with reference inputs of 250MHz? I have a low phase noise 250MHz signal and I would like to use it as a reference for the ADF4159. Additionally I would like to optimize the phase noise of the PLL system, so would like to use the PFD at 100MHz. Can I double the 250MHz reference to 500MHz and then divide by 5 to get to 100MHz PFD frequency? By the way my evaluation ADF4159 on your eval board does not seem to let me do this. Is this to be expected? What's a sensible way to optimize the phase noise of my system? Just use the 250MHz reference and divide by 3 to get to an 83.3MHz PFD frequency and not use the doubler?