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ADF4351 - Measuring VCO output phase noise

Question asked by jsuss on Nov 20, 2015
Latest reply on Nov 20, 2015 by rbrennan

I am trying to characterize the phase noise of the VCO output on the ADF4351 eval board. I am looking at frequencies that don't already have phase noise plots given for them in the data sheet. How do I go about performing this procedure?


Currently to solve this issue, I removed one of the resistors in the PLL (connected to VTUNE) and hooked up a power supply to VTUNE and GND in the attempt to manuallly tune the VCO to the frequency I want. I am having trouble tuning to the frequency I want. Looking at the chart below from the datasheet:

I am trying to move between bands and have not been able to successfully do that yet. Am I approaching this problem wrong?