I would like to know the set up for measuring Gain and Phase plot for the charge pump PLL .I tried breaking the loop after the Divide by counter and giving a voltage source with VDC=0V and Vac=1V & tried to take measurements using spectre .But this did not work fine .could someone let me know the setup for plotting gain and phase plots .
the best is to make a truthful model of your pll. Then it is easy to simulate the frequency responce. After that you can do a transient analysis of the actual schematic