maybe you could rephrase your question, as it does not make any sense to me.
If you have a vco that has a tuning range of 0 to 3 volts, and you connect it to a modern PLL chip with a charge pump output, with that PLL chip running off of say 3.3 V DC, then the PLL phase detector will automatically put out a voltage between zero and 3 volts to try to lock up the VCO. You DO need a loop filter between the phase detector output and the VCO tune input because the control loop gain and phase shift vs. frequency needs to be set to make the control loop stable.