how the charge pump output current convert to voltage?

hello,
how the charge pump output current convert to voltage if the loop filter is a passive loop filter?Thanks!

The charge-pump converts the digital pulses into an analog current that is converted to a voltage via the passive loop filter network.
The use of a charge pump adds a pole at the origin in the loop transfer function of the PLL, since the charge-pump current is driven into a capacitor to generate a voltage which drives the VCO.

just use the sink and source current to charge and discharge the Cap!

PFD detect the width of pulse to control the sink and source time~~