Can anybody explain me what is the task of the Low Pass Filter in PLL ?​

Every were that I search I find only a short and general answer that said that the LPF give the control voltage to the VCO​

o.k. but why actually use LPF ?​

What is especially in LPF ?​

 

Can anybody explain me what is the task of the Low Pass Filter in PLL ?
Every were that I search I find only a short and general answer that said that the LPF give the control voltage to the VCO
o.k. but why actually use LPF ?
What is especially in LPF ?​

The primary function of the LPF is to control loop bandwidth and to give the loop stability. Secondarily, it removes high frequency components which may be created by the phase detector, which could otherwise contribute to phase jitter on the output.