PLL loop filter selection

bandpass

As we know, the number 1 LPF in schematic is the well known circuit.

! W. x6 x2 d  r4 |% S+ `, v+ t+ ?   But some application is like the number 2 LPF in schematic. Any commetions about it ?

   Any discussion is appreciated.

circuitman5566

thank you so much! thank you so much! thank you so much!