PLL loop filter selection

bandpass

As we know, the number 1 LPF in schematic is the well known circuit.
  A/ t: m% {" G/ r+ V" W
   But some application is like the number 2 LPF in schematic. Any commetions about it ?

' e0 _+ e) R* s/ y   Any discussion is appreciated.

circuitman5566

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