PLL loop filter selection

bandpass

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

' W9 C. X6 g! d7 O: @* A" e   But some application is like the number 2 LPF in schematic. Any commetions about it ?

  s: h+ Z2 \: `   Any discussion is appreciated.

circuitman5566

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