Peak detection comparator simulation problem.(Process and no VSS version)

Here is a peak detection comparator schematic and simulation,i have three question about them.

1.Why is there a high signal in C point,but not in A and B point?

2.There is VSS in this peak detection comparator schematic,is there a peak detection comparator schematic without VSS in it? I connect it with gnd,but the wave is wrong.

(1) peak detection comparator schematic

(2) peak detection comparator simulation

The purple line is the $V_{PZT}$,and the blue line is the $V_D$,the red one is the output of comparator,that is ,$V_{CP_PK}$