PFD in PLL, Lowpass or bandpass?

PLL acts as a narrow-band tracking filter, so it can be seen as a bandpass filter centered at its input frequency.
But transfer function of the input of the PFD is a low pass function with DC gain equal to 20log(N/Kpd).
So I am puzzled . lowpass or bandpass?

Simply the PLL has low pass c/cs with respect to the reference, i.e. when u draw the PLL closed loop response ur 0Hz is the reference frequence. So it is low pass with respect to the reference frequence and band pass with respect to the real frequency range.

I like this questions!

The story is exact in between. The PFD have two registers with an asynchron reset. One is feeded by the reference, the other by the divided VCO. The asynchron reset of both registers is triggered if UP and DOWN are active.

The question is interessting if you want to know how much phase noise the PFD contribute to the closed loop PN. Normally both registers are equal. The reference register contribute by a PLL lowpass function, the other by the PLL error transfer function or bandpass. The feedback path, sometime delayed for longer minimum pulses, does not contribute to PN.