Question about PFD digital signal in PLL chips

[liberal]

PFD in PLL chip

In the NS' PLL chip such as LMX2332,The PFD is digital,But my reference and VCO back signals are analog.How dose it work ?

 

[hanm]

Re: PFD in PLL chip

So,what's the differents betwen digital and analog signal if they all swing from vdd to ground.

 

[yibinhsieh]

Re: PFD in PLL chip

You can input analog signal into digital PFD. But the swing requirement for digital PFD is larger than the one for analog PFD.

Yibin.