Source for PLL input frequency

[vinod488]

Hi,

I hav a basic doubt relate to crystal frequency.

I am designing clocking structure in Soc.
If we connect Crystal directly to input of PLL it will generate reference frequency or we have to provide extra oscillator in between crystal and PLL.

Thanks in advance,

Vinod

 

[xiaorui2007]

We need to provide extra oscillator to generate reference frequency.
Only one crystal can not oscillator.

The oscillator circuit is not complex. Simply it can be implement with one INV, one crystal and two capacitors.

 

[nanda_kishore]

If it is a complete crystal oscillator module, you are referring to.. then there is no need of another osc. you can directly connect it to PLL input.

 

[khouly]

the crystal it self is not an oscillator , so u can't connect it to the input of the PLL , u need a crystal oscillator to use crystall as the resonator , and the output of the crystal oscillator will be the input of the PLL

khouly