help on crystal oscillator design

[arsenal]

Thank you for your attention.
I have some questions on pierce crystal oscillator design,and eager for your help!
Can I use a CMOS transmission gate to act as the resistor? If not, then what are the disadvantages?
If I use an external resistor, then what are the disadvantages as compared to the usage of an internal resistor?

 

[E-design]

This is commonly done when operating on low supply rails. I mentioned this here

E