what is advantage of this vco topology

[alex_fd]

hi,all the experts:
what is the advantage of this vco topology.there is a parallel combination of a nmos and a 1pF cap in series with the cross couple pair.what is the usage for this paralle combination of the nmos and large capacitor.thanks

BR

--- Updated Mar 9, 2022 ---

Is it to reduce the phase noise?

 

[betwixt]

Where does the supply feed the circuit? Center tap in the coil?

Brian.

 

[alex_fd]

yes.its supply feed the circuit from the center tap in the coil.