Why is the differential VCO usually used in PLL?

[banid]

Why is the differential VCO usually used in PLL?

If we don't need the even multiphase outputs, I think the single ended VCO can be used. But, in most of papers, the differential type VCOs are used.

Why is the differential VCO usually used in PLL?

 

[nandu]

differential vcos are very resilient to power supply and ground noise

 

[zyyang]

you can get a better phase noise and more wide vctrl to improve the PN.
there is a PHD thesis whose auther is zhangwen tang ,the name of the thesis is called<< LC voltage controlled oscillator>>

 

[pfd001]

you can also use single ended VCO. you can search it in google to find single ended VCO

 

[cmos_dude]

you can also use single ended VCO. you can search it in google to find single ended VCO

YOu can use single ended VCO's , but they are a lot more susceptible to noise when compared with the differential VCO's
The differential VCO's have noise rejection qualities and they also provide you more control on the output freq, along with a wider tuning range.
But on the contrary, designing a differential VCO is much tougher that designing a single ended one.