QVCO using cascode structure

[wccheng]

Dear folk,

I just designed a QVCO using cascode structure with PMOS on top as current source. I find that the bottom of 4 mos (propagate signal in-between two differential VCO) could not enter the saturation region. Actually, do these four mos must working in saturation region?

thanks

wccheng

 

[psmon]

If the QVCO is oscillating, the MOS are switches. No need to be in saturation region.

 

[wccheng]

However, is it necessary to make all mos in saturation in DC analysis? Since my boss claim that.

 

[wccheng]

Anyone could answer this question? Since my boss always claim the DC operating point of all MOS should be in saturation first.
I have tried to make all MOS in saturation region in DC analysis. However, it could not oscillate. I don't know how could I explain to my boss because my boss always need to have explanation. I have told him that VCO is not need to be in saturation region when it is oscillating. However, he always claim it must be in saturation region in DC state.