QVCO using cascode structure

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

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

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

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.