Big question in folded cascode with CMFB ?

[wael_wael]

Hi everybody
i am new in this area and my back ground in communication, so i am not expert in IC design.
now i have problems with this circuit
https://img45.imageshack.us/my.php?image=untitled6aa.png
could any one help me to find the
VB1--VB2--Size of M15--M16
and for CMFB which one optimum choice for pipADC?
continuous time one or swich capacitor one.
Best regards

 

[wael_wael]

i hop one of you can help me
thanx

 

[airboss]

Hi,

As for the choice of VB2, VB2 = Vov_M10 + Vgs_M12 = Vov_M10 + Vov_M12 + Vth

If M10, M12 have the same length, they would have the same Vth.

VB1 depends on the current flowing through M6, Vov_M6, Vov_M4, Vth_M6. I guess you just need to play with the equation of current in saturation region, then you can find VB1.

 

[wael_wael]

ok thanks
what about the size of m15 M16