question on comparator

[xz781122]

i am reading the book 'CMOS analog circuit design'written by Allen.on the page 457 table8.22.why all the CMOS is in saturation when comparator's parameters are calculated.In my opinion the CMOS in second stage must be in triode rigion.

 

[aryajur]

Could you attach the table and diagram?

 

[surianova]

the second stage should be saturation. You cannot get full swing or rail to rail
in second stage. You need a buffer or double inverter to get a full swing

Suria

 

[sunking]

pay attention to you input voltage, what is the value of vcm?
make the |vcm|>0 and try

 

[huangjw]

I think a comparator is a special OP-AMP,the linear rigion is very small, the output's middle point often made all MOS operate in suturate rigion, so you can use this characteris to calculate the comparing threshold voltage.

 

[tecsiun]

it can be used to modify the input and output impedence.