ICMR--- is it need to test the current of the MOS(TAIL)

[poweric]

i want to know
when i want to test the ICMR , it need to connet the 1_gain structions
when the VIN arise measure the VOUT in the linear regions
is it also to measure the I(TAIL) make sure it opeartion in the saturation region??????

 

[raduga_in]

I hope your case is of simple NMOS source coupled pair .
Here, the minimum value ICMR decides at least the turning ON of the source couped transistors and maintain the
required headroom for the tail current source transistor ..

 

[poweric]

how i think of the headroom as your mentions
when it is enough to drive the input PMOS into SAT if the MOS of tail current is liner region as the curren source
the case can be condsider the ICMR region??

 

[hung_wai_ming@hotmail.com]

The point at which tail current drops from the flat line during both input voltage tied at one point and changes its input voltage, is where the point min ICMR is, for a typical NMOS sourced coupled pair op-amp