inherent commom mode feedback

[srimatresri]

can any one explain the inherent common mode feedback in the following circuit

 

[pavel_adameyko]

Hello)
Why the dimensions of Mp4 are l=5.2u and W=3u ?? Shouldn't it length be 0.13 um like others?

 

[FvM]

Shouldn't it length be 0.13 um like others?

Yes, otherwise the marking "I2" for Mp4 won't be correct.

can any one explain the inherent common mode feedback in the following circuit

The feedback is in the operation of the differential pair itself. By feeding it with a current source itail, common signals don't cause changes in the drain currents.

 

[srimatresri]

i figure d it out.
@fvm:
the i-tail is introduced later . initially it was grounded, even with ground there is an inherent common mode feed forward in the circuit. what we are doing
is , extracting the common mode signal from the output. here the average current is prevented from going in to the load. so no common mode voltage is developed.

 

[FvM]

There's a bias current compensation in the output signal by substracting I1 and I2, but no feedback. You could rather designate it a feed forward.

 

[srimatresri]

u are right