I was trying to find the difference between implementing a differential and a double input differential amplifier for a comparator, advantages and disadvantages, I couldnt find anything about...
I am implementing a double differential two stage OPAMP with single output, with two of the inputs referred to same reference CC and the other two inputs will be compared. I know that is not necessary, but I wonder if there is some advantage on that design.
In my opinion, the unique advantage for calling it so, is that, at the first stage, the output transistors have always current flowing through them, they are always in saturation, but I dont exactly know if it is an advantage.
Someone could help me? Thank you!

 

Saturated transistor in an amplifier = you clip the output = bad;
Draw the schematic and post it. But first, you will want to take a look at this http://www.allaboutcircuits.com/vol_3/chpt_4/1.html and this http://www.allaboutcircuits.com/vol_3/chpt_8/1.html

 

Vbandgap is 1.2V, Vref and Vemitter are the signals to be compared, they vary around 400mV to 800mV