I'm not trying to make a better/different diff pair, I'm just wondering how people would calculate that setup.
Ok so it is just a planer circuit, and if I set some tail current and assume both BJT's are the same and in the linear region, I can calculate V1. Then with a few guesses of the base current splits, and the BJT diode eqn, I can get a pretty close value, such that VBE1=VBE2+R3*Ibase2
For instance with fixed Ie=3.8mA, (Ib1+Ib2)=Ie/301=12.62uA, if Ibase1=8uA, then 719.6mV=705.4mV + 3300*4.63uA=720.6mV, pretty close
That's with Beta=300 and Is=1.96fA
What's a better way than trial/error to solve something like VBE1=VBE2+R3*Ibase2 ?