Question about voltage difference in BJT differential amp

[Taskuraha]

Diff amp

So i want to assure one thing about diff amps. If we have ordinary bjt diff amp. Does voltage difference between two base occur only ac-signal difference. So dc/bias voltage is same both transistors base, because bias current is I/2 for both transistor

 

[krashkealoha]

Re: Diff amp

An applied voltage difference on the base can be either AC or DC. Usually, if the input voltage difference is less than 3VT (~78mVpp) the diffamp stage is operating in the linear range. Input voltages greater than 3VT will fully switch one side of the diff pair, where >90% of the tail current will flow through the transistors, whose base is at the higher potential.

 

[khafaji]

Diff amp

Yes it is beeter that use the same DC bias for good result. also you can use different bias points but this not recommended