differential amplifier question
hi,
I am making a differntial amplifier, and the circuit i am trying is attached as a Pdf. In my simulations when i probe the voltage at the collector of Q1 and Q3 i see they are in phase. If i remove the second stage (AD797) they are fine in quadrature with each other.
I am not sure, what is causing this? Is it correct at all,? The AD797 which is supposed to get rid of common mode signal and amplify the differential signal won't help in this case.
some explaination wld help. thanks