We have to find the overall voltage gain of this circuit i.e Ad=V0/(V1-V3).
I have found the collector currents through each resistor except for transistors Q7 and Q8.
Also I have found the voltage gain for the first stage(consisting of Q1,Q2,Q3 and Q4) and the second stage (Q5 and Q6).
Now I know that to find the total voltage gain , I have to multiply the voltage gain of each stage taking in account the input resistance of the next stage .
But how do I find the voltage gain and input resistance of the third stage (Q7 and Q8).
I have found the collector currents through each resistor except for transistors Q7 and Q8.
Also I have found the voltage gain for the first stage(consisting of Q1,Q2,Q3 and Q4) and the second stage (Q5 and Q6).
Now I know that to find the total voltage gain , I have to multiply the voltage gain of each stage taking in account the input resistance of the next stage .
But how do I find the voltage gain and input resistance of the third stage (Q7 and Q8).