Question

For the circuit shown in Figure below:

R1 = 10KOmega, R2= 1MOmega,
R3 = 10KOmega, R4 = 10KOmega, R5 = 150KOmega, R6 = 10KOmega. Find Av=Vo/Vi

Answer 1

Av = -800

Step-by-step explanation:

The gain to the output of the first op-amp is ...

A1 = -R2/R1 = -1000/10 = -100

The gain of the voltage divider R3/R4 is ...

A2 = R4/(R3+R4) = 10/(10+10) = 1/2

The gain of the second op-amp circuit from the positive terminal to the output is ...

A3 = 1+ R5/R6 = 1 + 150/10 = 16

Then the total circuit gain is ...

Av = A1×A2×A3 = (-100)(1/2)(16)

Av = -800

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Additional comment

In the above, we have assumed ideal op-amps, with infinite gain and infinite input impedance. The resistor values used in the calculations are all Kohms, so we can avoid writing unnecessary zeros.