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op-amp circuit

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Question:

Shree_vani

Oracle

Karma Points: 9,385

Date Posted: 7/15/2008 1:32:13 PM Status: Live

Asker's Rating: Helpful

Response:

Due to virtual short, the voltage at the inverting input of the first opamp is V₁

Due to virtual short, the voltage at the inverting input of the second opamp is V₁ / 2

The output of the opamp circuit 1 is connected to the input, that it it behaves as a voltage follower,

and its output is V₁

Simillary, the output of the opamp circuit 2 is connected to its input, that it it behaves as a voltage follower, and its output is V₁/2

Applying KCL at the inverting input of the opamp 3

I3 = I4

V₁ - V_x = V_x - V_o

2V_x = V_o + V₁ ----------------- (1)

Applying KCL at the noninvertin input of the opamp 3

I1 = I2

V₁ - 2V_x = V_x - V_o

V₁ - 3V_x = - V_o ------------- (2)

Form (1) and (2)

V₁ - 3(V_o + V₁ )/2 = - V_o

2V₁ - 3V_o - 3V₁ = -2V_o

-V₁ = V_o

V_o = -V₁

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