Calculating Voltage Gain Vo/Vi of an Op-Amp Circuit

In summary, the conversation discusses how to determine the voltage gain of an op-amp circuit using the equations for an inverting amplifier and a differential amplifier. The conversation also includes a suggestion to redraw the circuit for better understanding and clarification on the values of R1 and R2. After calculations, the voltage gain is found to be 122.233.
  • #1
gazp1988
32
0

Homework Statement


Determine the voltage gain Vo/Vi of the op-amp circuit
upload_2016-3-20_21-57-54.png

Homework Equations


inverting amplifer
vout=-(Rf/Rin) x vin

differential amplifer
vout= (R2/R1) x (vo - vin)

The Attempt at a Solution


im really struggling to even get started with this one sorry for the limited information i just need a starting block.
 

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  • #2
The file you attached is not applicable to the circuit in your post. Notice that in the attached file there is a path from output to the "+" input of the same opamp. That configuration is not in your posted circuit.

Try redrawing your circuit by moving the lower opamp upward and to the left of the upper opamp, and make it face in the same direction. That should help in seeing the overall function. If you're still having trouble, start by considering the two opamp circuits individually.

gazp1988 said:
differential amplifer
vout= (R2/R1) x (vo - vin)

Where/what are R2, R1?
 
  • #3
sorry about the attached file i don't know why it did that, it has nothing to do with my circuit.o_O

this is what i have so far.

inverting amplifier

vout= -(RF/RIN) X VIN
Vout = -(68/12) x Vin
Vout = -5.667Vin

Differential amplifier
vout = -(R2/R1) x (VX x VIN)
Vout = -(220/12) x (VX x VIN)
Vout = -18.334 x ((-5.667Vin) - Vin)
Vout = -18.334 x (-6.667Vin)
vo/vi = 122.233
 
  • #4
VX and VIN are Multipied here...
gazp1988 said:
Vout = -(220/12) x (VX x VIN)
...but Added here.
gazp1988 said:
Vout = -18.334 x ((-5.667Vin) - Vin)
WHY?

R1 & R2 are still undefined.
 
  • #5
Where/what are R2, R1?[/QUOTE]

R2 in the formula is the feedback resistor, R1 the series one.
 
  • #6
gazp1988 said:
sorry about the attached file i don't know why it did that, it has nothing to do with my circuit.o_O

this is what i have so far.
vo/vi = 122.233

This result is correct.
 

1. What is an op-amp circuit?

An op-amp (operational amplifier) circuit is a type of electronic circuit that uses an amplifier to amplify the difference between two input voltages. It is commonly used in electronics and can perform a variety of functions such as amplification, filtering, and signal conditioning.

2. How is voltage gain calculated in an op-amp circuit?

Voltage gain (Vo/Vi) in an op-amp circuit is calculated by dividing the output voltage (Vo) by the input voltage (Vi). It is typically expressed in decibels (dB) and can be calculated using the formula: Voltage Gain (dB) = 20 x log (Vo/Vi).

3. What factors affect the voltage gain in an op-amp circuit?

The voltage gain in an op-amp circuit can be affected by various factors such as the op-amp's open-loop gain, input and output resistances, and feedback components. Changes in these factors can result in changes in the overall voltage gain of the circuit.

4. How can the voltage gain of an op-amp circuit be adjusted?

The voltage gain of an op-amp circuit can be adjusted by changing the values of the feedback components, such as resistors and capacitors. These components can be added or removed from the circuit to increase or decrease the gain as needed.

5. Can the voltage gain of an op-amp circuit be greater than 1?

Yes, the voltage gain of an op-amp circuit can be greater than 1. In fact, op-amps are designed to have high voltage gain, typically in the range of thousands to millions. This allows them to amplify very small input signals to a larger output signal.

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