Math Problem Statement

Given the input voltages v1 and v2 in the op-amp amplifier circuit with resistors, find the expression for the output voltage Vo in terms of v1 and v2. The input voltages are given as v1 = 10 sin(120πt) + 0.25 sin(5000πt) and v2 = 10 sin(120πt) - 0.25 sin(5000πt).

Solution

In the given image, we have an op-amp circuit with input voltages v1v_1 and v2v_2, and the task is to find the expression for the output voltage vov_o based on these inputs. The problem asks for an expression for vov_o in terms of v1v_1 and v2v_2, assuming the operational amplifier is ideal.

Step-by-step analysis:

  • The op-amp configuration is a differential amplifier, which takes the difference between v1v_1 and v2v_2 and amplifies it by a factor set by the resistances.
  • The formula for the output voltage of a differential amplifier is: vo=(RfR1)v1(RfR2)v2v_o = \left( \frac{R_f}{R_1} \right) v_1 - \left( \frac{R_f}{R_2} \right) v_2 where:
    • RfR_f is the feedback resistor (101 kΩ\Omega),
    • R1R_1 is the resistor connected to v1v_1 (9.9 kΩ\Omega),
    • R2R_2 is the resistor connected to v2v_2 (10.1 kΩ\Omega).

Applying the values:

  • From the circuit: vo=(101kΩ9.9kΩ)v1(101kΩ10.1kΩ)v2v_o = \left( \frac{101 \, \text{k}\Omega}{9.9 \, \text{k}\Omega} \right) v_1 - \left( \frac{101 \, \text{k}\Omega}{10.1 \, \text{k}\Omega} \right) v_2

  • Simplifying the ratios: 1019.910.202,10110.110.000\frac{101}{9.9} \approx 10.202, \quad \frac{101}{10.1} \approx 10.000

Thus, the output voltage expression becomes: vo=10.202v110.000v2v_o = 10.202 v_1 - 10.000 v_2

This is the desired expression for the output voltage vov_o in terms of v1v_1 and v2v_2.

Would you like me to go into more details or clarify anything? Here are some related questions:

  1. How do ideal op-amp assumptions affect the analysis?
  2. What happens if we change the feedback resistor value RfR_f?
  3. Can we express vov_o differently if we use different resistor ratios?
  4. How does the input frequency content of v1v_1 and v2v_2 affect the output?
  5. What are the conditions for stability in such an op-amp circuit?

Tip: Always double-check resistor values in differential amplifier circuits, as small differences can significantly affect the output gain.

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Math Problem Analysis

Mathematical Concepts

Electrical Circuit Analysis
Op-Amp Theory
Differential Amplifiers

Formulas

Vo = (Rf/R1) * v1 - (Rf/R2) * v2
Rf = 101 kΩ, R1 = 9.9 kΩ, R2 = 10.1 kΩ

Theorems

Ideal Op-Amp Assumptions
Differential Amplifier Output Equation

Suitable Grade Level

University (Electrical Engineering)