Op-Amp Lab Activity: Inverting vs. Non-Inverting Configurations

📋 Overview

🔴 Inverting

🔵 Non-Inverting

📊 Results

🧠 Analysis

Lab Activity Overview

Estimated time: 60–90 minutes | Individual or paired activity

🎯 Learning Objectives

Explain the difference between inverting and non-inverting operational amplifier configurations.
Calculate voltage gain using the appropriate formula for each configuration.
Predict output voltage based on input voltage and resistor values.
Interpret waveform phase relationships between input and output signals.
Synthesize findings into a comparative analysis of both configurations.

Background

The operational amplifier (op-amp) is one of the most versatile building blocks in analog electronics. Depending on how feedback resistors are connected, the same op-amp IC can amplify a signal while preserving its phase (non-inverting) or flip the output 180° out of phase with the input (inverting). Understanding both configurations is essential for designing analog circuits in audio, instrumentation, and control systems.

Lab Procedure

Step 1 — Inverting Op-Amp Simulator (Tab 2)

Use the interactive simulator to explore the inverting configuration. Adjust the input voltage (Vin), feedback resistor (Rf), and input resistor (Rin). Record at least four data points in the Results table. Observe the waveform and note the phase relationship.

Step 2 — Non-Inverting Op-Amp Simulator (Tab 3)

Switch to the non-inverting simulator. Adjust Vin, Rf, and Rg. Record at least four data points. Note the minimum gain of 1 and observe that the output remains in phase with the input.

Step 3 — Results Table (Tab 4)

Enter your collected data into the structured results table. Verify your hand-calculated gain values match the simulator output. Complete the comparison summary.

Step 4 — Analysis Questions (Tab 5)

Answer all six analysis questions using your data and observations. Submit your completed lab to your instructor for AI-enhanced feedback review.

Grading Rubric

Criterion

Points

Performance Indicators

Simulator Exploration & Data Collection

4+ data points for each configuration; Vin, Rf, Rin/Rg, calculated gain, Vout all recorded accurately.

Gain Formula Application

Correct formula used for each type; hand-calculated values match simulator within ±5%.

Phase Relationship Identification

Correctly identifies 180° phase inversion for inverting; in-phase relationship for non-inverting.

Comparative Analysis

Analysis questions answered with specific references to data; demonstrates conceptual synthesis beyond simple description.

Application Scenario

Correctly identifies a real-world application for each configuration with engineering justification.

Total

100

🔴 Inverting Op-Amp Configuration

In this configuration, the input signal is applied through Rin to the inverting (−) terminal. The output is 180° out of phase with the input. Gain is always negative.

Av = −(Rf / Rin) | Vout = Av × Vin

⚡ Inverting Op-Amp Simulator

Vin (Input Voltage) 1.0 V

Rf (Feedback Resistor) 10 kΩ

Rin (Input Resistor) 10 kΩ

Voltage Gain (Av)

−1.00

Vout

−1.00 V

Recorded Data Points

#	Vin (V)	Rf (kΩ)	Rin (kΩ)	Av (calc)	Vout (V)	Phase
No data recorded yet. Adjust sliders and click Record.

💡 Key Observations to Note

What happens to the output polarity when Vin is positive? Negative?
When Rf = Rin, what is the gain? What does this tell you about unity gain?
How does doubling Rf while keeping Rin constant affect the output voltage?
Observe the waveform — the output is 180° shifted from the input.

🔵 Non-Inverting Op-Amp Configuration

The input signal is applied directly to the non-inverting (+) terminal. Output is in phase with the input. Gain is always ≥ 1 (positive).

Av = 1 + (Rf / Rg) | Vout = Av × Vin

⚡ Non-Inverting Op-Amp Simulator

Vin (Input Voltage) 1.0 V

Rf (Feedback Resistor) 10 kΩ

Rg (Ground Resistor) 10 kΩ

Voltage Gain (Av)

+2.00

Vout

+2.00 V

Recorded Data Points

#	Vin (V)	Rf (kΩ)	Rg (kΩ)	Av (calc)	Vout (V)	Phase
No data recorded yet. Adjust sliders and click Record.

💡 Key Observations to Note

What is the minimum possible gain for a non-inverting amplifier, and why?
How does the phase of the output compare to the input in every trial?
When Rf = 0 (or Rg is very large), what configuration does this approach?
Compare the gain formula here to the inverting: what is structurally different?

📊 Results & Data Summary

Enter your final recorded data below. Ensure at least 4 trials for each configuration. Verify your hand-calculated values against the simulator outputs.

Inverting Op-Amp — Final Data Table

Trial	Vin (V)	Rf (kΩ)	Rin (kΩ)	Av Formula = −Rf/Rin	Vout = Av × Vin	Phase Shift
1
2
3
4

Non-Inverting Op-Amp — Final Data Table

Trial	Vin (V)	Rf (kΩ)	Rg (kΩ)	Av Formula = 1+Rf/Rg	Vout = Av × Vin	Phase Shift
1
2
3
4

Configuration Comparison Summary

Parameter	Inverting	Non-Inverting
Gain Formula	Av = −Rf/Rin	Av = 1 + Rf/Rg
Minimum Gain	No lower limit (neg.)	Always ≥ 1
Phase Shift	180°	0° (in-phase)
Input Impedance	Equal to Rin	Very High (≈ ∞)
Input Terminal Used	Inverting (−)	Non-Inverting (+)
Unity Gain Possible?
Real-World Application

Lab Completion Progress20%

🧠 Analysis & Synthesis

Answer all six questions thoughtfully using your collected data. Reference specific trial numbers and values where possible. Demonstrate conceptual understanding, not just data recitation.

Student Name: Date:

Question 1 — Gain Formula Comparison

Compare the gain formulas for the inverting and non-inverting op-amp configurations. Explain why the inverting configuration produces a negative gain value, and what this means physically for the output signal.

0 / 50 words minimum

Question 2 — Phase Relationship

Describe the phase relationship between input and output for each configuration. Use your waveform observations to support your explanation. Why does the phase inversion occur in the inverting configuration?

0 / 50 words minimum

Question 3 — Minimum Gain Analysis

Explain why the minimum gain of the non-inverting op-amp is always 1 (or greater). What resistor values would achieve a gain of exactly 1, and what is this special configuration called?

0 / 40 words minimum

Question 4 — Input Impedance

The non-inverting configuration has significantly higher input impedance than the inverting configuration. Explain why this is the case based on where the input signal is applied. Describe one practical scenario where this difference would matter to a circuit designer.

0 / 50 words minimum

Question 5 — Real-World Application Selection

You are designing a signal conditioning circuit for a microphone that feeds into an audio amplifier. The microphone has a very high output impedance. Which op-amp configuration would you choose and why? Would you need phase inversion to be a concern?

0 / 60 words minimum

Question 6 — Synthesis & Critical Thinking

Based on all of your data and observations, write a concise technical summary (3–5 sentences) that a junior technician could use to decide which op-amp configuration to use for a given design task. Include gain behavior, phase, and impedance considerations.

0 / 75 words minimum

🤖 AI-Enhanced Feedback — Instructor Tool

When students submit this lab, instructors can paste the student's responses into the AI prompt below to generate targeted, rubric-aligned feedback. The AI is provided the lesson objectives and grading criteria to ensure feedback is specific, formative, and exam-focused.

✅ Ready to Submit?

Ensure all six analysis questions are answered and your data tables in Tab 4 are complete. Click the button below to generate a printable summary of your responses.