The operational amplifier, commonly called an op-amp,
is one of the most widely used analog electronic building blocks.
It can perform amplification, filtering, mathematical operations,
signal conditioning and many other functions.
π― Experiment Objectives
Understand the basic operation of an operational amplifier.
Understand the inverting amplifier configuration.
Understand the non-inverting amplifier configuration.
Investigate voltage gain.
Observe the phase relationship between input and output.
Understand the effect of resistor values on gain.
Observe output saturation when the signal exceeds the supply limits.
π¨βπ Think Before You Start
Why does an op-amp need a power supply?
Why does the inverting amplifier produce phase inversion?
What determines the voltage gain?
What happens if the calculated output exceeds the supply voltage?
π 1. Theory
Operational Amplifier
An operational amplifier is a high-gain differential amplifier.
It has two input terminals and one output terminal.
The inputs are conventionally called the inverting input
and non-inverting input.
Ideal Op-Amp Assumptions
Very high open-loop voltage gain.
Very high input impedance.
Very low output impedance.
Input current is approximately zero.
Inverting Amplifier
Av = β Rf / Rin
The negative sign indicates that the output is approximately
180Β° out of phase with the input.
Non-Inverting Amplifier
Av = 1 + Rf / Rg
The non-inverting amplifier produces an output that is
in phase with the input signal.
Output Limitation
A practical op-amp cannot produce an output voltage greater
than its available supply rails. In this virtual experiment,
the output is therefore limited to the selected supply range.
Purple = input signal.
Blue = amplified output signal.
π 6. Voltage Transfer Characteristic
π¬ 7. Engineering Analysis
π 8. Student Observation Table
Trial
Configuration
Vin
Gain
Ideal Vout
Actual Vout
Phase
π 9. Experiment Conclusion
The operational amplifier can be configured as an inverting
or non-inverting voltage amplifier.
For the inverting amplifier, the voltage gain is determined
by the ratio of the feedback resistance to the input resistance,
and the output is phase inverted.
For the non-inverting amplifier, the output remains in phase
with the input and the voltage gain is determined by the
feedback network.
The experiment also demonstrates that the actual output
cannot exceed the available supply voltage.
β 10. Student Quiz
Q1. An operational amplifier has how many input terminals?
Q2. The gain of an ideal inverting amplifier is:
Q3. The output of an inverting amplifier is approximately:
Q4. The gain of a non-inverting amplifier is:
Q5. What happens when the required output exceeds the supply rail?
π€ CHITTI
GARRF Robotics & Engineering AI Mentor
Students can use CHITTI to explore the concepts behind this
experiment and ask engineering questions.
π‘ Try asking:
"What is an operational amplifier?"
"Explain an inverting amplifier."
"Why is the output phase inverted?"
"How do I calculate op-amp gain?"
"What is saturation?"
π¨βπ 11. How to Perform Experiment 12
Select Inverting Amplifier.
Set Rin and Rf.
Apply a small input voltage.
Observe the calculated voltage gain.
Observe the output voltage.
Increase the input voltage gradually.
Observe what happens when the output approaches the supply rail.
Record the measurements in the observation table.
Repeat the experiment using the non-inverting configuration.
Compare the gain and phase of the two configurations.
β Engineering Challenge
Design a virtual amplifier with a voltage gain of approximately
10 without causing output saturation. Try different resistor
combinations and input voltages.
β οΈ Real Laboratory Safety
Important:
This is a virtual experiment. In a physical laboratory,
always verify power-supply polarity, resistor values and
op-amp pin configuration before energizing a circuit.
Never connect laboratory circuits directly to mains voltage.
