Tuesday, 10 March 2026

Operational Amplifiers – Complete Theory

Page 8 – Differential Amplifier (Subtractor)

Picture used in analog electronics

The Differential Amplifier is an operational amplifier circuit that amplifies the difference between two input signals.

It is also called a Subtractor Circuit.

Purpose of Differential Amplifier

Amplifies the difference between two voltages
Rejects common noise signals
Used in instrumentation and sensor circuits

Circuit Components

Four resistors (R1, R2, R3, R4)
Two input voltages (V1 and V2)
One operational amplifier

Voltage at Non-Inverting Terminal

Using voltage divider:

V+ = (R4 / (R3 + R4)) × V2

Voltage at Inverting Terminal

Using op-amp property:

V− ≈ V+

Output Voltage Derivation

The general output equation is:

Vout = (R2 / R1) (V2 − V1)

Special Case (Balanced Differential Amplifier)

If

R1 = R3 R2 = R4

Then

Vout = (R2/R1) (V2 − V1)

Applications

Instrumentation amplifiers
Noise rejection circuits
Sensor signal conditioning
Data acquisition systems

GATE Important Points

Amplifies difference between two inputs
Rejects common-mode signals
Used in instrumentation amplifiers
Important concept: Common Mode Rejection Ratio (CMRR)

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)