Question

In a Common Emitter (CE) configuration, what is the phase shift between input and output?

• A. 0°
• B. 90°
• C. 180°
• D. 270°

Hint:

Common Emitter → Output is inverted → Phase shift = 180°.

Answer 1

The Correct Option is C

Concept: In transistor amplifier configurations, the phase relationship between input and output signals is an important characteristic.
Step 1: Understanding CE configuration.
In a Common Emitter configuration, the input is applied between base and emitter, and output is taken between collector and emitter.
Step 2: Phase relationship.
When the input signal increases, the collector current increases, causing a larger voltage drop across the collector resistor.
Step 3: Effect on output voltage.
This results in a decrease in output voltage, meaning the output signal is inverted relative to the input.
Step 4: Phase shift.
This inversion corresponds to a phase shift of: \[ 180^\circ \]
Step 5: Conclusion.
Thus, the CE amplifier produces a 180° phase shift.