GATE Electrical – Analog Electronics
Practice Problems – Page 1
This section contains conceptual and numerical problems based on PN Junction Diode and Basic Amplifier Concepts. Each question includes a clear explanation.
Problem 1
Question:
What is the typical cut-in voltage of a silicon diode?
Options:
- A) 0.2 V
- B) 0.3 V
- C) 0.7 V
- D) 1.5 V
Answer: C) 0.7 V
Explanation:
For silicon diodes, the cut-in voltage is approximately 0.7 V, while for germanium diodes it is about 0.3 V.
Problem 2
Question:
Which region of a diode is responsible for current conduction?
Answer: Depletion region reduces and carriers move across the junction.
Explanation:
When forward bias is applied, the depletion region narrows, allowing charge carriers to cross the junction.
Problem 3
Question:
What is the thermal voltage at room temperature?
Answer:
VT ≈ 25 mV
Explanation:
Thermal voltage is given by:
VT = kT/q
At room temperature it is approximately 25 mV.
Problem 4
Question:
A CE amplifier has:
- hfe = 100
- hie = 1 kΩ
- RL = 4 kΩ
Find voltage gain.
Solution:
Av = − (hfe × RL) / hie
Av = − (100 × 4000) / 1000
Av = − 400
Negative sign indicates 180° phase shift.
Problem 5
Question:
What is the main function of a rectifier?
Answer: Convert AC into DC.
Explanation:
Rectifiers allow current flow in only one direction, thereby converting alternating current into direct current.
Problem 6
Question:
Which amplifier configuration provides the highest voltage gain?
Answer: Common Emitter (CE)
Explanation:
The CE amplifier provides high voltage gain and moderate input/output impedance, making it the most widely used amplifier configuration.
Problem 7
Question:
What does CMRR stand for?
Answer: Common Mode Rejection Ratio
Explanation:
CMRR measures the ability of a differential amplifier to reject common mode signals.
Problem 8
Question:
Write the formula for differential amplifier gain.
Answer:
Ad = RC / (2re)
Problem 9
Question:
What is the ideal input impedance of an operational amplifier?
Answer: Infinite
Explanation:
An ideal op-amp draws no input current.
Problem 10
Question:
What is the ideal output impedance of an op-amp?
Answer: Zero
Explanation:
An ideal op-amp can deliver output voltage without internal voltage drop.
.png)
No comments:
Post a Comment