GATE Electrical Engineering - Complete Master Library

 

GATE Electrical – Analog Electronics

Practice Problems – Page 7

This section contains problems based on h-parameter model of transistor amplifiers.

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Problem 61

Question:

Write the four h-parameters of a transistor amplifier.

Answer:

• h_ie – Input impedance
• h_re – Reverse voltage gain
• h_fe – Forward current gain
• h_oe – Output admittance

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Problem 62

Question:

What does h_fe represent in transistor amplifier?

Answer:

Forward current gain in common emitter configuration.

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Problem 63

Question:

If h_fe = 120 and base current = 30 μA, find collector current.

Solution:

Ic = hfe × Ib

Ic = 120 × 30 μA

Ic = 3600 μA = 3.6 mA

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Problem 64

Question:

Which h-parameter represents output conductance?

Answer:

h_oe

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Problem 65

Question:

What is the approximate voltage gain of CE amplifier using h-parameters?

Formula:

Av ≈ − hfe × RL / hie

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Problem 66

Question:

If h_fe = 100, R_L = 2 kΩ and h_ie = 1 kΩ, find voltage gain.

Solution:

Av = − (100 × 2000) / 1000

Av = −200

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Problem 67

Question:

If h_ie increases, what happens to input impedance?

Answer:

Input impedance increases.

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Problem 68

Question:

Why is h_re usually neglected in amplifier analysis?

Answer:

Because its value is extremely small.

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Problem 69

Question:

Which parameter mainly controls current amplification?

Answer:

h_fe

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Problem 70

Question:

What is the main advantage of h-parameter model?

Answer:

It simplifies transistor amplifier analysis using linear equations.