Syllabus

🔹 Unit I – Bipolar Junction Transistor (BJT)

Hours: 8 | Marks: 8

1) Types of Transistors

Two types:

• NPN Transistor

• PNP Transistor

2) Construction of Transistor

Three regions:

• Emitter (E)

• Base (B)

• Collector (C)

Emitter → heavily doped
Base → thin and lightly doped
Collector → moderately doped

3) Working of Transistor

NPN Transistor:

Current flows:

Collector → Emitter

PNP Transistor:

Current flows:

Emitter → Collector

4) Transistor Configurations

Three modes:

• CB – Common Base

• CE – Common Emitter

• CC – Common Collector

CE is most widely used amplifier.

5) Current Gain

Alpha (α):

$$\alpha = \frac{I_C}{I_E}$$

Beta (β):

$$\beta = \frac{I_C}{I_B}$$

Relation:

$$\beta = \frac{\alpha}{1-\alpha}$$

6) DC Load Line

Graph between:

Collector current and voltage

7) Operating Regions

Active Region → Amplifier region

Cut-off Region → OFF

Saturation Region → ON

🔹 Unit II – Transistor Biasing and Operational Amplifier

Hours: 7 | Marks: 7

Transistor Biasing

Purpose:

Maintain stable operation

1) Stability Factor

Maintains Q-point stability

2) Thermal Runaway

Temperature ↑ → Current ↑ → Damage

3) Base Bias

Simple bias circuit

4) Emitter Bias

More stable bias

Operational Amplifier (OP-AMP)

Block Diagram

Stages:

• Input stage

• Amplifier stage

• Output stage

Ideal OP-AMP Characteristics

• Infinite gain

• Infinite input resistance

• Zero output resistance

IC 741 Pin Diagram

Most commonly used OP-AMP

Parameters

• Input bias current

• Input offset current

• Offset voltage

• Slew rate

• CMRR

Virtual Ground

Voltage at inverting terminal = 0

Applications

Inverting Amplifier

Negative output

Non-Inverting Amplifier

Positive output

Adder

Adds signals

Subtractor

Subtract signals

🔹 Unit III – Fiber Optics

Hours: 7 | Marks: 7

Definition

Fiber optics is transmission of light through fiber

Principle:

Total Internal Reflection

Structure of Optical Fiber

Parts:

• Core

• Cladding

• Jacket

Classification

Types:

• Single mode

• Multimode

Propagation of Light

Light travels by reflection

Acceptance Angle

Maximum angle of entry

Numerical Aperture

Formula:

$$NA = \sqrt{n_1^2 - n_2^2}$$

Fiber Optic Communication

Used in internet communication

Advantages

• High speed

• Less loss

Disadvantages

• Expensive

Applications

• Internet

• Medical

• Communication

🔹 Unit IV – Laser

Hours: 8 | Marks: 8

LASER Full Form:

Light Amplification by Stimulated Emission of Radiation

Characteristics

• Monochromatic

• Coherent

• Directional

Types of Emission

Absorption

Spontaneous emission

Stimulated emission

Population Inversion

More atoms in excited state

Pumping

Energy supply

Laser Components

• Active medium

• Pumping source

• Resonator

Laser Types

Ruby Laser

Solid state laser

He-Ne Laser

Gas laser

Applications

Medical

Eye surgery

Industrial

Cutting

Agriculture

Land leveling

Research

Scientific research

1. Explain the construction, working, and configurations of PNP and NPN transistors, and interpret their characteristics in CB and CE modes.

2. Analyze transistor biasing circuits, stability factors, and the DC load line to determine the operating point in different regions (active, cut-off, saturation).

3. Evaluate the performance of CE amplifiers by calculating input/output impedance, current gain, voltage gain, and power gain using hybrid parameters.

4. Describe the principles of fiber optics, including total internal reflection, light propagation, and the significance of acceptance angle and numerical aperture.

5. Compare the advantages and disadvantages of optical fibers and their applications in communication systems.

6. Illustrate the working of lasers, including population inversion and pumping processes in three-level and four-level systems.

7. Discuss the applications of Ruby and He-Ne lasers in medical, industrial, agricultural, and research fields.

8. Solve numerical problems related to transistor biasing, fiber optics, and laser parameters.