First unit of Analog and Digital Electronics of DBATU Lonere

1. Analog and Digital Electronics
Prof. P. V. Gaikwad

2. Syllabus Structure

3. Syllabus

5. Unit I
Transistor as an amplifier

6. Basics of Transistor
What is a Transistor?
 A transistor is an electronic component that is used in circuits to
either amplify or switch electrical signals or power, allowing it to be
used in a wide array of electronic devices.
 A transistor consists of two PN diodes connected back to back.
 It has three terminals namely emitter, base and collector.
 The basic idea behind a transistor is that it lets you control the flow
of current through one channel by varying the intensity of a much
smaller current that’s flowing through a second channel.

7. Different Types of Transistors

8. Types of BJT

9. Working of BJT

10. Operating Regions of BJT

11. Working Principle of BJT
• The emitter-base junction of BJT is forward-
biased, whereas the collector-base junction is
reverse biased.
• The forward bias of the emitter-base junction
causes the emitter current to flow and this
emitter current entirely flows in the collector
circuit.
• Therefore, the collector current depends upon
the emitter current and nearly equal to the
emitter current.

12. Working of NPN Transistor

13. Working of PNP Transistor

14. Different configurations of BJT
• Common Base Configuration
• Common Emitter Configuration
• Common Collector Configuration

15. Common-Base Configuration
• In this type of configuration, the base terminal of the transistor serves as a common terminal,
so it is called as common-base (CB) configuration.
• The input voltage is applied between base and emitter terminal. The output is taken between
collector and base terminal of the device.
• Common-base configuration has low input resistance but a high output resistance.
• Current gain in common-base configuration is denoted by Greek letter α (alpha).
• It is defined as the ratio of collector current to the emitter current.

16. Common Emitter Configuration
• This type of configuration is called as common-emitter (CE) configuration as the emitter
terminal of the transistor is made as a common terminal.
• The input voltage is applied between base and emitter terminal of the transistor.
• The output is obtained between emitter and collector terminal.
• Common-emitter configuration has a low input resistance but very high output resistance.
• Current gain in common-emitter configuration is denoted by a Greek letter ß (beta).
• It is defined as the ratio of collector current to the base current.

17. Common Collector Configuration
• This type of configuration is called as common-collector (CC) configuration as the collector
terminal of the transistor is made as a common terminal.
• The input voltage is applied between base and collector terminal of the transistor.
• The output is obtained between emitter and collector terminal of the transistor.
• Common-collector terminal has a very high input resistance but a low output resistance.
• Current gain in common-collector configuration is denoted by Greek letter γ (gamma).
• It is defined as the ratio of emitter current to the base current.

18. Input and output characteristics of CB
configuration

19. Input and output characteristics of CC
configuration

20. Input and output characteristics of CE
configuration

21. Load Line