1. Thought of the Day excellence Commit yourself to
in every part of your life,
and never stop striving toward it.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

2. Electronic Amplifiers
D.C. Kulshreshtha
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

3. Electronic Amplifiers
What is amplification ?
Making things bigger or enlarged.
You are familiar with some non-electronic amplifiers.
Examples are Lever and Pulley System.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

4. Electronic Amplifiers
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

5. Electronic Amplifiers
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

6. Electronic Amplifiers
Both amplify force.
But, these are working movement reducer or attenuator.
Both are passive systems.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

7. Electronic Amplifiers
How is an electronic amplifier different from a step-up transformer ?
Ans. one is active system, the other is passive electrical system.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

8. Electronic Amplifiers
General Symbol
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

9. Electronic Amplifiers
BJT Amplifier
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

10. Electronic Amplifiers
The Capacitors
Two functions :
Coupling or Blocking Capacitors.
Bypass Capacitors.
A capacitor is dc open and ac short.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

11. Electronic Amplifiers
Analysis of Amplifier
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

12. Electronic Amplifiers
We can then obtain the total current (or voltage) in any branch by simply adding the dc current (or voltage) to the ac current (or voltage).
Often it is not needed.
The dc analysis is meant only to ensure that the Q-point is suitably fixed.
The exact value of Q-point does not matter.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

13. A Practical CE Amplifier
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

14. Electronic Amplifiers
DC Analysis
The Q-point is quite in the middle.
You don’t need these results any further.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

15. Electronic Amplifiers
AC Analysis
Two steps :
Reduce dc source to zero.
Short all capacitors.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

16. Electronic Amplifiers
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

17. Electronic Amplifiers
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

18. Electronic Amplifiers
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

19. Electronic Amplifiers
Is this circuit not so simple ? It has only three resistors and no capacitor at all.
Are we now ready for ac analysis ?
No. There are two alternatives.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

20. Electronic Amplifiers
1. Graphical Method
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

21. Electronic Amplifiers
Input signal voltage of 1 mV (peak-to-peak) is not enough for graphical analysis.
So, we can take 10 mV (peak-to-peak) signal.
To find amplifier gain, we consider the loss of signal due to the source resistance of 600 Ω.
We find that
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers

22. Electronic Amplifiers
Review
What is amplification ?
General Symbol.
BJT Amplifier.
The Capacitors.
Analysis of Amplifier.
A Practical CE Amplifier.
DC Analysis.
AC Analysis.
Graphical Analysis.
शुक्रवार, 18 जनवरी 2019
Electronic Amplifiers