1. U20ECT303 - ANALOG ELECTRONIC CIRCUITS

2. Course Objectives
To analyze transistor biasing circuits and its stabilization techniques
To analyze the amplifier using h-parameters and low frequency FET model.
To familiarize the theory of multistage and feedback amplifiers
To understand the fundamentals of feedback amplifiers and concepts of oscillators
To understand the concepts of Large Signal Amplifiers

3. Course Outcomes
After completion of the course, the students are able to
CO1 – Design the biasing circuits (K2)
CO2 - Design and analyze the BJT and FET Amplifiers in both low and high
frequency (K3)
CO3 - Illustrate the design and analyze multistage and feedback amplifiers (K3)
CO4 - Construct and analyze oscillators and multivibrators. (K3)
CO5- Differentiate the power amplifiers based on their operation, efficiency and distortion (K3)

4. UNIT– I BIASING and Stabilization
Biasing and Stabilization: DC load line and Q-point – Need for biasing – Different types of BJT biasing – Fixed bias, Collector to base bias, Self-bias –Stability factor – Bias compensation: Diode, Thermistor and Sensistor compensation – FET biasing: Gate bias, Voltage divider bias and Self bias – MOSFET biasing.
UNIT– II LOW AND HIGH FREQUENCY ANALYSIS Transistor Low Frequency Analysis: Definition of h–parameters – Small signal low frequency h-parameter model –Mid band analysis of CB, CE and CC amplifier to obtain gain, input impedance and output impedance – Analysis of CE amplifier with an emitter resistance – Low frequency FET model – CS, CD and CG amplifiers.
Transistor High Frequency Analysis: Hybrid pi CE transistor model – Hybrid pi conductance and capacitances – CE short circuit current gain using Hybrid pi model - Current gain with resistive load.

5. UNIT– III AMPLIFIERS
Multistage Amplifiers: Need for cascading – Cascade amplifier – Cascode amplifier – Darlington Pair – Basic emitter coupled differential amplifier – Tuned amplifiers – single tuned –double tuned –stagger tuned amplifiers.
Feedback Amplifiers: Concept of feedback- topological classification-voltage series, voltage shunt, current series, current shunt - effect of feedback on gain, stability, distortion, band width, input and output impedances – practical feedback amplifier circuits and their analysis.

6. UNIT– IV OSCILLATORS AND MULTIVIBRATORS
UNIT– IV OSCILLATORS AND MULTIVIBRATORS Oscillators: Barkhausen criterion for sustained oscillations - RC oscillators – RC phase shift oscillator and Wien bridge oscillator- LC oscillators - Hartley and Colpitts oscillators – crystal oscillators and frequency stability.
Multivibrators: Astable, monostable and bistable multivibrators using transistors–Schmitt trigger circuit. Time Base Generators: General features of time base signals – RC ramp generator –Constant current ramp generator, UJT saw tooth generator – Bootstrap ramp generator
UNIT– V LARGE SIGNAL AMPLIFIERS
Classification of power amplifiers Class A power amplifier-direct and transformer coupled amplifiers; -Class B - Push-pull arrangements and complementary symmetry amplifiers; conversion efficiency calculations, cross over distortion – class AB amplifier - amplifier distortion – power transistor heat sinking – Class C and D amplifiers.

7. Text Books:
David A. Bell, “Electronic Devices and Circuits”, Oxford University Press, 5th edition, 2008
Adel.S.Sedra, Kenneth C.Smith, Microelectronic Circuits Theory and Applications, 7th Edition, Oxford University, 2017
Millman J and Halkias C, “Integrated Electronics”, Tata McGraw Hill International Edition, 2007. 
  Reference Books:
R.L. Boylestad and L. Nashelsky, “Electronic Devices and Circuit Theory”, PHI Learning Pvt. Ltd, India, Ninth Edition, 2008
S. Salivahanan, N.SureshKumar and A. Vallavaraj, “Electronic Devices and Circuits”, 2nd Edition, TMH, 2007.
Thomas L.Floyd, Fundamentals of Analog Circuits, Pearson Publication, 2nd Edition,2012
Jacob Millman, Arvin Grabel, “Microelectronics”, 2nd edition, Tata McGraw Hill, New Delhi. 2003
Neamen, Donald A., “Electronic Circuit Analysis and Design”, 3rd edition, McGraw Hill, 2006

15. Load line and Q Point
When a line is drawn joining the saturation and cut off points, such a line can be called as Load line.
This line, when drawn over the output characteristic curve, makes contact at a point called as Operating point. This operating point is also called as quiescent point or simply Q-point.

16. Faithful Amplification
The operating point should not get disturbed as it should remain stable to achieve faithful amplification. Hence the quiescent point or Q-point is the value where the Faithful Amplification is achieved.
Faithful Amplification
The process of increasing the signal strength is called as Amplification. This amplification when done without any loss in the components of the signal, is called as Faithful amplification.
Faithful amplification is the process of obtaining complete portions of input signal by increasing the signal strength. This is done when AC signal is applied at its input.

17. Operating Point

18. Operating Point Continued
In the above graph, the input signal applied is completely amplified and reproduced without any losses. This can be understood as Faithful Amplification.
The operating point is so chosen such that it lies in the active region and it helps in the reproduction of complete signal without any loss.
If the operating point is considered near saturation point, then the amplification will be as under.

19. Operating Point Continued
If the operation point is considered near cut off point, then the amplification will be as under.

20. Operating Point Continued
Hence the placement of operating point is an important factor to achieve faithful amplification. But for the transistor to function properly as an amplifier, its input circuit (i.e., the base-emitter junction) remains forward biased and its output circuit (i.e., collector-base junction) remains reverse biased.
The amplified signal thus contains the same information as in the input signal whereas the strength of the signal is increased.
Key factors for Faithful Amplification
To ensure faithful amplification, the following basic conditions must be satisfied.
Proper zero signal collector current
Minimum proper base-emitter voltage (VBE) at any instant.
Minimum proper collector-emitter voltage (VCE) at any instant.

23. How to find an operating point?
For finding operating point first we have to find load line points( A and B ) on Ic and Vce. For general transistor biasing circuit, output circuit equation is
Vce = Vcc – IcRc
The output characteristics of this transistor show graph between Ic and Vce. For finding intersecting points of load line with X-axis and Y-axis we take one by one Ic=0 and then Vce=0.
First, we take Ic= 0 so that
Vce = Vcc
This value of point B will be Vcc. If we take Vce=0 then,
Ic = Vcc/ Rc
So the value of point A will be Vcc /Rc.
when we draw this load line, a point at which load line intersecting with Ib is called the operating point or q-point.

24. Question –
In the circuit shown above, (i) if Vcc = 12V and Rc = 6kΩ, draw the d.c load line. What will be the Q-point if zero signal base current is 20μA and β= 50?
Q point example
Here collector-emitter voltage Vce is given by,
Vce= Vcc – IcRc
When Ic = 0 A then Vce= Vcc so Vce=12v
When Vce= 0 V then Ic = Vcc/ Rc. So ic will be 12/2 A = 6 A.
By joining this two points we get load line. Zero signal base current Ib= 20 μA and β is 50. So we have to find an intersecting point of load line with Ib.
Ic = βIb
Ic = 50 X .02 = 1 mA
Zero signal collector-emitter voltage is,
Vce= Vcc – IcRc = 12 – (1mA x 6kΩ )= 6V
So that operating point will be ( Ic, Vce ) = ( 1mA, 6V ).