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Reg No.:_. Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD SEMESTER B.TECH DEGREE EXAMINATION(S), MAY 2019
Course Code: EC205
Course Name: ELECTRONIC CIRCUITS (EC,AE)
Max. Marks: 100 Duration: 3 Hours

PARTA
Answer any two full questions, each carries 15 marks. Marks

1 a) Define stability factor for 8 variation. Derive the expression for stability factor for (7)
leakage current of voltage divider biasing circuit.

b) Using hybrid 7 model, obtain the expression for input impedance, output (8)
impedance and mid band voltage gain of a common collector amplifier.

2 a) Derive the condition that must be satisfied by a RC circuit to behave as 8 (5)
differentiator. Design a differentiator circuit to differentiator a square wave of
2KHz frequency.

b) Sketch the response of a RC low pas circuit to a pulse input if RC>> tpand RC<< (3)
tp.

c) Draw a two stage CE cascade amplifier. Derive an expression for its input (7)
resistance, output resistance and voltage gain.

3 a) Draw the circuit of CE voltage amplifier with potential divider bias .Mention use (7)
of each component in it. What do you mean by half power points in its frequency
response?

b) Calculate the small signal voltage gain, input impedance and output impedance of (8)
common emitter amplifier having Ri=56K, 12-1516, Rc=2K, Re=1K, Rs=0.5K,
Vcec=20V, Vpe=0.7V, ٠7 ‏ممحم‎ and B=50

PART छ
Answer any two full questions, each carries 15 marks.

4 a) Draw the high frequency hybrid ர equivalent model of BJT. Derive an expression (5)
for short circuit gain

b) Outline Millers Theorem in a two port electrical circuit. (3)

c) Explain series - series feedback topology with neat block diagram. Derive the (7)
expression for net input and output impedance.

5 a) Draw the small signal high frequency hybrid 7 model of a common emitter (8)

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