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Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD SEMESTER B.TECH DEGREE EXAMINATION, DECEMBER 2018

Course Code: EC205
Course Name: ELECTRONIC CIRCUITS (EC, AE)
Max. Marks: 100 Duration: 3 Hours

PART A
Answer any two full questions, each carries 15 marks. Marks
1 a) Define stability factor for leakage current and derive its general expression. Derive (8) the
expression for stability factor for leakage current of emitter stabilized biasing circuit.
b) Draw the small signal low frequency hybrid 7 model for common emitter (7)
configuration. Derive the expression for voltage gain, input and output impedance.
2 9) Derive the condition that must be satisfied by a RC circuit to behave as a (5) integrator.
Design an integrator circuit to integrate a square wave of 2KHz frequency.
b) Sketch the response of a RC high pass circuit to a pulse input if RC>> tp and (3) RC<<
tp.
€) Determine the bias voltage Vcr, current Ic and stability factor Sico for the voltage (7)
divider configuration with Vcc=20V, Vpe=0.7V, Ri=30K, R2=4K, Rc=3K, Re=0.5K and
B=120.
3 a) Calculate the small signal voltage gain, input impedance and output impedance of (8)
emitter follower having Ri=50K, Ro2=10K, Re=2K, Rs=0.5K, ‏۷۰ح۷‎
‎Vpe=0.7V, Va=80V and 9550
b) Using hybrid 7 model, obtain the expression for input impedance, output (7) impedance
and mid band voltage gain of a common emitter amplifier.
PART B
Answer any two full questions, each carries 15 marks.

4 a) With neat diagram explain cascode amplifier and its main characteristics. (7)

b) Explain shunt - shunt feedback topology with neat diagram. Derive the expression for net (8)
input and output impedance.

5 a) With the small signal high frequency hybrid 7 model of a common emitter (8)
amplifier without bypass capacitor and derive the expression for upper cut off

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