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C192039 Pages:2

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

THIRD SEMESTER B.TECH DEGREE EXAMINATION(R&S), DECEMBER 2019

Course Code: EC205
Course Name: ELECTRONIC CIRCUITS

PARTA

Answer any two full questions, each carries 15 marks.
Draw an RC differentiator circuit. Give the conditions for an RC circuit to behave
as a differentiator.
Design an integrator for an input frequency of 1kHz.
A high pass RC circuit has a 3dB cut off frequency of 10Hz. Plot the output
waveform of the circuit, if a 20Hz symmetric square wave with 2V peak to peak is
applied to it. Mark the time and voltage levels accurately.
Define stability factor for leakage current. Derive an equation for stability factor
of emitter bias circuit.
For a fixed bias circuit with Rg=300kQ, Rc=2kQ, 9550, Vec=9V, find the Q point
and stability factor.
A silicon transistor with B=50 is used in a voltage divider bias circuit with
Vpr=0.6V, Vec=22.5V and Rc=5.6K. It is desired to establish ಛಿ point at (8.2V,
2.3mA) and required stability factor is ऽ 2 3. Design the voltage divider circuit.
Draw a common base amplifier circuitand show its small signal hybrid 7 model.
Prove that the mid band gain of an emitter follower circuit is approximately equal
to unity.
For a RC coupled amplifier with bypass capacitor, the circuit components are
R,=35.2 1८2, २2=5.83 1൧, 1൦1019. Rg=1K and Rs=0.The transistor parameters
are ۷ 8800< 0.7۷, Va=l00V, and B=100. Determine the Q-point and small signal
voltage gain [Vcc=5V].

PART ‏تا‎

Answer any two full questions, each carries 15 marks.
Explain the terms beta cut off frequency (fg) and unity gain bandwidth (fr) in
relation with short circuit gain of a transistor. Derive an expression for fg and fy in
terms of transistor parameters.

Determine the upper cut-off frequency of a common emitter amplifier

Page 1 of 2

Duration: 3 Hours

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