I B.Tech - Regular Examinations, June 2009
First Year
ELECTRONIC DEVICES AND CIRCUITS- SET NO: 4
(Regulation 2007)
Time : 3 hours |
Maximam Marks:80 |
Answer any FIVE Questions
1. An infinitely large parallel plane plates are spaced 0.8 cm apart. The voltage on
one of the plates is raised from 0 to 5 V in 1 ns at a uniform rate with respect to the
other. After this duration, the potential difference between the plates is suddenly
dropped to 0 V and remains the same thereafter. Find
(a) The position of the electron, which started with zero initial velocity from the
negative plate, when the potential difference drops to zero volt,
(b) The total time of transit of the electron from the cathode to the anode.
2.Explain in detail PN junction energy band diagram of a PN diode.
3.(a) Describe transistor shunt regulator.
(b) Calculate the output voltage and zener current in the regulator circuit shown
in Figure 3b.
4.(a) Write the reason why the Ico value is negative for NPN transistor & Ico value
is positive for NPN transistor.
(b) Define base spreading reisitance.
5.A transistor with ß = 50; VBE=0.7V, VCC=22.5V, and RC = 5.6K
is used in
biasing circuit shown in figure 5. It is designed to establish the quiescent point atVCE = 12V, IC = 1.5mA and stability factor S < 3. Find the value of resistor RE1,
R1 and R2.
6.(a) Draw the low frequency hybrid equivalent. Circuit for CE & CB amplifier.
(b) Give the approximate h-parameter conversion formulae for CB and CC con-
figuration in terms of CE.
(c) Give the advantages of h-parameter analysis.
(d) Give the procedure to form the approximate h - model from exact h - model
of amplifier.
7.Draw the practical circuit for voltage series feedback and find the voltage gain,
input impedance & output impedance.
8.Explain briefly about frequency and amplitude stability of oscillators.
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