I B.Tech - Regular Examinations, June 2009
First Year
ELECTRONIC DEVICES AND CIRCUITS- SET NO: 1
(Regulation 2007)
Time : 3 hours |
Maximam Marks:80 |
Answer any FIVE Questions
1. In a parallel place diode, the cathode and anode are spaced 5mm apart and the
anode is kept at 200V d.c. with respect to cathode. Calculate the velocity and the
distance travelled by an electron after a time of 0.5ns, when
(a) The initial velocity of an electron is zero and
(b) The initial velocity is 2×106 m/s in the direction towards the anode.
2. (a)Explain in detail PN junction energy band diagram of a PN diode.
3. A voltage of 200 cos wt is applied to HWR with load resistance of 5 K
. find the
maximum d.c current component, r.m.s. current, ripple ractor, TUF and rectifier
efficiency.
4.Explain the input and output characteristics of common base transistor configuration.
5.Briefly explain fixed bias with Emitter Feed back. Also find the stability of this
bias.
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.A negative feedback of 0.0005 is applied to an amplifier whose open loop gain is
60dB. If the open loop gain gets reduced by 132%, how much the overall gain gets
altered?
8.(a) A colpitts oscillator is designed with C1 = 100 PF and C2 = 7500 PF. The
inductance is variable. Find the range of inductance value, if the frequency of
oscillation is to vary between 950 KHz and 2050 KHz.
(b) A Hartely oscillator is designed with L2 = 20µH and a variable capacitance.
Find the range of capacitance values. If the frequency of oscillation is varied
between 950 KHz to 2050 KHz.
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