I B.Tech - Regular Examinations, June 2009
First Year
BASIC ELECTRONIC DEVICES AND CIRCUITS - SET NO: 4
(Regulation 2007)
Time : 3 hours |
Maximam Marks:80 |
Answer any FIVE Questions
1. (a) Derive an expression for magnetic deflection sensitivity of C.R.O.
(b) An electron is injected with an initial velocity Vox of 4 × 106 m/sec halfway
between two large parallel plates 0.5 cm apart. The XZ plane is parallel to
the plates. There is a voltage of 200V impressed between the plates, and a
magnetic field of 10 mwb/m2 perpendicular to the plates, directed from the
positive to the negative plate. Where does the electron strike the positive
plate and with what velocity?
2.(a) Determine the resistivity of Germanium:
i. in intrinsic condition at 300 0K
ii. with donor impurity of 1 in 107
iii. with acceptor impurity of 1 in 108
Given for germanium at room temperature. ni = 2.5 × 1013/cm3; µp
= 1800 cm2/V-sec, µn = 3800 cm2/V-sec and number of Germanium
atoms/cm3 = 4.4 × 1022.
(b) Compare Avalanche and Zener breakdown.
3.(a) Explain why a bridge rectifier is preferred over a centre-tap rectifier. Give
circuit diagrams.
(b) A diode has an internal resistance of 20
and 1000
load from a 110V rms
source of supply. Calculate:
i. the efficiency of rectification
ii. the percentage regulation from no load to full load.
4. (a) Compare JFET and MOSFET with respect to various features.
(b) Draw the biasing circuit suitable for JFET and if the JFET is replaced by a
MOSFET for what mode of operation it is valid and explain about the function
of each component used in the circuit.
5. (a) Compare the advantages and disadvantages of biasing schemes.
(b) Calculate the quiescent current and voltage of collector to base bias arrange-
ment using the following data:
Vcc =10V, Rb=100K
, Rc=2K
, ß=50 and also specify a value of Rb so that
Vce=7V
6. Obtain CB h parameters in terms of CE h parameters.
7.(a) Explain how the nonlinear distortion can be reduced by using negative feed-
back in an amplifier.
(b) Calculate voltage gain, input impedance and output impedance of a CE am-
plifier with Voltage-Series negative feedback.
8.(a) Consider the two section RC network shown in figure 8a. Find the Vi/Vf ’
function, and verify that it is not possible to obtain 1800phase shift with a
finite attenuation.
(b) State the similarities and differences between series and parallel resonance
crystal oscillator circuits.
|