Jawaharlal Nehru Technological University Kakinada 2007 B.Tech Electronics and Instrumentation Engineering PULSE AND DIGITAL CIRCUITS (4) - Question Paper

Code No: R059210202 Set No. 1
II B.Tech I Semester Regular Examinations, November 2007
PULSE AND DIGITAL CIRCUITS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Electronics & Instrumentation Engineering
and Electronics & Telematics)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks
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1. (a) Prove that an RC circuit behaves as a reasonably good integrator if RC > 15T,
Where T is the period of an input ‘Em sin ?t'.
(b) What is the ratio of the rise time of the 3 parts in cascade to the rise
time of Single part of low pass RC circuit. [8+8]
2. (a) Draw the circuit diagram of slicer circuit using Zener diodes and discuss its
operation with the help of its transfer characteristic.
(b) Draw the circuit diagram of emitter coupled clipper. Draw its transfer charac-
teristics indicating all intercepts, slopes and voltage levels derive the necessary
equations. [8+8]
3. (a) discuss the terms pertaining to transistor switching characteristics.
i. Rise time.
ii. Delay time.
iii. Turn-on time.
iv. Storage time.
v. Fall time.
vi. Turn-off time.
(b) provide the expression for risetime and falltime in terms of transistor parameters
and operating currents. [6+10]
4. In the nonsaturated binary shown in figure 4, the avalanche diodes D1 and D2 are
nominally identical, as are diodes D3 and D4. The breakdown voltage V?Z of D3
and D4 is larger than the breakdown voltage VZ of D1 and D2. Verify that the
transistors do not enter the saturation region. presume that D3 and D4 are always
in the breakdown region and that either D1 or D2 but not both, is in the breakdown
region. Then verify these assumptions. [16]
1 of 2
Figure 4
5. (a) Draw and clearly indicate the restoration time and flyback time on the typical
waveform of a time base voltage.
(b) Derive the relation ranging from the slope, transmission and displacement errors
(c) discuss how UJT is used for sweep circuit? [6+4+6]
6. (a) What do you mean by synchronization ?
(b) What is the condition to be met for pulse synchronization?
(c) Compare sine wave synchronization with pulse synchronization? [4+6+6]
7. (a) Why are sampling gates called Selection circuits?
(b) elaborate the advantages of unidirectional sampling gates?
(c) elaborate the applications of sampling gates? [6+4+6]
8. (a) With the help of circuit diagram discuss the purpose of clamping diode in a
positive diode AND gate.
(b) discuss the effect of and diode capacitance on the output pulse of diode AND
gate. [8+8]
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Earning:   Approval pending.