Download Visvesvaraya Technological University (VTU) BEB.Tech (Bachelor of Engineering/ Bachelor of Technology) 2020 January [folder1] 3rd Sem 18EC34 Digital System Design Previous Question Paper
18EC34
Third Semester B.E. Degree Examination, Tie&20.191JA11.2020
Digital System Design
Time: 3 hr s. Max. Marks: 100
Note: Answer any FIVE full questions, choosing

ONE full question from each module.
Module1
1 a. Design a combinational circuit to output the 2's complement of a 4bit binary number.
(07 Marks)
b. Identify all prime implicants and essential prime implicants of following function using
Kmap:
f(a. b. c. d) Em (6, 7, 9, 10, 13) + dc(1, 4, 5, 11, 15). Draw the diagram using NAND
. ?.
gates. (07 Marks)
"1,'
2
'
cz = c. Expand the following in to canonical form and represent in decimal form:
i) f
l
= a + be + acid in to minterms
......,... _
. . r,
ii) f2 = a(b +c) (a + c + d) into max terms. (06 Marks)
II
= DC
 7

1

. _ r?I
OR
2 a. Find the minimal sum of the following Boolean function using QuineMeClusky method:
P 1.)
eu c
f(a, b, c, d.)  Em (7, 9, 12, 13, 14, 15) + dc (4, 11). (07 Marks)
?
..
Using Kmap determine minimal product of sum expressions an implement the simplified
0 ?
,..
equation using only NOR gates:
.._ 0
c, f(w, x, y, z) = 7(1, 2, 3, 4, 9, 10) + d(0, 14, 15). (07 Marks)
,,, ,
2 17


C.
Explain briefly Kmap, Incompletely specified functions, essential prime implicants and
7z, 5
Gray code. (06 Marks)
5, =
= ..7
.
4
Module2
, 

t
3 a. Implement the following using 3 to 8 decoder with active low enable and active HIGH
outputs:
5. .0
i) f
i
(a, b, c, d) = I'm (0, h 5, 6, 7, 9, 10, 15)
s
?
,
,
?
L ii) f2(a? b, c) = 7( I. 3, 6, 7) (06 Marks}
..___ g  m
b. Explain 4bit carry lookahead adder with necessary diagram and relevant expressions.
L.,
g ,9
(08 Marks)
7,
3 0
c. Design 4 line to 2 line priority encoder which gives MSB the highest priority and LSB least
priority.
(06 Marks)
5
7
.
,.4. OR
.?.,
? to
4 a. Implement f(a, b, c, d) = DO, 4, 8, 10, 14, 15) using

E.. ' v, i) 8:1 MUX with a, b, c as select lines
O Z. .
i i ) 4:1 MUX
with a, b as select lines.
c.,
(06 Marks)
6
b. Design a two bit magnitude comparator and draw the neat diagram. (08 Marks)
I4 C . Explain the structure of programmable logic arrays (PLA) with an example. (06 Marks)
1.)
__ Module3
't
5 a. Explain clocked SR flip flop using NAND gates with necessary truth table and waveform.
,
,
c (06 Marks)
b. Explain with a neat diagram and truth table, a 4bit SIPO shift register to store binary
, 
._
number 1011. .. ?
(07 Marks)
c.
What is race around condition? Explain JK master slave flip flop with a diagram, function
table andtiming diagram.
(07 Marks)
I oft
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18EC34
Third Semester B.E. Degree Examination, Tie&20.191JA11.2020
Digital System Design
Time: 3 hr s. Max. Marks: 100
Note: Answer any FIVE full questions, choosing

ONE full question from each module.
Module1
1 a. Design a combinational circuit to output the 2's complement of a 4bit binary number.
(07 Marks)
b. Identify all prime implicants and essential prime implicants of following function using
Kmap:
f(a. b. c. d) Em (6, 7, 9, 10, 13) + dc(1, 4, 5, 11, 15). Draw the diagram using NAND
. ?.
gates. (07 Marks)
"1,'
2
'
cz = c. Expand the following in to canonical form and represent in decimal form:
i) f
l
= a + be + acid in to minterms
......,... _
. . r,
ii) f2 = a(b +c) (a + c + d) into max terms. (06 Marks)
II
= DC
 7

1

. _ r?I
OR
2 a. Find the minimal sum of the following Boolean function using QuineMeClusky method:
P 1.)
eu c
f(a, b, c, d.)  Em (7, 9, 12, 13, 14, 15) + dc (4, 11). (07 Marks)
?
..
Using Kmap determine minimal product of sum expressions an implement the simplified
0 ?
,..
equation using only NOR gates:
.._ 0
c, f(w, x, y, z) = 7(1, 2, 3, 4, 9, 10) + d(0, 14, 15). (07 Marks)
,,, ,
2 17


C.
Explain briefly Kmap, Incompletely specified functions, essential prime implicants and
7z, 5
Gray code. (06 Marks)
5, =
= ..7
.
4
Module2
, 

t
3 a. Implement the following using 3 to 8 decoder with active low enable and active HIGH
outputs:
5. .0
i) f
i
(a, b, c, d) = I'm (0, h 5, 6, 7, 9, 10, 15)
s
?
,
,
?
L ii) f2(a? b, c) = 7( I. 3, 6, 7) (06 Marks}
..___ g  m
b. Explain 4bit carry lookahead adder with necessary diagram and relevant expressions.
L.,
g ,9
(08 Marks)
7,
3 0
c. Design 4 line to 2 line priority encoder which gives MSB the highest priority and LSB least
priority.
(06 Marks)
5
7
.
,.4. OR
.?.,
? to
4 a. Implement f(a, b, c, d) = DO, 4, 8, 10, 14, 15) using

E.. ' v, i) 8:1 MUX with a, b, c as select lines
O Z. .
i i ) 4:1 MUX
with a, b as select lines.
c.,
(06 Marks)
6
b. Design a two bit magnitude comparator and draw the neat diagram. (08 Marks)
I4 C . Explain the structure of programmable logic arrays (PLA) with an example. (06 Marks)
1.)
__ Module3
't
5 a. Explain clocked SR flip flop using NAND gates with necessary truth table and waveform.
,
,
c (06 Marks)
b. Explain with a neat diagram and truth table, a 4bit SIPO shift register to store binary
, 
._
number 1011. .. ?
(07 Marks)
c.
What is race around condition? Explain JK master slave flip flop with a diagram, function
table andtiming diagram.
(07 Marks)
I oft
181.
OR
6 a. Explain with an excitation table, the conversion of SR flip flop in to JK and D flip flop.
(06 Marks)
b. Explain the working of 4bit Twisted Ring counter using necessary diagram and waveform.
(07 Marks)
c.
Explain the working of 3bit Asynchronous updown counter with necessary waveform and
truth table. (07 Marks)
Module4
7 a. Design a self correcting synchronous counter using positive edge triggered JK flip flop to
count 0, 1, 2, 4, 5, 6, 0, 1, 2.... Use the state table and state diagram. (10 Marks)
b. Design a clocked sequential circuit which operates according to the state diagram shown in
Fig.Q.7(b). Implement the circuit using negative edge triggered JK flipflop. (10 Marks)
are
oit
Fig.Q.7(b)
OR
8 a. Construct the excitation table, transition table, state table and state diagram for the
sequential circuit shown in Fig.Q.8(a). (10 Marks)
Fig.Q.8(a)
b. Realize synchronous decade counter using Tflipflop and draw the neat diagram. (10 Marks)
Module5
9 a. Design a Melay type sequence detector to detect the sequence of 101 in the given sequence
of001101100101011. (10 Marks)
b. With necessary diagram, explain the concept of serial adder with accumulators. (10 Marks)
OR
10 a. Design a sequential circuit to convert BCD to Excess3 code with state table, state graph and
transition table. (10 Marks)
b. Explain the design of sequential circuit using CPLDs and give CPLD implementation of a
shift register and parallel adder with accumulator.
f
(10 Marks)
Z
.
)
1
3 C

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This post was last modified on 28 February 2020