Download Visvesvaraya Technological University (VTU) BE-B.Tech (Bachelor of Engineering/ Bachelor of Technology) 2020 January [folder1] 3rd Sem 17EC34 Digital Electronics Previous Question Paper
USN
17EC34
Third Semester B.E. Degree Examination, Dec.2019/Jin.2020
Digital Electronics
Time: 3 hrs. Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
U
s
P Module-1
? 1 a. Express the following functions into a canonical form:
,.,
0 f
i
= a + be + bcd
ii) f2 = a(b + c) (b + c + d)
_
?
,,
(08 Marks)
t.11
cz b. Represent the number of days in a month for a non-leap year by a truth cable, indicating the
c.=
output of a invalid inputs if any by '0'. (06 Marks)
dijor j;
?
6
.
S3 c. Simplify the given function using K-map method
ta 0
c oc,
f(abcd) = Ern (1, 2, 4, 11, 13, 14, 15) +d (0, 5, 7, 8, 10).
*E +
(06 Marks)
. cs,
c *C 71-
E d)
L.. .
OR
,i, c
.c o
2 a. Find all prime implicants of the function using Quine-industry method and verify the same
=
by K-map method .f(abcd) = Em (0, 2, 3, 4, 8, 10, 12, 13, 14) (10 Marks)
ai ti
,
c
. a
0 b.
Find minimal sum and minimal product for the incomplete Boolean function using K-map
-
2
.7...
1:1 5
f(abcd) = Em(6, 7, 9, 10, 13) + d E(1, 4, 5, 11, 15). (10 Marks)
cr
U 4.)
7 O
:
CZ
0
c - - - - -
Module-2
-0
C
ct
3 a. Design two bit magnitude comparator. (10 Marks)
. ,
74 b. Design 4:2 priority encoder with a valid output where highest priority is given to the highest
45 73
bit position. (10 Marks)
il
0
O ,-.
a B.
OR
0 F,
,- ,
d-
4 a. Design and realize the Boolean function using IC-74139.
6 .2 fl(ab) = E(0, 2), f2(abc) = E(1, 3, 5, 7). (05 Marks)
a.) 'F v ;
b. Explain how look ahead carry adder circuit will reduce the propagation delay with the help
.
,
..
0
.
c --
c t.
of carry propagate and carry generate function. (08 Marks)
L Q.)
E
1
-/
> , c ? -
C. Implement the Boolean function f(abcd) = E(0, 2, 4, 5, 7, 9, 10, 14) using multiplexers with
0
? to two 4:1 MUX with variable 'a' and 'b' are connected to their select lines in first level and
-E.
c
t -
one 2:1 MUX with variable 'c' connected to its select line in second level. (07 Marks)
c'
3
E
0
. >,
6
.,
Module-3
_4 csi
5 a. With the help of logic circuit and waveforms. Explain switch bouncing applications using
? ?
0
0,
SR latch. (06 Marks)
z
b.
Write the characteristics equation for SR, JK flip flop. (06 Marks)
,:. c.
With neat logic diagram, and waveform. Explain the operation of master-slave J-K flip-flop.
?-_
,,,.,?
....,-- -. ...
(08 Marks)
;,. ... . ..
1 of 2 ..'
/N .-
-'
/- ... /
,i .- ?
., ,7,
,!.,.., .,,? ,
- i .--- -
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@Mt
USN
17EC34
Third Semester B.E. Degree Examination, Dec.2019/Jin.2020
Digital Electronics
Time: 3 hrs. Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
U
s
P Module-1
? 1 a. Express the following functions into a canonical form:
,.,
0 f
i
= a + be + bcd
ii) f2 = a(b + c) (b + c + d)
_
?
,,
(08 Marks)
t.11
cz b. Represent the number of days in a month for a non-leap year by a truth cable, indicating the
c.=
output of a invalid inputs if any by '0'. (06 Marks)
dijor j;
?
6
.
S3 c. Simplify the given function using K-map method
ta 0
c oc,
f(abcd) = Ern (1, 2, 4, 11, 13, 14, 15) +d (0, 5, 7, 8, 10).
*E +
(06 Marks)
. cs,
c *C 71-
E d)
L.. .
OR
,i, c
.c o
2 a. Find all prime implicants of the function using Quine-industry method and verify the same
=
by K-map method .f(abcd) = Em (0, 2, 3, 4, 8, 10, 12, 13, 14) (10 Marks)
ai ti
,
c
. a
0 b.
Find minimal sum and minimal product for the incomplete Boolean function using K-map
-
2
.7...
1:1 5
f(abcd) = Em(6, 7, 9, 10, 13) + d E(1, 4, 5, 11, 15). (10 Marks)
cr
U 4.)
7 O
:
CZ
0
c - - - - -
Module-2
-0
C
ct
3 a. Design two bit magnitude comparator. (10 Marks)
. ,
74 b. Design 4:2 priority encoder with a valid output where highest priority is given to the highest
45 73
bit position. (10 Marks)
il
0
O ,-.
a B.
OR
0 F,
,- ,
d-
4 a. Design and realize the Boolean function using IC-74139.
6 .2 fl(ab) = E(0, 2), f2(abc) = E(1, 3, 5, 7). (05 Marks)
a.) 'F v ;
b. Explain how look ahead carry adder circuit will reduce the propagation delay with the help
.
,
..
0
.
c --
c t.
of carry propagate and carry generate function. (08 Marks)
L Q.)
E
1
-/
> , c ? -
C. Implement the Boolean function f(abcd) = E(0, 2, 4, 5, 7, 9, 10, 14) using multiplexers with
0
? to two 4:1 MUX with variable 'a' and 'b' are connected to their select lines in first level and
-E.
c
t -
one 2:1 MUX with variable 'c' connected to its select line in second level. (07 Marks)
c'
3
E
0
. >,
6
.,
Module-3
_4 csi
5 a. With the help of logic circuit and waveforms. Explain switch bouncing applications using
? ?
0
0,
SR latch. (06 Marks)
z
b.
Write the characteristics equation for SR, JK flip flop. (06 Marks)
,:. c.
With neat logic diagram, and waveform. Explain the operation of master-slave J-K flip-flop.
?-_
,,,.,?
....,-- -. ...
(08 Marks)
;,. ... . ..
1 of 2 ..'
/N .-
-'
/- ... /
,i .- ?
., ,7,
,!.,.., .,,? ,
- i .--- -
c I k
OR
6 a. List the difference between combinational and sequentional circuit. (06 Mari .
b. Explain the operation of clocked SR flip-flop using NAND-gate. s (06 Marks; ,
c. What is the significance of Edge triggering? Explain the working of positive edge triggered
D flip-flop with their function table. (08 Marks)
Module-4
7 a. With neat diagram, explain the operation of universal shift register. (08 Marks)
b. Design 3 bit binary synchronous down counter using JK Flip Flop. Write excition table,
transition table, and logic diagram. (12 Marks)
OR
8 a. What is register? With heat circuit diagram, explain the operation of 4-bit ring counter.
(07 Marks)
b. With logic diagram, sequence table, decoding logic. Explain the operation of mod-7 twisted
ring counter. (07 Marks)
c. Explain the working of 4 bit binary ripple counter using positive edge triggered T-flip-flop
also draw timing diagram, truth table. (06 Marks)
Module-5
9 a. Write the difference between Moore and Mealy model with necessary block diagram.
(08 Marks)
b.
Design asynchronous circuit using positive edge triggered J-K flip-flop with minimal
combinational gating to generate the following sequence. 0-1-2-0: if input X = 0 and
0 ? 2 ? 1? 0; if input X = 1, provide an output which goes high to indicate the non-zero state
in the 0-1-2-0 sequence. Is this a mealy machine? (12 Marks)
OR
10 a. Design a cyclic mod-8 synchronous binary counter using JK flip-flop.
b. Analyze the given sequential circuit show in Fig.Q.10(b) and obtain.
i) Flip-flop Input and Output Equation
ii) Transition Equation
iii) Transition Table (N)
iv) State Table
v) State Diagram.
(10 Marks)
(10 Marks)
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This post was last modified on 28 February 2020