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Roll No.
Total No. of Pages : 02
Total No. of Questions : 09
B.Tech.(EIE) (2011 & Onwards) (Sem.?4)
DIGITAL ELECTRONICS
Subject Code : EC-204
M.Code : 57011
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1.
SECTION-A is COMPULSORY consisting of TEN questions carrying T WO marks
each.
2.
SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3.
SECTION-C contains T HREE questions carrying T EN marks each and students
have to attempt any T WO questions.

SECTION-A
1.
Answer briefly :

a) Covert the binary number 1011001011 into (a) octal (b) hexadecimal

b) Convert gray code 101011 into its binary equivalent?

c) Subtract (111001)2 from (101011)2 using 2's compliment method?

d) What do you mean by positive and negative logic?

e) Draw the logic diagram for logic equation Y = (A + B).C.
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f) Give the comparison between PROM and PLA.

g) What is race around condition in flip-flops?

h) The tpd for each flip-flop is 50 ns determine the maximum operating frequency MOD-
32 ripple counter?

i) Give the specifications of A/D converters?

j) Why totem pole outputs cannot be connected together?

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SECTION-B
2.
Simplify the given logic equation using Boolean algebra.
Y P PQR Q R
3.
Minimize the following using K-map
f ( ,
w x, y, z)
(0,1,5, 7,8,14)
d (2,11)
1




and implement the minimized function using only NAND gates.
4.
Explain the principle of operation of a dual slope ADC. How is it advantageous over
ramp type ADC?
5.
Explain the working of a full subtractor with neat diagram and truth table.
6.
Draw the circuit diagram of a 4-bit serial in/serial out shift register using D flip-flops.
Also draw its timing diagram.

SECTION-C
7.
Explain the basic circuits of ECL and tristate logic. Compare TTL and ECL with respect
to fan-in, fan-out, noise margin and propagation delay time.
8.
a) Explain the operation of successive approximation type of ADC.

b) If Q output of a D type flip-flop is connected to D input, it acts as a toggle switch
verify?
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9.
Write short notes on Any Two :

a) SR flip-flop

b) PLA

c) Gray code and Excess-3-code.

NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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