**Scheme – I**

#
Sample Question Paper

Program Name |
: Electronics and Computer Engineering
Program Group |

Program Code |
:
CO/CM/CW/DE/EJ/ET/EN/EX/IE/IS/IC/MU |

Semester
Course Title 70Marks |
: Third : Digital Techniques |

##

Q.1)
Attempt any FIVE of the following. 10 Marks

a) Write
the base of the following number systems: Decimal,
Binary, Octal, and Hexadecimal.

b)
Draw symbol and write the truth table of JK flip
flop.

c)
State the necessity of multiplexer.

d)
Write excitation table of D flip flop.

e)
List any two specifications of IC- DAC
0808.

f)
Draw three variable K-map format.

g) Define
modulus of a counter? Write down the number of flip flops required for mod-5
counter?

##
Q.2)
Attempt any THREE of the following. 12
Marks

a)
For the given figure No. 1, derive the Boolean
expression of Y.

Figure
No. 1

b)
Draw the circuit diagram of BCD to 7 segment
decoder and write its truth table.

c)
Draw the block diagram of Programmable Logic
Array.

d)
Minimize the following expression using
K-map.

f (P, Q,
R, S) = Ξ£ m (0, 1, 4, 5, 7, 8, 9, 12, 13, 15).

##
Q.3)
Attempt any THREE of the following. 12
Marks

a)
Realize the following logic operations using
only NAND gates: AND, OR, NOT.

b) Compare
TTL and CMOS logic families on the basis of following:

i) Propogation delay ii) Power dissipation
iii) Fan-out iv) Basic gate

c) Describe
the operation of 4- bit universal shift register with the help of block
diagram.

d) Calculate
analog output of 4 bit DAC for digital input is 1011. Assume V

_{F S}= 5V.##
Q.4)
Attempt any THREE of the following. 12
Marks

a) Draw
the symbol and write logic expression and truth table of the two input
universal logic gates.

b) Describe
function of full subtractor circuit with its truth table, K-map simplification
and logic diagram.

c)
Design 1: 16 demultiplexer using 1: 4
demultiplexers.

d) Describe
the working of Master-Slave JK Flip-Flop with Truth Table and Logic diagram.

e)
The output of 8 bit DAC varies between +10V and
-10V. Calculate the following:

i)
Resolution ii) Percentage resolution.

##
Q.5)
Attempt any TWO of the following. 12
Marks

a)
Design 3-bit synchronous counter and draw output
waveform.

b) Compare
the following (Any three points)
.

(i) Volatile
with Non-Volatile memory.

(ii)
SRAM with DRAM memory.

c) Convert
the following :

(i) (5C7)

_{16}= (?)_{10}ii) (2598)_{10}= (?)_{16}iii) (10110)_{2}= (?)_{10}= (?)_{16 }##
Q.6)
Attempt any TWO of the following. 12
Marks

a)
Describe the procedure to design MOD-6 counter
using IC 7490 in brief.

b)
Design a four bit BCD adder using IC 7483 and
NAND gates only.

Identify the circuit shown as figure no.2 and explain its working.
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