## Digital Electronics Question Paper of 3rd Semester ECE16 Download Previous Years Question Paper 4

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Total No. Of Questions : 9]
EC-205
Digital Electronics
(B.Tech., 3rd Semester, 2063)
Time : 3 hrs
Note – This paper consists of Three Sections. Sections   A is compulsory. Answer any four questions from Section –B and any Two questions from Section C.

Section –A
1.                 Answer briefly the following questions:

a.                 Give the binary and hexadecimal equivalent of decimal number (492.75).

b.                 Perform the subtractions 73-117 using 2 ‘s complement method.

c.                  Simplify the Boolean expression:
F = D(A+C) (A+BD)+ACD,
Using logic rules.

d.                 Write the truth take of a 3-input XOR gate.

e.                  Find the simplified POS form of faction
F(X,Y,Z) =Ʃ (0,1,3,7)

f.                   Simplify the faction

F(w,x,y,z) =m4+m5+m7+m8+m9+m11+m12+m15)

Using K- map

g.                 Differentiate between demultiplexer and decoder.

h.                 Implement a full subtract or with two 4:1 multiplexers.

i.                   Differentiate between static RAM and dynamic RAM.

j.                   Make comparisons of TTL and ECL logic families.

Section –B

2.                 Design a Excess-3 to BCD code converter using minimum number of NAND gates.
3.                 Represent the Boolean expression:

F(A,B,C) = (A+C) (B+C)(A+B)

In its canonical POS and SOP forms.

4.                 Explain the operation of Master/Slave J-K flip-f lop. List its advantages.
5.                 Describe the working of successive approximation A/D converter.
6.                 Construct a 4-bit asynchronous up/down counter and explain its working with the help of
timing diagram.

Section –C

7.                 Minimize the Boolean expression :

F(A,B,C,D,E) = M (6,7,11,13,14,17,20,25,28,29,30)

8.                 Design a  mod 5 counter and, hence, construct the logic diagram of a decade counter.

9.

a.                 Design a combination circuit that compares two 2-bit numbers A and B for equality.

b.                 Explain briefly the charge –coupled device (CCD ) memory.