B.E. (Fourth semester) EXAMINATION, June. 2004
(Common for EC/EE/EX Engg.)
(DIGITAL CIRCUIT AND SYSTEM)
Note: Attempt any five questions. All question carry equal marks.
1. (a) Convert the following :
(i) (010011110111.1101)2 to Hexadecimal.
(ii) (327.4)8 to its 8s complement and 7s complement.
(iii) (1101101)2 and (1001000)2 gray code
(iv) Solve using 2s complement:
(1110100.11)2 – (0110101.1)2
(b) Find the equivalent of the following equation;
F = u + _ VW’ + X (Y’ + Z)’
(c ) Simplify the logic expression using postulates of Boolean Algebra:
S=A (B’ + C)’ (BC)’
2. (A) Explain ‘’ minterm’ and don’t care term’
(b) Minimize the expression using K – map and implement using Nand gates only:
F (A,B,C,D) = ? (2,3,4,5,13,15) + ? d (8,9,10,11)
3. (a) Make a 4 – input NAND gate using 2 –input NAND gates.
(b) Prove EX-OR gate is an odd gate hence can be used foe parity checking
(c ) Design a full-substracter and relies the subs tractor using a decoder.
4. (a) Explain CNOS logic with its merits and demerits .
(b) Draw the logic diagram, construct the excitation table and give the characteristics equation and
explain the working of a J-K flip-flop.
5. (A) Design a self starting divide by 3 counter , Represented by the state diagram shown in the
following figure :
(b) Design BCD to excess-3 code converter circuit and draw the logic diagram.
6. (a) What is multiplexer tree ? Why it is needed? Design a 32×1 multiplexer using 8×1 and 4×1
(b) Implement the given Boolean function with 8×1 multiplexer:
F (A,B,C,D) = ? m (0,3,5,6,8,9,10,12,15)
7. Discuss any two of the following:
(ii) V-F converter
(iii) Schmitt trigger circuit
8. Write short notes on any three of the following :
(i) Shift Resister
(iii) Asynchronous counters
(iv) Master-slave flip-flop