# RGPV Exams Questions Papers IV SEM – Digital Circuit & systems – June -2006

B.E. (Fourth semester) EXAMINATION,MAY,JUNE, 2006

(Common for EC/EE/EX Engg.)

(DIGITAL CIRCUIT AND SYSTEM)

(EE/EC/EX-4503)

Note:     Attempt  any five questions. All question carry equal marks. Assume any missing data.

1.  (a) Convert the number (210.25)10 to base 2,8,16.

(b) Show 8-bit addition of these decimal number in 2’s complement the presentation:

(i) 52 and 67

(ii) 57 and -82

(c ) State dulity theorem .

(d) Write gray code and BDC code for (18)10  .

(e) At  the following numbers :

(i) ABC + CDE   (ii) (77)8 +(107)8

2. (a) Realize the following gates using minimum number of NAND gates :

AND, OR, NOT,NOR,EX-OR

(b) Express the following  in some of minterms and product of maxterm from :

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

F (x,y,z) =1

3. (a) Minimize the 04 variable logic function and release using NOR gate :

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

(B) Use De morgan’s theorem to convert the Boolean expression :

_______________

ABCD + ABCD = Y

To its max  terms from and draw the logic diagram.

(b) Implement a full adder using a multiplexer

5. (a) Explain the working of J-K flip-flop.

(b) Explain the operation of BCD counter.

6. (a) Design a mode -9 counter.

(b) Explain the working of a monostable multavibrator.

7. Write short notes on any two of the following:

(i) CMOS logic families

(ii) Asynchronous  counter

(iii) Sample and hold circuit

(iv) D/A converter