**RGPV Exams Questions Papers Digital Circuit & Systems Dec 2005**

## B.E. (Fourth semester) EXAMINATION,DEC. 2005

## (Common for EC/EE/EX Engg.)

## (DIGITAL CIRCUIT AND SYSTEM – EE/EC/EX-402)

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

1. (a) Convert the number ( 350.25)_{10} to base 4,8 and 16.

(b) What is BCD? Write BCD representation of decimal number 257.

(c ) Show 8-bit addition of the following decimal number in 2’ complement representation:

45 and 48

68 and 37.

(d) Write gray code for (18)_{10 } and (67)_{10.}

2. (a) Minimize the four variable logic function and release using NAND gate :

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

(b) For a full adder first make a truth table and than using Quine and McCluskey’s method simplify the

expression for some and carry. Also draw the circuit fir NAND-NAND reliasation

3. (a) What is racing in a flip-flop? How it can be avoided? Explain.

(b) Describe the procedure to design MOD X counter . Take any number of X between 0 and 15.

4. (a) Explain serial-in serial-out parallel-in-parallel-out type of registers with the help of circuit diagram.

(b) Explain the working of a bistable multavibrator .

5. (a) Explain TTL and CMOS in detail with circuit diagram.

(b) Explain the operation of a Schmitt trigger

6.(a) Simplify the Boolean function F using the don’t care condition X in product of sum form:

F = A B D + ACD + ABC

X = ABCD + ACD + ABD

(b) Draw and explain an operation of a full subtractor.

7. (a) Explain and discuss any one method of D to A converter.

(b) What do you mean by PLA ? Explain .

8. Write short note on any two of the following:

(a) V-F converter

(b) Look-ahead carry generater

(c ) Interfacing between TTL to MOS.

(d ) Semiconductor memories.