**RGPV Exams Papers IV Sem Digital Circuit & Systems June 2009 **

## B.E. (Fourth semester) EXAMINATION,JUNE, 2009

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

## (DIGITAL CIRCUIT AND SYSTEM – EE/EC/EX-4503)

Note: Attempt any five questions. Each Unit has internal choice question.

1 (a) Encode the following binary digits into -bit seven parity Hamming code :

(i) 0 1 1 1 (ii) 1 0 1 0

(b) Substract (595)_{10} from (378)_{10}

© Convert the following decimal number into gray code:

(i) (87)_{10}? (?) gray code (ii) (1100)_{10}? (?) gray code

(d) What do you mean by Radix ? Also explain reflected code.

2 (a) Simplify the Boolean function using K-method :

F= A’B’C” + B’CD’ + A’B’CD’ + AB’C’+ ABCD

(b) Perform substraction using to 2’s complement method:

1100-110001

© prove the following using De Morgan’s theorem:

(A+B) (C+D) = (A+B) + (C+D)

And hence prove that an OR-AND configuration is equivalent to NOR-NOR configuration. Realize the

logic equation given above using only NOR gates.

3 (a) Explain the working of a 4-bit parallel binary adder .

(b) What do you understand but universal gate? Design all logic gates using universal gates.

4 (a) Compare truth table , excitation table and state table.

(b) Implement full substractor using any logic gate.

© Realize all logic gates using minimum number of NAND gates.

5 (a) Explain the working of Bistable multavibrator.

(b) Define the following:

(i)Propagation delay time of a logic gate

(ii) Figure of merit of digital IC

(iii) Fan-in and Fan-out

(iv) Noise margin

6 (a) Explain Schmitt trigger circuits.

(b) Write short notes on any two of the following:

(i) Asynchronous counter

(ii) Decoder

(iii) Interfacing between TTL to MOS

7 (a) Design a Decade counter.

(b) What is a shift register? Explain.

8 (a) Implement a BCD To excess-3 code converter by using a PLA.

(b) Draw a 5-bit ring counter using J-K flip-flop and explain its working.

9 (a) Draw the block diagram of successive approximation A to D converter and explain its operation.

(b)Explain V-F Converter in brief.

10 (a) explain sample and hold circuit.

(b) What do you mean by A/D and D/A converter?

© What do you understand by Digital Circuit and Systems?