Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Summer 4th Sem 2140910 Digital Electronics Previous Question Paper

Seat No.: ________

Enrolment No.___________

**GUJARAT TECHNOLOGICAL UNIVERSITY**

**BE - SEMESTER? IV EXAMINATION ? SUMMER 2020**

**Subject Code: 2140910**

**Date:04/11/2020**

**Subject Name: Digital Electronics**

**Time: 10:30 AM TO 01:00 PM Total Marks: 70**

**Instructions:**

**1. Attempt all questions.**

**2. Make suitable assumptions wherever necessary.**

**3. Figures to the right indicate full marks.**

**MARKS**

**Q.1**

**(a)**Convert (53.625)10 into an equivalent binary number.

**03**

**(b)**Compare 1's complement and 2's complement methods. Calculate 28 -19

**04**

using 2's complement method.

**(c)**State and prove DeMorgan's theorems with necessary figures and truth tables.

**07**

**Q.2**

**(a)**Prove that a positive-logic AND gate is a negative-logic OR gate.

**03**

**(b)**Explain the characteristics of digital logic families.

**04**

**(c)**Simplify the following Boolean expressions using K-maps:

**07**

(i) f = m(1,3,5,8,9,11,15),+,d(2,13)

(ii) F = M(1,2,3,8,9,10,11,14)

**?**d(7,15)

**OR**

**(c)**Simplify the following Boolean expressions using Quine-McKluskey method:

**07**

f =

*C*

*B*

*A*

*D*

*C*

*B*

*A*

*D*

*D*

*C*

*B*

*A*

*D*

*C*

*AB*

*C*

*AB D*

**Q.3**

**(a)**Perform BCD addition of 91 and 81

**03**

**(b)**Compare combinational and sequential logic circuits

**04**

**(c)**

Write a short note on Gray code

**07**

**OR**

**Q.3**

**(a)**Explain even and odd parity codes.

**03**

**(b)**Design and analyze the working of a 1-bit comparator using logic gates

**04**

**(c)**

Describe the working of look ahead adder circuit.

**07**

**Q.4**

**(a)**Explain the full adder circuit.

**03**

**(b)**Discuss the working of 3:8 decoder circuit.

**04**

**(c)**

Describe the working of 4:1 multiplexer. State the advantages of multiplexers.

**07**

1

**OR**

**Q.4**

**(a)**Differentiate between synchronous and asynchronous counters

**03**

**(b)**Explain the working of clocked RS flip-flop.

**04**

**(c)**

Write a short note on applications of shift registers.

**07**

**Q.5**

**(a)**Explain in brief universal shift register.

**03**

**(b)**Draw and explain the circuit of R-2R ladder.

**04**

**(c)**Write a short note on ring counter

**07**

**OR**

**Q.5**

**(a)**State the advantage of a ripple counter

**03**

**(b)**Define the following terms of DAC:

**04**

(i) Accuracy (ii) Resolution (iii) Linearity (iv) Settling time

**(c)**

Explain (i) Static RAM (ii) Dynamic RAM

**07**

*****************

2

This post was last modified on 04 March 2021