1

GATE ECE 1995

Subjective

+10

-0

A ROM is to be used to implement the Boolean functions given below:

$${F_1}$$$$(A,\,B,\,C,\,D) = ABCD + \bar A\,\overline B \,\bar C\,\bar D$$

$${F_2}(A,\,B,\,C,\,D) = (A + B)(\bar A\, + \overline B + C)$$

$${F_3}(A,\,B,\,C,\,D) = \sum {13,15 + \sum {3,5} } $$

$${F_1}$$$$(A,\,B,\,C,\,D) = ABCD + \bar A\,\overline B \,\bar C\,\bar D$$

$${F_2}(A,\,B,\,C,\,D) = (A + B)(\bar A\, + \overline B + C)$$

$${F_3}(A,\,B,\,C,\,D) = \sum {13,15 + \sum {3,5} } $$

(a) What is the minimum size of the ROM required?

(b) Determine the data in each location of the ROM.

2

GATE ECE 1994

Subjective

+10

-0

A Boolean function, F , given as sum of product (SOP) terms as F= $$\sum {} $$m(3,4,5,6) with A,B, and C as inputs. The function, F, can be expreeed on the Karnaugh's map shown below.

(1) What will be the minimized SOP expression for F?

(2) Implement this function on an 8 : 1 MUX.

3

GATE ECE 1993

Subjective

+10

-0

Signals A,B,C,D and $$\overline D $$ are available. Using a single 8 - to - 1 multiplexer and no other gate, implement the Boolean function.

$$f(A,B,C,D) = B.C + A.B.\bar D + \bar A.\bar C.\bar D$$

$$f(A,B,C,D) = B.C + A.B.\bar D + \bar A.\bar C.\bar D$$

4

GATE ECE 1989

Subjective

+10

-0

A chemical reactor has three sensors indicating the following conditions:-

(1) Pressure (P) is low or high'

(2) Temperature (T) is low or high' and

(3) Liquid level (L) is low or high.

(1) Pressure (P) is low or high'

(2) Temperature (T) is low or high' and

(3) Liquid level (L) is low or high.

its has two controls - Heater (H) which is either on or off and inlet value (V) which is open or close. The controls are operated as per Table.

(a) Using the convertion High =1, Low = 0, On=1, Off=0, Open=1 and Closed=0, draw the Karnaugh maps for H and V.

(b) Obtain the minimal product of sums expressions for H and V.

(c) Realize the logic for H and V using two 4-input multiplexers with T and L as control inputs. Used T as MSB.

Questions Asked from Combinational Circuits (Marks 10)

Number in Brackets after Paper Indicates No. of Questions

GATE ECE Subjects

Signals and Systems

Representation of Continuous Time Signal Fourier Series Fourier Transform Continuous Time Signal Laplace Transform Discrete Time Signal Fourier Series Fourier Transform Discrete Fourier Transform and Fast Fourier Transform Discrete Time Signal Z Transform Continuous Time Linear Invariant System Discrete Time Linear Time Invariant Systems Transmission of Signal Through Continuous Time LTI Systems Sampling Transmission of Signal Through Discrete Time Lti Systems Miscellaneous

Network Theory

Control Systems

Digital Circuits

General Aptitude

Electronic Devices and VLSI

Analog Circuits

Engineering Mathematics

Microprocessors

Communications

Electromagnetics