1
GATE ECE 2000
Subjective
+5
-0
The operating conditions (ON = 1, OFF = 0) of three pumps (x,y,z) are to be
monitored. x = 1 implies that pump X is on. It is required that the indicator (LED)
on the panel should glow when a majority of the pumps fail.
(a) Enter the logical values in the K-map in the format shown in figure 3(a). Derive
the minimal Boolean sum-of-products expression whose output is zero when a majority of the pumps fail.
(b) The above expression is implemented using logic gates, and point P is the
output of this circuit, as shown in figure 3(b). P is at 0 V when a majority of the pumps fails and is at 5 V otherwise. Design a circuit to drive the LED using this output. The current through the LED should be 10 mA and the voltage drop across it is 1V. Assume that P can source or sink 10 mA and a 5 V supply is available.
2
GATE ECE 1993
Subjective
+5
-0
The truth table for the output Y in terms of three inputs A, B and C are given in
table. Draw a logic circuit realization using only NOR gates.
Questions Asked from Logic Gates (Marks 5)
Number in Brackets after Paper Indicates No. of Questions
GATE ECE Subjects
Network Theory
Control Systems
Electronic Devices and VLSI
Analog Circuits
Digital Circuits
Microprocessors
Signals and Systems
Representation of Continuous Time Signal Fourier Series Discrete Time Signal Fourier Series Fourier Transform Discrete Time Signal Z Transform Continuous Time Linear Invariant System Transmission of Signal Through Continuous Time LTI Systems Discrete Time Linear Time Invariant Systems Sampling Continuous Time Signal Laplace Transform Discrete Fourier Transform and Fast Fourier Transform Transmission of Signal Through Discrete Time Lti Systems Miscellaneous Fourier Transform
Communications
Electromagnetics
General Aptitude