EC GATE 2013 - Online Test
Q1. In the circuit shown below, the knee current of the ideal Zener dioide is 10 mA
. To maintain 5 V across RL, the minimum value of RL in Ω and the minimum
power rating of the Zener diode in mW, respectively, are
Answer : Option B
Explaination / Solution:
No Explaination.
Q2. The small-signal resistance 
in kW offered by the n-channel
MOSFET M shown in the figure below, at a bias point of VB = 2V is (device
data for M: device transconductance parameter 
, threshold voltage VTN = 1V, and neglect body effect and channel length
modulation effects)
in kW offered by the n-channel
MOSFET M shown in the figure below, at a bias point of VB = 2V is (device
data for M: device transconductance parameter , threshold voltage VTN = 1V, and neglect body effect and channel length
modulation effects)
Answer : Option A
Explaination / Solution:
No Explaination.
Q3. The ac schematic of an NMOS common-source state is shown in the figure
below, where part of the biasing circuits has been omitted for simplicity. For the
n-channel MOSFET M, the transconductance 
and body effect
and channel length modulation effect are to be neglected. The lower cutoff
frequency in HZ of the circuit is approximately at
and body effect
and channel length modulation effect are to be neglected. The lower cutoff
frequency in HZ of the circuit is approximately at
Answer : Option A
Explaination / Solution:
No Explaination.
Q4.
Two systems with impulse responses h1(t) and h2(t) are connected in cascade. Then the overall impulse response of the cascaded system is given by
Answer : Option C
Explaination / Solution:
If the two systems with impulse responseh1(t) and h2(t) are connected in cascaded configuration as shown in figure, then the overall response of the system is the convolution of the individual impulse responses.
Q5. For a periodic signal 
the fundamental frequency in rad/s
the fundamental frequency in rad/s
Answer : Option A
Explaination / Solution:
Given, the signal
Q6. A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles
Answer : Option C
Explaination / Solution:
Let A denotes the position of switch at ground floor and B denotes the position of switch at upper floor. The switch can be either in up position or down position.Following are the truth table given for different combinations of A and B
When the switches A and B are both up or both down, output will be zero (i.e.Bulb will be OFF). Any of the switch changes its position leads to the ON state of bulb. Hence, from the truth table, we get
i.e., the XOR gate
Q7.
For 8085 microprocessor, the following program is executed.
MVI A, 05H;
MVI B, 05H;
PTR: ADD B;
DCR B;
JNZ PTR;
ADI 03H;
HLT;
At the end of program, accumulator contains
Answer : Option A
Explaination / Solution:
The program is being executed as follows
MVI A, 0.5H; A = 05H
MVI B, 0.5H; B = 05H
At the next instruction, a loop is being introduced in which for the instruction “DCR B” if the result is zero then it exits from loop so, the loop is executed five times as follows :
i.e., A = 05 + 05 + 04 + 03 + 02 + 01 = 144
At this stage, the 8085 microprocessor exits from the loop and reads the next instruction. i.e., the accumulator is being added to 03 H. Hence, we obtain A = A + 03 H = 14 + 03 = 17 H
Q8. Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the
chosen operating frequency. Their respective resistances are R1 and R2. When
connected in series, their effective Q factor at the same operating frequency is
Answer : Option C
Explaination / Solution:
The quality factor of the inductances are given by
So, in series circuit, the effective quality factor is given by
Q9.
Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k, k > 0, the elements of the corresponding star equivalent will be scaled by a factor of
Answer : Option B
Explaination / Solution:
In the equivalent star connection, the resistance can be given as
Q10. The transfer function 
Answer : Option D
Explaination / Solution:
For the given capacitance, 
in the circuit, we have the reactance.
in the circuit, we have the reactance.