EC GATE 2008 - Online Test
Q1. Consider the amplitude modulated (AM) signal 
For demodulating the signal using envelope detector, the minimum value of Ac should be
For demodulating the signal using envelope detector, the minimum value of Ac should be
Answer : Option A
Explaination / Solution:
Q2. 
The OPAMP circuit shown above represents a
Answer : Option B
Explaination / Solution:
and from this equation it may be easily seen that this is the standard form of
T.F. of low pass filter
and form this equation it may be easily seen that this is the standard form of
T.F. of low pass filter
Q3. The driving point impedance of the following network is given by
The component values are
Answer : Option D
Explaination / Solution:
Q4. The value of the integral of the function g(x,y) = 4x3 + 10y4 along the straight
line segment from the point (0,0) to the point (1,2) in the x - y plane is
Answer : Option A
Explaination / Solution:
Q5. Two identical NMOS transistors M1 and M2 are connected as shown below.
Vbias is chosen so that both transistors are in saturation. The equivalent gm of
the pair is defied to be 
at constant Vout 
at constant Vout The equivalent gm of the pair is
Answer : Option C
Explaination / Solution:
No Explaination.
Q6. The circuit shown in the figure is used to charge the capacitor C alternately
from two current sources as indicated. The switches S1 and S2 are mechanically
coupled and connected as follows:
Assume that the capacitor has zero initial charge. Given that u(t) is a unit step function , the voltage vc(t) across the capacitor is given by
Answer : Option C
Explaination / Solution:
Q7. Silicon is doped with boron to a concentration of 4 × 1017 atoms cm3. Assume
the intrinsic carrier concentration of silicon to be 1.5 × 1010/cm3 and the value
of kT/q to be 25 mV at 300 K. Compared to undopped silicon, the fermi level
of doped silicon
Answer : Option C
Explaination / Solution:
Q8. A uniform plane wave in the free space is normally incident on an infinitely thick dielectric slab (dielectric constant ε = 9). The magnitude of the reflection coefficient is
Answer : Option C
Explaination / Solution:
Q9. A memory less source emits n symbols each with a probability p. The entropy of the source as a function of n
Answer : Option A
Explaination / Solution:
Q10. Group
I gives two possible choices for the impedance Z in the diagram. The circuit
elements in Z satisfy the conditions R2C2 > R1C1. The transfer functions V0/V1 represents a kind of
controller.
Match the impedances in Group I with the type of controllers in Group II
Group I Group II
Answer : Option B
Explaination / Solution:
