EC GATE 2007 - Online Test
Q1. 
In the following scheme, if the spectrum M(f) of m(t) is as shown, then the spectrum Y(f) of y(t) will be
Answer : Option B
Explaination / Solution:
Q2. In the CMOS inverter circuit shown, if the trans conductance parameters of the
NMOS and PMOS transistors are
and their threshold voltages ae 
the current I is
and their threshold voltages ae the current I is
Answer : Option D
Explaination / Solution:
Q3. During transmission over a certain binary communication channel, bit errors occur independently with probability p. The probability of AT MOST one bit in error in a block of n bits is given by
Answer : Option C
Explaination / Solution:
Q4. In a GSM system, 8 channels can co-exist in 200 kHz bandwidth using TDMA.
A GSM based cellular operator is allocated 5 MHz bandwidth. Assuming a
frequency reuse factor of 1/5, i.e. a five-cell repeat pattern, the maximum number
of simultaneous channels that can exist in one cell is
Answer : Option B
Explaination / Solution:
Q5. The figure shows the high-frequency capacitance - voltage characteristics of Metal/Sio2/silicon (MOS) capacitor having an area of 1 × 10-4 cm2. Assume that the permittivities (ε0εr) of silicon and Sio are 1 × 10-12 F/cm and 3.5 × 10-13 F/ cm respectively.
The gate oxide thickness in the MOS capacitor is
Answer : Option A
Explaination / Solution:
Q6. In a Direct Sequence CDMA system the chip rate is 1.2288 × 106 chips per
second. If the processing gain is desired to be AT LEAST 100, the data rate
Answer : Option A
Explaination / Solution:
Q7. The figure shows the high-frequency capacitance - voltage characteristics of Metal/Sio2/silicon (MOS) capacitor having an area of 1 × 10-4 cm2. Assume that the permittivities (ε0εr) of silicon and Sio are 1 × 10-12 F/cm and 3.5 × 10-13 F/ cm respectively.
The maximum depletion layer width in silicon is
Answer : Option B
Explaination / Solution:
Q8. An air-filled rectangular waveguide has inner dimensions of 3 cm × 2 cm.
The wave impedance of the TE2 mode of propagation in the waveguide at a
frequency of 30 GHz is (free space impedance η0 = 377Ω)
Answer : Option C
Explaination / Solution:
Q9.
The figure shows the high-frequency capacitance - voltage characteristics of Metal/Sio2/silicon (MOS) capacitor having an area of 1 × 10-4 cm2. Assume that the permittivities (ε0εr) of silicon and Sio are 1 × 10-12 F/cm and 3.5 × 10-13 F/ cm respectively.
Consider the following statements about the C − V characteristics plot :
S1 : The MOS capacitor has as n-type substrate
S2 : If positive charges are introduced in the oxide, the C − V polt will shift to the left.
Then which of the following is true?
Answer : Option C
Explaination / Solution:
Depletion region will not be formed if the MOS capacitor has n type substrate but from C-V characteristics, C reduces if V is increased. Thus depletion region must be formed. Hence S1 is false
If positive charges is introduced in the oxide layer, then to equalize the effect the applied voltage V must be reduced. Thus the C − V plot moves to the left. Hence S2 is true.
Q10. The
field in a rectangular waveguide of inner dimension a × b is given by 
field in a rectangular waveguide of inner dimension a × b is given by Where H0 is a constant, and a and b are the dimensions along the x − axis and
the y − axis respectively. The mode of propagation in the waveguide is
Answer : Option A
Explaination / Solution:
