EC GATE 2009 - Online Test
Q1.
For a message signal 
and carrier of frequency fc which of thefollowing represents a single side-band (SSB) signal ?
Answer : Option C
Explaination / Solution:
Q2.
Consider the following two statements about the internal conditions in a n - channel MOSFET operating in the active region.
S1 : The inversion charge decreases from source to drain
S2 : The channel potential increases from source to drain.
Which of the following is correct?
Answer : Option D
Explaination / Solution:
Both S1 and S2 are true and S2 is a reason for S1.
Q3. The peak electric field in the device is
Answer : Option B
Explaination / Solution:
The peak electric field in device is directed from p to n and is 
Q4.
For small increase in VG beyond 1V, which of the following gives the correct description of the region of operation of each MOSFET
Answer : Option D
Explaination / Solution:
For small increase in VG beyond 1 V the n - channel MOSFET goes into saturation as VGS + ive and p - MOSFET is always in active region or triode region.
Q5. The time domain behavior of an RL circuit is represented by 
For an initial current of
For an initial current ofFor an initial current of 
the steady state value of the current is given by
the steady state value of the current is given by
Answer : Option A
Explaination / Solution:
Steady state all transient effect die out and inductor act as short circuits and forced response acts only. It doesn’t depend on initial current state. From the given time domain behavior we get that circuit has only R and L in series with v0 Thus at steady state 
Q6. Consider a system whose input x and output y are related by the equation 
where h(t) is shown in the graph.
Which of the following four properties are possessed by the system ?
BIBO : Bounded input gives a bounded output.
Causal : The system is causal,
LP : The system is low pass.
LTI : The system is linear and time-invariant.
where h(t) is shown in the graph.Which of the following four properties are possessed by the system ?
BIBO : Bounded input gives a bounded output.
Causal : The system is causal,
LP : The system is low pass.
LTI : The system is linear and time-invariant.
Answer : Option B
Explaination / Solution:
Here h(t) ! 0 for t < 0. Thus system is non causal. Again any bounded input x(t) gives bounded output y(t). Thus it is BIBO stable.
Q7.
A communication channel with AWGN operating at a signal to noise ration SNR >> 1 and bandwidth B has capacity C1. If the SNR is doubled keeping constant, the resulting capacity C2 is given by
Answer : Option B
Explaination / Solution:
Q8. In a microprocessor, the service routine for a certain interrupt starts from a fixed location of memory which cannot be externally set, but the interrupt can be delayed or rejected Such an interrupt is
Answer : Option D
Explaination / Solution:
Vectored interrupts : Vectored interrupts are those interrupts in which program control transferred to a fixed memory location.
Maskable interrupts : Maskable interrupts are those interrupts which can be rejected or delayed by microprocessor if it is performing some critical task.
Q9. 
A transmission line terminates in two branches, each of length 
as shown. The branches are terminated by 50W loads. The lines are lossless and have the characteristic impedances shown. Determine the impedance Zi as seen by the source.
as shown. The branches are terminated by 50W loads. The lines are lossless and have the characteristic impedances shown. Determine the impedance Zi as seen by the source.
Answer : Option D
Explaination / Solution:
The transmission line are as shown below. Length of all line is 
Q10. The magnitude plot of a rational transfer function G(s) with real coefficients is shown below. Which of the following compensators has such a magnitude plot ?
Answer : Option C
Explaination / Solution:
This compensator is roughly equivalent to combining lead and lad compensators in the same design and it is referred also as PID compensator.
