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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 12
6.
An air-filled rectangular waveguide has dimensions 8cm x 10cm . The wavelength of waveguide at frequency 3 GHz
25 cm
100 cm
16.13 cm
23.09 cm
Answer: Option
Explanation:

λc = 2a = 2(10) = 20 cm

= 1.5 GHz

λg = 23.09 cm.

7.
NMOS devices have __________ switching speeds and __________ on-state resistance; as compared with PMOS devices.
slower, higher
faster, lower
faster, higher
slower, lower
Answer: Option
Explanation:

In NMOS devices, we have mobility of electrons than holes in PMOS; consequently higher conductivity and lower on-state resistance.

8.
What is the frequency of pulse at the points a, b, c in the circuit?
3 MHz
7.8 KHz
10 KHz
1 MHz
Answer: Option
Explanation:

Ring counter is N : 1 divider.

Hence ⇒ 1 MHz

Johnson counter is 2N : 1 divider

⇒

Ripple counter 2N : 1

⇒ = 7812.5 ∼ 7.8 kHz

Mod 10 = 4 FF ⇒ 24 = 16.

9.
A lossless transmission line with air dielectric is 6 m long. what is the phase constant?
1p rad/m
2p rad/m
0.2p rad/m
0.1p rad/m
Answer: Option
Explanation:

.

10.
The impulse response h(t) of a linear invariant continuous time system is given by h(t) = exp (- 2t) u(t), where u(t) denotes the unit step function. The frequency response H(ω) of this system in terms of angular frequency ω is given by H(ω)
Answer: Option
Explanation:

H(ω) = e-2t e-jωt

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