Electronics and Communication Engineering - Exam Questions Papers

6. 

In a certain network not containing any dependent sources, number of nodes = 4 and number of branches is equal to 6.

A. 4
B. 2
C. 3
D. 5

Answer: Option C

Explanation:

No. of independent loop currents is 6 - 4 + 1 = 3.


7. 

The following statements are true with respect to "Cascode Amplifier".

  1. The reduction in h12 and Miller capacitance result in negligible reverse internal feedback.
  2. A's is large loads cannot be connected.
  3. As a narrow band amplifier, it provides small range of cμ is reduced.
  4. As a narrow band amplifier it provides small range of frequencies parameters the effect of cμ reduces.

A. only 1
B. only 1 and 4
C. only 2 and 4
D. only 1 and 3

Answer: Option B

Explanation:

Cascode is a wide band amplifier and it provides wide range of frequencies than CE stage and as is large, large loads can be connected.


8. 

A 4 cm by 3 cm rectangular waveguide with air cavity, is operating at 12 GHz with TE11 mode. The cut-off frequency is:

A. 6.25 GHz
B. 4.75 GHz
C. 1.5 GHz
D. 8.75 GHz

Answer: Option A

Explanation:

.


9. 

For a bipolar transistor, avalanche multiplication factor depends on __________ .

A. VCE
B. VCB
C. VBE
D. none of these

Answer: Option B

Explanation:

Avalanche multiplication factor

where, βVCBO = collector - emitter breakdown voltage with open circuited base.


10. 

In the following transistor circuit VBE = 0. 7 V, rc = 25mV/IE, and β and the capacitance are very large

The mid-band voltage gain of the amplifier is approximately

A. - 180
B. - 120
C. - 90
D. - 60

Answer: Option D

Explanation:

Midband voltage gain =

R'L = 3k || 3k = RC || RL = 1.5k

Thus .