Gate 1991, 2001 Questions on Electronic Devices

Gate 1991 (1 mark question):

Question 1:

The Early effect in the bipolar junction transistor is caused by

a)fast turn – on

b)fast turn – off

c)large collator – base reverse bias

d)large emitter – base forward bias

Answer : c

Explanation: Due to reverse bias of collector junction effective base width is less than metallurgical base width and this called Early effect.

Gate 2001(1 mark question) :

Question 2:

MOSFET can be used as a

a)current controlled capacitor

b)voltage controlled capacitor

c)current controlled inductor

d)voltage controlled inductor

Answer : b

Explanation:

Question: 3

The effective channel length of MOSFET in saturation decreases with increase in

a) gate voltage

b)drain voltage

c)source voltage

d)body voltage

Answer : b

Explanation:

At the edge of saturation i.e when drain to source voltage reaches VD sat the inversion layer charge at the drain end become zero(ideally). The channel is said to be pinched off at the drain end. If the drain to source voltage VDS is increased even further beyond the saturation edge so that VDS>VD sat