Two Marks Questions with Answers

Two Marks Questions with Answers

Q.1 W/iy is FET called a unipolar device ? AU : May-02

(Refer section 3.1)

Q.2 Hoie can a FET be used as a uoltage controlled resistor ? AU : May-02

(Refer section 3.1)

Q.3 What are the advantages of FETs ?

(Refer section 3.7)

AU : May-03, Dec.-13

Q.4 Mention the three regions that are present in the drain-source characteristics of JFET. AU : Dec.-04

(Refer section 3.4)

Q.5 What is pinch-off voltage in FET ?

(Refer section 3.3)

AU : May-05, Dec.-06, 07, 08, 09

Q.6 List the characteristics of JFET. AU : Dec.-05

(Refer section 3.4)

Q.7 Distinguish between BJT and FET. AU : May-06, 07, 08, 10, 12

(Refer section 3.7)

Q.8 Mention the disadvantages of FET compared to BJT.

Ans. : Disadvantages of FET compared to BJT are :

1. Relationship between input and output is non-linear; whereas in case of BJT it is linear.

2. Gain-bandwidth product is less in FET than BJT.

Q.9 Give the drain current equation of JFET.

(Refer section 3.4.2)

Q.10 List the JFET parameters.

Ans. : Transconductance g_m : It is the change in the drain current for given change in gate to source voltage with the drain to source voltage constant.

Q.11 List the special features of FET.

(Refer section 3.1)

Q.12 Define amplification factor in JFET.

(Refer Q. 10)

Q.13 Why thermal runaway is not there in FETs ?

Ans. : The FET has a positive temperature coefficient of resistivity. In FET, as temperature increases its drain resistance also increases, reducing the drain current. Thus, unlike BJT, thermal runaway does not occur with FET.

Q.14 Draw two different circuits that bias a JFET amplifier.

(Refer section 3.5)

Q.15 Explain one application of JFET used as variable resistor.

(Refer section 3.6)

Q.16 List the different types of FET biasing circuits.

Ans : Different types of FET biasing circuits are : 1. Fixed bias 2. Voltage divider bias 3. Self bias

Q.17. Draw the small signal equivalent circuit of FET.

(Refer section 3.11.2)

Q.18 Draw the small signal model of a Junction Field Effect Transistor and write down the equation which helps in deriving the equivalent circuit.        

(Refer section 3.11.2)

Q.19 Write any two points of comparison between JFET with BJT.

(Refer section 3.7)

Q.20 Draw the small signal equivalent circuit of a CS JFET.

(Refer Fig. 3.8.3)

Q.21 Draw the transfer and drain characteristics curves of JFET. (Refer sections 3.4.1 and 3.4.2) AU: May-16

Q.22 State the advantages of FET over BJT. [Section 3.8]

AU: Dec.-17

Q.23 Give any two differences between JFET and BJT. [Section 3.8]

AU : Dec.-18