Deck 8: Field-Effect Transistors Fets

Question 1

Figure 4
Refer to Figure 4. The transistor is biased for

A)depletion mode
B)enhancement mode
C)neither

Answer 1

C

Question 2

A certain MOSFET has IDSS = 6 mA, VGS = -0.67 V, and VGS(off )= -5 V. The drain current, ID is

A)3.0 mA
B)0.75 mA
C)1.5 mA
D)4.5 Ma

Answer 2

D

Question 3

Figure 1
Refer to Figure 1, which represents two curves for a JFET. At ID = 6 mA, the transconductance, gm, is approximately

A)7700 µmho
B)3400 µmho
C)4300 µmho
D)12,000 µmho

Answer 3

B

Question 4

Figure 3 Assume I_DSS = 3.5 mA and V_GS(off)= -2 V.
Refer to Figure 3. An advantage to the voltage divider bias over self- bias is that voltage- divider bias

A)allows for greater variation in JFET parameters
B)has higher input resistance
C)enables the gate- source to be forward- biased or reverse- biased
D)all of the above

Question 5

Figure 3 Assume I_DSS = 3.5 mA and V_GS(off)= -2 V.
If a JFET bias circuit is designed with current- source biasing,

A)ID is constant for any JFET
B)IDSS is constant for any JFET
C)V_GS is constant for any JFET
D)V_GS(off)is constant for any JFET

Question 6

Figure 1
Refer to Figure 1. The source resistor, RS, that would self- bias this JFET at approximately VGS = -2 V is

A)220 ▲
B)470 ▲
C)360 ▲
D)1 M▲

Question 7

Figure 2 Assume the curve in (b)represents the transistor in (a).
Refer to Figure 2. If VS = 1.3 V, then VGS is

A)0 V
B)1.3 V
C)-1.3 V
D)4.0 V

Question 8

Figure 1
Refer to Figure 1. The curve on the left is called the

A)negative resistance curve
B)transconductance curve
C)transfer curve
D)characteristic curve

Question 9

An advantage of a JFET over a BJT is that the JFET has

A)higher input resistance
B)higher gain
C)better linearity
D)all of the above

Question 10

Figure 2 Assume the curve in (b)represents the transistor in (a).
Refer to Figure 2. IDSS is approximately

A)4.0 mA
B)6.0 mA
C)3.3 mA
D)8.0 mA

Question 11

The IGBT has characteristics of a

A)JFET input and BJT output
B)MOSFET input and a BJT output
C)BJT input and a JFET output
D)none of the above

Question 12

Figure 5 The equations for K and I_D are given in part (c).
Refer to Figure 5. ID is approximately

A)2.2 mA
B)0.88 mA
C)3.4 mA
D)1.2 mA

Question 13

Assume a transistor has an IDSS of 3.0 mA and a gm0 of 2500 µS. The gate- source cutoff voltage, ^VGS(off)^{, is}

A)-1.2 V
B)-1.8 V
C)-0.6 V
D)-2.4 V

Question 14

Figure 3 Assume I_DSS = 3.5 mA and V_GS(off)= -2 V.
Refer to Figure 3. If the drain voltage, VD, is 7.6 V, what is VGS?

A)-0.62 V
B)-1.8 V
C)-1.5 V
D)-4.2 V

Question 15

Figure 5 The equations for K and I_D are given in part (c).
Refer to Figure 5. VGS is

A)6.9 V
B)4.4 V
C)7.6 V
D)3.6 V

Question 16

A FET that has no channel until one is induced electrically is

A)an E- MOSFET
B)a VMOSFET
C)a p- channel JFET
D)a D- MOSFET

Question 17

Figure 3 Assume I_DSS = 3.5 mA and V_GS(off)= -2 V.
Refer to Figure 3. If RS were shorted to ground, the current, ID, is

A)1/2 IDSS
B)0 mA
C)> IDSS
D)IDSS

Question 18

Figure 1
Refer to Figure 1. The pinch- off voltage, Vp, is

A)-2.5 V
B)+5 V
C)-5 V
D)0 V

Question 19

A JFET that is operating as a voltage- controlled resistance is

A)typically biased near the origin
B)has minimum resistance at VGS = 0
C)is operating in the ohmic region
D)all of the above

Question 20

An E- MOSFET cannot use

A)drain- feedback bias
B)voltage- divider bias
C)self- bias

Question 21

The transconductance curve has the same shape as the transfer curve.

Question 22

Figure 5 The equations for K and I_D are given in part (c).
Refer to Figure 5. The transistor shown is a

A)p- channel E- MOSFET
B)p- channel D- MOSFET
C)n- channel D- MOSFET
D)n- channel E- MOSFET

Question 23

Figure 2 Assume the curve in (b)represents the transistor in (a).
Refer to Figure 2. A source resistor, RS, that will provide approximately ID = 4 mA is

A)250 W
B)560 ▲
C)470 ▲
D)330 ▲

Question 24

JFETs and MOSFETs are often referred to as square- law devices.

Question 25

The maximum drain current in a JFET is IDSS, which occurs at VGS = 0 V.

Question 26

Dual- gate MOSFETs can be either depletion or enhancement devices.

Question 27

All MOSFETs are subject to damage from electrostatic discharge.

Question 28

An n- channel E- MOSFET

A)can use either a positive or a negative gate voltage to conduct
B)requires a negative gate voltage to conduct
C)can have an open gate and still conduct
D)requires a positive gate voltage to conduct

Question 29

The most important application for an IGBT is in

A)high frequency amplifiers
B)logic circuits
C)high voltage and high current switching
D)power linear amplifiers

Question 30

For normal operation, the gate- source junction of a JFET is reverse- biased.

Question 31

The input structure of a MOSFET is a reverse- biased diode.

Question 32

Figure 2 Assume the curve in (b)represents the transistor in (a).
Refer to Figure 2. Assume that the source terminal is grounded. For this transistor, the drain voltage, VD, will be approximately

A)4.0 V
B)0 V
C)12 V
D)8.0 V

Question 33

Assume an n- channel JFET has a VGS(off)of -8 V. If VGS = -4 V, ID will be

A)IDSS
B)1/4 IDSS
C)1/2 IDSS
D)3/4 IDSS