Chapter 23: Field Effect Transistors (FETs)
MULTIPLE CHOICE
1. In a JFET, the U- shaped region is called the ____ and is flush with the upper surface of the substrate.
a.
channel
c.
source
b.
gate
d.
drain
2. Because the gate-to-source voltage is reverse biased, the JFET has a(n) ____ input resistance.
a.
low
c.
high
b.
moderate
d.
extremely high
3. ____ are called depletion mode devices.
a.
P-channel JFETs
c.
N-channel JFETs
b.
P-type units with P channels
d.
N-type units with N channels
4. ____ are enhancement mode devices.
a.
N-channel JFETs
c.
P-type units with P channels
b.
N-type units with N channels
d.
P-channel JFETs
5. One difference between MOSFETs and JFETs is that the gate of the N-channel depletion MOSFET
can also be made ____ with respect to the source. This cannot be done with a JFET because it would
cause the gate and channel PN junction to be ____ biased.
a.
positive, forward
c.
negative, forward
b.
positive, reverse
d.
negative, reverse
6. In an N-channel depletion MOSFET, a large amount of drain current flows when the gate voltage is
equal to ____.
a.
negative one
c.
one
b.
zero
d.
infinity
7. In an N-channel depletion MOSFET, the drain-to–source voltage (EDS) must always be applied so that
the drain is ____ the source.
a.
negative with respect to
c.
positive with respect to
b.
equal to
d.
zero with respect to
8. ____ are devices that are normally off.
a.
P-channel enhancement MOSFETs
c.
N-channel JFETs
b.
N-channel depletion MOSFETs
d.
P-channel JFETs
9. In a P-channel enhancement MOSFET, when the gate is made negative with respect to the source,
____ are drawn toward the gate, where they gather to create a P-type channel that allows current to
flow from the drain to the source.
a.
cathodes
c.
electrons
b.
holes
d.
anodes
10. In testing MOSFETs with an ohmmeter, the meter should register a(n) ____ resistance in both the
forward- and reverse-resistance test between the gate and source or drain.
a.
negative
c.
positive
b.
zero
d.
infinite
COMPLETION
1. The ____________________ is a unipolar transistor that functions using only majority carriers.
2. In a JFET, the ____________________ is used to control the output current.
3. MOSFETs are usually ____________________, like JFETs.Therefore the source and drain can usually
be reversed or interchanged.
SHORT ANSWER
1. Describe the safety precautions that must be observed when handling and using MOSFETs.
ANS:
2. Describe the procedure for testing MOSFETs with an ohmmeter.