UNIT-4

JUNCTION FIELD EFFECT TRANSISTOR (FET)

SYLLABUS
Construction, Principle of operation, Pinch-Off Voltage, Volt-Ampere characteristic,
Comparison of BJT and FET, FET as Voltage Variable Resistor, MOSFET, MOSFET as a
capacitor.

COURSE OUTCOME
By the end of this chapter, students will be able to analyze the concepts of FETs and
MOSFETs.
 FIELD EFFECT TRANSISTOR (FET) (Example Q: What is FET?
What are the types of FET?)

 The Field Effect Transistor, FET, is a three-terminal active device that uses an electric
field to control the current flow.
 It has a high input impedance which is useful in many circuits.
 FETs are unipolar devices, which means they use only one type of charge carrier
(electrons or holes) to control the current flow, unlike BJT in which current is because
of two types of charge carriers.

TYPES OF FET

COMPARISON OF BJT & FET (Example Q: Compare BJT and FET)

Parameter BJT FET

Output depends on the input Output depends on the input voltage

Control method current (IB or IE) so it is called a (VGS) so it is called a Voltage
Current Controlled Device. Controlled device.

Names of the Terminals Emitter, Base, and Collector Drain, Source, and Gate
Common Base, Common Emitter
Common Source, Common Drain,
Configurations & Common Collector
Common Gate configurations.
configurations
Bias type of input Forward bias in base (B) and Reverse bias in the source (S) and gate
circuit at active mode emitter (E) junction (G) junction
Symbols

Noise level Highly noisy Less Noisy

Current Contribution Transistor current depends on both Transistor current depends only on the
majority and minority carriers majority carriers.

Name Bipolar device Unipolar device

The minority carriers injected
Dependence on Controlling with depletion region
across the forward voltage in the
transistor work width in the channel by reverse bias
junction
Current moves between emitter and Current moves between source and
Current on parts
base and collector (3 parts) drain (2 parts)
Input resistance Lower due to forward bias Higher due to reverse bias

Thermal stability Less Best

JFET (Junction Field Effect Transistor) (Example Q: Explain the

construction and working of an N-Channel JFET with the help of its
characteristics.)

Junction Field Effect transistor is of two types

1. N-Channel JFET
2. P-Channel JFET

CONSTRUCTION OF N-CHANNEL JFET

 The structure of n-channel JFET consists of n-type substrate the two sides of which are
diffused with p-type material.
 The n-region is called the Channel as it forms a path between the Source and the Drain.
 The two p-regions are electrically connected and the common terminal is called Gate.
 WORKING:

 The fundamental operation of UJT depends on how the PN junction is biased.

 When the junction is reverse biased the width of the channel and thus the current flow
between Drain and Source is controlled.
 As seen the PN junction plays a key role in the operation of the device and hence the
name Junction Field - Effect Transistor (JFET).

Case-1: (VGS = 0 V; VDS is positive (> 0V))

 Let the voltage applied to the Gate terminal be 0 V i.e., VGS= 0 V, and the voltage VDS is
positive with a polarity as shown in the Figure.
 Under these bias conditions there is a flow of current IDS from Drain to Source the
magnitude of which depends on the VDS voltage.

 As VDS is applied, the electrons move toward the Drain terminal, and the Drain
Current (IDS) starts flowing.
 The Drain Current IDS is limited only by the n-channel resistance present in between
the Drain and Source.
 As the Drain-Source voltage VDS increases from 0V to a few volts, the Drain
current IDS will also increase as per Ohm's law as the channel resistance is constant.
 This region of operation is called the Ohmic region or more popularly as Triode
region.
 As we further increase the voltage VDS it approaches a voltage level called Vp (pinch
off), the depletion region widens, and channel width reduces.
 This results in the reduction of the conduction path i.e., the resistance of the channel
increases.

Depletion Region width increases and Channel width reduces when VDS is increased

 As we further increase the voltage V DS, the two depletion regions touch each other as
shown in Figure below and the n-channel JFET is said to be pinched - off and the
value of VDS equals VP.
 As the value of the voltage VDS is further increased beyond the pinch-off voltage V P,
the two depletion regions that touch each other move across the length of the channel.
 Depletion Regions touch each other as VDS is further increased

 The Drain current levels off and remains constant (almost) with further increase in
the voltage VDS.
 The value of this drain current IDS is called IDSS and it is the maximum current for a
given n-channel JFET. The device is said to be operating in the saturation region.
 The n-channel JFET under these conditions where VDS > VP acts like a current
source generating a constant current of IDSS.
 It may be noted here that the maximum Drain current IDSS for a JFET is defined for
VGS = 0 V and VDS > VP.

IDSS current becoming constant (saturation region) after VP voltage

 IDS versus VDS graph for different values of VGS

The following points can be noted from the above characteristics

 In the Ohmic region the n-channel FET acts as a Voltage Controlled Resistor i.e., the
resistance of the device in this region of operation is controlled by the voltage applied
at the Gate terminal VGS.
 Sometimes the Ohmic region may also be called a Voltage Controlled Resistance
Region.
 The slope of the curve which indicates the resistance of the device between Drain and
Source for VDS = VP is a function of VGS.

Case-2: (VGS < 0)

 When VGS is negative (gate connected to the negative terminal of the battery), the width
of the depletion region of the gate channel increases.
 This effectively reduces the area of the channel and increases the channel resistance by
reducing the charge flow through the channel.
 As channel area decreases the drain current ID decreases for a given VDS. JFET is
operating like a resistance whose value is controlled by the Gate-to-Source voltage VGS.
 As the value of VGS is made more and more negative, the depletion region width
increases and it occupies the entire channel.
 This will result in the channel being completely depleted of charge carriers (electrons)
in an n-channel JFET. This situation may be considered as the effective disappearance
of the channel.
 As VGS is made sufficiently negative and reaches the value -V P,(negative Pinch-off
voltage) then the drain current almost becomes 0 mA and the device is said to be turned
OFF.
Transfer Characteristics:

 As we understood that the drain current IDS depends on the drain voltage VDS and the gate
voltage VGS, thus
IDS = f (VDS, VGS)
 Transfer characteristics show a relation between the gate voltage VGS and the drain
current IDS and are plotted by keeping VDS constant.

 The curve is plotted by varying the value of VGS and finding the value of the ID.
 As in the case of an N-channel JFET, a negative voltage on the gate terminal decreases
the channel and thus decreases the drain current IDS current
 As the voltage VGS is increased beyond pinch-off voltage (VP) the drain current increases
till it becomes equal to IDSS at VGS = 0 V. (VGS (OFF))
 Equation for drain current under this condition can be given as
𝑰 ≅ 𝑰[𝟏 − 𝑽𝑮𝑺
]
�

𝑽
𝑫𝑺 𝑫𝑺
�

𝑺 𝑮𝑺(𝑶𝑭𝑭)
Where IDSS is the maximum drain to source current that results when VGS = 0 V and VDS >
VP (pinch-off voltage).
VGS (OFF) is the negative pinch-off voltage (as shown in the above graph) and the value of
VGS (OFF) is equal to | VP| in the above equation. i.e., VGS(OFF) = |VP|

FET PARAMETERS (Example Q: Discuss the various parameters

of FET and obtain a relation between them.)

1. Transconductance or Mutual Conductance (gm):

Defined as the ratio of output current IDS to the input voltage VGS when the output voltage

𝑰𝑫𝑺
VDS is maintained constant. Transconductance is measured in mhos.

𝒈𝒎 = 𝑮𝑺| ℧
𝑽 𝑽𝑫𝑺 𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕
 2. Drain Resistance (rd):
The ratio of output voltage VDS to the output current IDS maintaining the input voltage

𝑽𝑫𝑺
VGS constant is known as drain resistance rd. It is measured in ohms.

𝒓𝒅 = | Ω
𝑰
𝑫 𝑽𝑮𝑺 𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕
𝑺
3. Amplification factor (µ):
The amplification factor is the ratio of the output voltage VDS to the input voltage VGS

𝑽𝑫𝑺
when the output current IDS is maintained constant.

𝝁 | 𝑵𝒐 𝒖𝒏𝒊𝒕𝒔
= 𝑽 𝑮𝑺 𝑰𝑫𝑺
𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕
Relation between 𝝁, 𝒈𝒎 𝒂𝒏𝒅
𝒓𝒅
As we know that the output current in a FET is a function of output voltage VDS and input
voltage VGS, we can write

IDS = f (VDS, VGS)

the amplification factor 𝝁 = = ×

Also, 𝑽𝑫𝑺 𝑽𝑫𝑺 𝑰𝑫𝑺

𝑽𝑮𝑺 𝑽𝑮𝑺 𝑰𝑫𝑺

𝝁= ×
Thus 𝑽𝑫𝑺 𝑰𝑫𝑺

𝑰𝑫𝑺 𝑽𝑮𝑺

As 𝑽𝑫𝑺 = 𝒓
𝑰𝑫𝑺 𝑰𝑫𝑺
=
𝒈
and
�
�
𝑽𝑮𝑺
�

∴ 𝝁 = 𝒈 𝒎 × 𝒓𝒅
�

Applications of JFET: (Example Q: Mention the applications,

advantages and disadvantages of JFET)

Some applications of JFET are listed below:

 JFET is used as a switch

 JFET is used as a chopper
 JFET is used as a buffer
 JFETs are used in oscillatory circuits
 JFETs are used in cascade amplifiers

Advantages of JFET
Some advantages of JFET are listed below:

 JFET has a high impedance

.
  JFET can be fabricated in a smaller size, and as a result, they occupy less space in
circuits due to their smaller size.

 JFETs are low power consumption devices

Disadvantages of JFET

Some disadvantages of JFETs are as follows:

 It has a low gain-bandwidth product

 The performance of JFET is affected as frequency increases due to feedback by
internal capacitance

METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR (MOSFET)

(Example Q: What is a MOSFET? What are the different types of
MOSFETs?)

MOSFET is also known as Insulated Gate Field Effect Transistor (IGFET). It is basically
of two types.
1. Enhancement MOSFET
2. Depletion MOSFET

ENHANCEMENT MOSFET:
 The channel between the source and drain terminals is not physically present in an
Enhancement MOSFET, thus in the absence of gate voltage VGS no drain current will
flow through the FET.
 When sufficient gate voltage VGS is applied, the channel will be enhanced (and thus the
name) between source and drain semiconductors, and current will flow in the FET.
Enhancement MOS is of two types
1. N-Channel
2. P-Channel
N-Channel Enhancement MOSFET: (Example Q: Explain the construction and
working of N-channel Enhancement MOSFET.)

CONSTRUCTION:

 To construct an N-Channel Enhancement MOSFET first a lightly doped P-type

semiconductor is considered.
 This semiconductor forms the base for the transistor and so it is called a substrate.
 Two heavily doped N-type semiconductors are now introduced into the lightly doped
substrate.
 Now a thin layer of Sio2 is developed on the top of the substrate. Holes are etched into
the sio2 layer to make ohmic contacts with the N-type semiconductors.
 These ohmic contacts are referred to as Source and Drain terminals.
 Aluminium metal is deposited on the top of this glass layer and the Gate terminal is
taken from it.
 Thus, MOSFET is considered to be a four-terminal device with the fourth terminal
taken out of the substrate.
WORKING OF N-CHANNEL ENHANCEMENT MOSFET:
 The working of MOSFET is similar to that of JFET where a battery is connected
between the Source terminal and Drain terminal with the negative terminal connected to
the Source and the positive terminal connected to the Drain.
 This VDS voltage source will generate the Drain to Source current (IDS) only when the
Source and Drain semiconductors(N-type) are connected by an N-type channel.
 N-channel can be enhanced between the Source and Drain semiconductors by a positive
voltage (VGS > 0V) applied on the Gate terminal.
 The positive potential applied on the Gate (metal) terminal when increased, will be able
to draw the electrons present in the substrate to its surface as the Sio2 layer acts as a
dielectric allowing charge inversion between the Gate (metal) and the Substrate
(semiconductor).
 These electrons will accumulate between the Source and Drain semiconductors forming
an N-type channel that connects the Source and Drain.
 The value of VGS (> 0V) voltage at which the N-channel is created between the two N-
type semiconductors is known as threshold Voltage VT.
 Thus, when VGS > VT and when VDS > 0V, drain current IDS will flow through the
transistor.

 When VDS is further increased, a reverse bias is formed at the PN junction near the
Drain terminal resulting in a thick depletion region near the PN junction.
 Due to the increased depletion region the drain current will face more resistance near
the drain terminal that will force it to become constant and not increase further .

 This situation is called the pinch-off situation and the drain current is called the
saturation current IDS(SAT)
  The voltage at which we get the saturation current is called saturation voltage VDS(SAT).
We can thus conclude, that pinch-off is reached when VGS > 0 (constant) and VDS =
VDS(SAT), ID = ID(SAT).

 From the graph, it is clear that the current IDS will become constant at a specific value of
VDS. current IDS increases only when the value of VGS is increased.

DEPLETION MOSFET: (Example Q: Explain the construction and working

of Depletion MOSFET.)

 N-Channel Depletion MOSFET is a 3-terminal device similar to an N-Channel

Enhancement MOSFET.
 The only difference between the Enhancement and Depletion MOSFETs is the existence
of an N-channel.
 In an N-channel Depletion MOSFET, N-channel is already present where as in an N-
Channel enhancement MOSFET Channel is not physically present.
Depletion MOSFET is of two types
1. N-Channel
2. P-Channel

N-Channel Depletion MOSFET

CONSTRUCTION

 To construct an N-Channel Depletion MOSFET, a lightly doped P-type substrate is

considered into which two heavily doped N-type semiconductors are introduced.
 Source and Drain terminals are derived from these heavily doped N-type semiconductors
 Now moderately to lightly doped N-type impurities are diffused into the substrate
between the two heavily doped N-type semiconductors. This region acts as the channel
and connects both the Source and Drain semiconductors.
 A thin layer of SiO2 is developed on the top of the substrate and aluminium metal is
deposited on the top of it. Gate terminal is taken from the metal layer.
 Thus, the Depletion MOSFET has three terminals Source, Drain and Gate.

WORKING OF N-CHANNEL DEPLETION

MOSFET Case-1(VGS = 0V):

  When Gate terminal is connected to ground (VGS = 0V) and VDS is maintained positive,
drain current IDS flows from Drain to Source.
 With increase in VDS, IDS increases to a certain level until it becomes constant/saturated
(IDSS) at a particular value of VDS.

Case-2 (VGS < 0V):

 When negative potential is applied on the Gate terminal, holes of the P-type substrate
will be attracted towards the negative Gate terminal and recombine with electrons in the
N channel.
 The (N)channel is thus depleted of negative charge carriers and drain current IDS will
decrease till it falls to zero value at a value of VGS voltage called pinch-off voltage.

Case-3 (VGS > 0V):

 With VGS > 0, the minority carriers of the p-type substrate, i.e., electrons, will get
attracted towards the gate terminal, thereby increasing the concentration of electrons in
the N- channel.
 As a result, the drain current IDS will increase and exceed the saturation current (IDSS).
Thus, we can say that, when VGS > 0 and VDS > 0, ID > IDSS.
 The graph shows that the current IDS will flow for both positive and negative values of
VGS.
 It can be observed that the drain current is less than the saturation current for the
negative value of gate voltage (VGS < 0V), whereas for the positive value of gate
voltage (VGS > 0V), the drain current exceeds the saturation current.
 VGS = VP is also represented in this graph for which drain current is zero irrespective of
drain to source voltage (VDS).
 V-I Characteristics of Depletion MOSFET
Differences between Enhancement MOSFET and Depletion MOSFET:
S. No. Depletion MOSFET Enhancement MOSFET
The type of MOSFET where the
The type of the MOSFET where the
channel depletes with the gate voltage
1 channel is enhanced or induced using the
is known as depletion or simply D-
gate voltage is known as E-MOSFET.
MOSFET.
The channel is fabricated during There is no channel during its
2
manufacturing. manufacturing.
It conducts current between its source
It does not conduct current when there is
3 and drains when there is no Gate
voltage VGS. no Gate voltage VGS.
Applying reverse voltage to the gate Applying reverse voltage does not
4
reduces the channel width. affect E-MOSFET since there is no
channel.
Applying forward voltage to the gate Applying the forward voltage generates
5
increases the channel width. and increases the width of the channel.
It can work in both depletion and
6 It can only work in enhancement mode.
enhancement mode.
7 It is a normally ON transistor. It is a normally OFF transistor.
It switches OFF with reverse biasing It switches ON with the forward biasing
8
of gate. of the gate.
There is no threshold voltage for There a threshold voltage at which the
9
switching ON the MOSFET. MOSFET switches ON.
Diffusion or subthreshold current does E-MOSFET has sub-threshold current
10
not exist. leakage between its source and drain.

MOSFET AS A CAPACITOR (Example Q: Explain the capacitance exhibited

by a MOSFET.)

 In a MOSFET the Gate and the Channel are separated by a thin layer of SiO2, they
form a capacitance that varies along with gate voltage.
 MOSFET acts as a MOS capacitor and it is controlled by the input Gate to
Source voltage.
  So, it will act like a voltage-controlled variable capacitor.
 Hence MOSFET can be used as a voltage-controlled capacitor.

Differences between JFET and MOSFET:

Parameter JFET MOSFET
JFET stands for Junction MOSFET stands for Metal Oxide
Full form
Field Effect Transistor. Semiconductor Field Effect Transistor.
JFET is a three-terminal MOSFET is also a four-terminal device,
device, where the terminals where the terminals are – Source (S),
Terminals
are named – Source (S), Drain (D), Gate (G) and Body or
Drain (D) and Gate (G). Substrate (B).
Mode of JFET operates only in MOSFET can be operated in both
operation depletion mode. enhancement mode and depletion mode.
JFET has a gate terminal
The gate terminal of the MOSFET is
Gate terminal which is not insulated from
insulated from thin layer of metal-oxide.
the channel.
MOSFET has a continuous channel only
JFET has a continuous in depilation type, but not in the
Channel channel. The channel exists enhancement type. Thus, the channel
permanently. exists permanently in depletion type, but
not in enhancement type.
MOSFETs are of four types: P-channel
JFETs are of two types: N- enhancement MOSFET, P-channel
Types channel JFET and P-channel depletion MOSFET, N-channel
JFET. enhancement MOSFET and N-channel
depletion MOSFET.
JFET has a high input
Input MOSFET has very high input impedance
impedance which is of the
impedance of the order of 1014 Ω
order of 109 Ω.
JFET is less susceptible to MOSFET is more susceptible to damage
Susceptible to
damage as it has high input because the presence of metal oxide
damage
capacitance. reduces input capacitance.
The manufacturing process
Manufacturing
of JFET is simple and less Manufacturing of MOSFET is complex.
process
sophisticated.
 The drain resistance of
Drain The drain resistance of MOSFET is low
JFET is high and ranges
resistance of the order of 1 Ω to 50 Ω.
from 105 Ω to 106 Ω.
The addition of metal oxide increases the
Manufacturing The manufacturing cost of a
manufacturing cost of MOSFET. Thus,
cost JFET is less than MOSFET.
MOSFET is expensive than JFET.
For JFET, gate current is
Gate current For JFET, gate current is more.
more.
Characteristics JFET has more flat MOSFET has relatively less-flat
curve characteristics curve. characteristics curve.
In JFET, the conductivity of
In MOSFET, the conductivity is
Conductivity the device is controlled by
controlled by the charge carriers induced
control the reverse biasing of the
in the channel.
gate.
Signal handling The signal capacity of the MOSFET has more signal handling
capacity JFET is less. capacity than JFET.
JFET is mainly used in low MOSFET is extensively used in high
Applications
noise applications. noise applications.

Applications of MOSFET: (Example Q: Discuss the applications of MOSFET)

1. Switching operation:
 One of the most common applications of MOSFETs is as switches in power electronics
circuits.
 A MOSFET can switch on and off very fast, which allows it to handle high frequencies
and reduce power losses.
 A MOSFET can also handle high currents and voltages, which makes it suitable for high-
power applications.

2. Amplifying Application:
 Radio-frequency amplifiers: These are circuits that amplify signals in the radio-frequency
range, such as radio waves or microwaves. A MOSFET can operate at high frequencies
due to its fast-switching speed.
 Audio amplifiers: These are circuits that amplify signals in the audio-frequency range,
such as sound waves or music. A MOSFET can operate with low distortion and noise due
to its high input impedance and low output impedance.
 Sensor amplifiers: These are circuits that amplify signals from sensors, such as
temperature, pressure, light, or motion sensors . A MOSFET can operate with low power
consumption and high reliability due to its simple structure and robustness.

3. Other Applications:
 Choppers: These are circuits that chop or modulate a DC voltage into an AC voltage with
variable frequency and amplitude. A MOSFET can be used as a chopper to control the
duty cycle of a square wave applied to a transformer or an LC circuit, which changes its
output characteristics.
  Linear voltage regulators: A depletion-mode MOSFET can be used as a linear voltage
regulator to act as a variable resistor in series with the load, which adjusts its resistance
according to the load current.
 Digital circuits: A MOSFET can be used as a digital circuit element to implement logic
functions by using its switching behaviour.
 Microprocessors: A microprocessor consists of millions of transistors arranged in
complex architectures that execute various tasks. A MOSFET is one of the main types of
transistors used in microprocessors due to its high density, low power consumption, and
fast speed.

TOPIC BEYOND SYLLABUS

CMOS:

 CMOS stands for “Complementary metal Oxide Semiconductor”. It is also known as

“complimentary-symmetry metal Oxide Semiconductor COS-MOS”.
 It is widely used in the integration of chips (ICs). It is used in Computer memories
like RAM, ROM, EEPROM, cell phones, microprocessors and microcontrollers.

Structure of CMOS:

 The power dissipation and consumption are very less in CMOS and it is faster, so it is
widely used than the bipolar circuits.
 CMOS consists of P- channel MOSFET (PMOS) and N-channel MOSFET (NMOS)
developed in a single semiconductor substrate.

Structure of CMOS
Working of CMOS

 Both NMOS and PMOS together design the logic function.

  Same input voltage is used to turn ON one MOSFET and turn OFF other MOSFET.
 So, there is no need of pull up resistor in CMOS.
 NMOS is arranged in the pull-down network between the output and the ground.
 PMOS is arranged in the pull-up network.
 This pull-up and pull-down networks are arranged in such a way that when one
network is ON, the other network will be OFF.

Advantages of CMOS:
 Power consumption is less
 Large fan-out capability
 High noise immunity and noise margin
 Power dissipation is low
 Faster than NMOS

Disadvantages of CMOS:
 Manufacturing cost is high
 Propagation delay is higher than TTL and ECL

Applications of CMOS:
 Analog to digital converter
 Image sensors
 Amplifiers
 Static RAM
 Registers
 Microchip
 Microprocessors and microcontrollers
 Transceivers
 IMPORTANT QUESTIONS:

1. What is FET? What are the different types of FET?

2. Explain the construction and working of an N-channel JFET.
3. Explain how JFET acts as a Voltage Variable Resistor.
4. Discuss the applications of JFET.
5. Explain the transfer and drain characteristics of JFET.
6. What is a MOSFET? What are the different types of MOSFET?
7. With the help of neat diagrams explain the construction and working of an
Enhancement type MOSFET.
8. With the help of V-I characteristics briefly explain the construction and working of a
Depletion type MOSFET.
9. Bring out the differences between Enhancement type and Depletion type MOSFETS
and list the applications of MOSFET.
10. Compare JFET with MOSFET.
 OBJECTIVE QUESTIONS
1. FET is also called as a transistor [C]
A. Uni-junction B. Bipolar
C. Unipolar D. Tripolar

2. FET is a controlled device [B]

A. Current B. Voltage
C. Power D. Noise

3. A JFET has number of terminals [D]

A. 0 B. 1
C. 2 D. 3

4. is the region that connects Drain and Source semiconductors and through which
(drain) current flows through FET. [A]
A. Channel B. Gate
C. Drain D. Source

5. The terminals of FET are named as [B]

A. Source, Base, Gate B. Drain, Source, Gate
C. Drain, Emitter, Collector D. Gate Source, Collector

6. Other name of MOSFET is [C]

A. BJT B. JFET
C. IGFET D. Diode

7. The maximum Drain current (IDS) with gate voltage (VGS) zero is known as [A]
A. IDSS B. IGS
C. IGSS D. 0

8. In MOSFET, Channel is physically constructed at the time of fabricating the

transistor [D]
A. Enhancement B. Enhancement & Depletion
C. None D. Depletion

9. terminal is derived from metal in a MOSFET [B]

A. Source B. Gate
C. Drain D. Substrate

10. charge carriers contribute to current in FETs [A]

A. Majority B. Minority
C. Both majority & minority D. No charge carriers
 FILL IN THE BLANKS

1. MOSFET stands for Metal Oxide Semiconductor Field Effect Transistor.

2. Enhancement and Depletion are the two types of MOSFETs.

3. IGFET stands for Insulated Gate Field Effect Transistor.

4. The three terminals of FET are Gate, Drain, and Source.

5. Symbols of N-Channel and P-Channel JFET are

6. Ratio of Drain current IDS to Gate voltage VGS is called as mutual conductance (gm).

7. Amplification factor (µ) is the ratio of drain Voltage (VDS) to Gate voltage (VGS).

8. The value of VDS for which the Drain current (IDS) becomes constant when VGS = 0V is

known as Pinch-off voltage.

9. Drain resistance (rd) is the ratio of Drain Voltage (VDS) to the Drain current (IDS) in a

FET.

10. In an N-channel MOSFET the substrate is made of P-type semiconductor.