We are Apogeeweb Semiconductor Electronic

WELCOME TO OUR BLOG

Home arrow Semiconductor Information arrow N Channel vs P Channel MOSFET

arrow left

arrow right

N Channel vs P Channel MOSFET

Author: Apogeeweb
Date: 26 Aug 2022
 871
p-channel mosfet

Catalog

Introduction

Ⅰ Construction of a MOSFET

ⅡSymbols for MOSFETs

Ⅲ N Channel MOSFET vs P Channel MOSFET

Ⅳ Differences Between an N-Channel and a P-Channel MOSFET

Ⅴ Why Prefer an N-Channel MOSFET to a P-Channel MOSFET?

Ⅵ Advantages of MOSFET

Ⅶ Disadvantages of MOSFET

Ⅷ Applications of MOSFET

Introduction

Since the mid-1980s, MOSFETs have been the preferred transistor technology in the majority of Switched Mode Power Supplies (SMPS). MOSFETs are used as the primary switching transistor as well as to improve efficiency when used as gated rectifiers. This blog compares P Channel and N Channel enhancement mode MOSFETs to help you select the best switch for your power application.

 Construction of a MOSFET

A MOSFET's construction is similar to that of a FET. On the substrate to which the gate terminal is connected, an oxide layer is deposited. Because this oxide layer acts as an insulator (insulating from the substrate), the MOSFET is also known as an IGFET. A lightly doped substrate is diffused with a heavily doped region in the fabrication of MOSFETs. They are classified as P-type or N-type MOSFETs based on the substrate used.

The following figure shows the construction of a MOSFET.

construction-of-a-mosfet

The MOSFET's operation is controlled by the voltage at the gate. Because the gate is isolated from the channel, both positive and negative voltages can be applied to it. When the gate bias voltage is negative, it acts as a depletion MOSFET, and when the gate bias voltage is positive, it acts as an enhancement MOSFET.

Ⅱ Symbols for MOSFETs

symbols-for-n mosfets

symbols-for-p-mosfets

Gate (G), Source (S), and Drain (D) pins are present on all MOSFETs. The voltage between Gate and Source (Vgs) determines whether or not current flows through the Source and Drain. Each type has its logic for turning the MOSFET on or off. I'll go over it in detail in the following two chapters.

If a MOSFET is fully turned on with Vgs in the 3 to the 5-volt range, it is classified as a Logic Level MOSFET. All Logic Level MOSFETs should be fine if you use a 5V Arduino board. If you're using a 3.3V board, make sure the MOSFET you're using is compatible with 3.3V switching.

MOSFETs typically need Vgs to be 10V or more to be fully ON.

 N Channel MOSFET vs P Channel MOSFET

The source of an N-channel MOSFET is connected to the ground, the drain to the load and the FET turns on when a positive voltage is applied to the gate. N-channel MOSFETs are the most commonly used and easiest to work with. They are also less expensive to produce and thus available at lower prices with higher performance than p-channel MOSFETs.

In a P-channel MOSFET, the source is connected to a positive voltage, and the FET turns on when the voltage on the gate falls below a certain threshold (Vgs 0). This means that if you want to switch voltages higher than 5V with a P-channel MOSFET, you'll need another transistor (of some kind) to turn it on and off.

P-Channel MOSFET

A P- channel region is located between the source and drain terminals of a P- channel MOSFET. It is a four-terminal device with the following terminals: gate, drain, source, and body. The drain and source are p+ regions, and the body or substrate is n-type. Current flows in the direction of positively charged holes.

When a negative voltage with repulsive force is applied to the gate terminal, electrons present beneath the oxide layer are pushed downwards into the substrate. The depletion region is populated by bound positive charges associated with donor atoms. The negative gate voltage also attracts holes into the channel region from the p+ source and drain regions.

depletion-mode-p-channel

Depletion Mode P Channel

p-channel-enhanced-mode

P Channel Enhanced Mode

 Working

A p channel depletion MOSFET is simply the inverse of an n channel depletion MOSFET in terms of construction. The prebuild channel in this case is made of p-type impurities sandwiched between heavily doped p-type source and drain regions. When we apply a positive voltage to the gate terminal, electrostatic action attracts minority carriers, i.e. free electrons from the p-type region, resulting in the formation of static negative impurity ions. As a result, a depletion region forms in the channel, and the conductivity of the channel decreases. We can control the drain current by applying a positive voltage to the gate.

working

N- Channel MOSFET

The N-channel region of an N-Channel MOSFET is located between the source and drain terminals. It is a four-terminal device with the following terminals: gate, drain, source, and body. The drain and source of this type of Field Effect Transistor are heavily doped n+ regions, while the substrate or body is P-type.

The flow of current in this type of MOSFET is caused by negatively charged electrons. When a positive voltage with repulsive force is applied to the gate terminal, the holes beneath the oxide layer are pushed downward into the substrate. The bound negative charges associated with the acceptor atoms populate the depletion region.

The channel is formed when electrons reach it. The positive voltage also attracts electrons into the channel from the n+ source and drain regions. When a voltage is applied between the drain and the source, current flows freely between them, and the gate voltage controls the electrons in the channel. If we apply negative voltage instead of positive voltage, a hole channel will form beneath the oxide layer.

enhancement-mode-n-channel

Enhancement Mode N Channel

symbols-for-n-channel-depletion-and-enhancement-types

Symbols for N-channel Depletion and Enhancement Types

 Working

The n-channel MOSFET operates on the assumption that the majority of the carriers are electrons. The movement of electrons in the channel is responsible for the current flow in the transistor. The formation of the gate terminals requires the use of p-substrate material.

N-Channel Characteristics

No current flows through the transistor in n-channel enhancement mode until the voltage at the gate and terminal source exceeds the minimum voltage cut in value. When the voltage at the drain and the terminal source is applied, there is no visible current flow.

characteristic-of-n-channel-mosfet

Characteristic of N-Channel MOSFET

Ⅳ Differences Between an N-Channel and a P-Channel MOSFET

The primary distinction between an N-Channel and a P-Channel MOSFET is that the N-Channel is usually connected to the Ground (-) side of the load (the device being powered), while the P-Channel is connected to the VCC (+) side.

n-channel-mosfet

p-channel-mosfet

Why must you link one to the negative and the other to the positive?

Enhancement-Type ("Normally OFF") An N-Channel MOSFET turns on when there is a sufficiently high positive voltage on the Gate relative to the Source (typically 3 to 5 volts for Logic Level MOSFETs). You can use VCC (+) to activate it by connecting the Source to the Ground (-).

n-channel-mosfet-on-gnd-side

 

If you connect your N-Channel MOSFET to the VCC side of the load, the Source value will also be very close to VCC. To activate the MOSFET, you must apply a voltage greater than VCC to the Gate. Because this higher voltage is not always readily available, connecting the Source to the Ground makes more sense.

 n-channel-mosfet-on-vcc-side

Enhancement-Type ("Normally OFF") A P-Channel MOSFET is similar to an N-Channel MOSFET turned upside down. It activates if the Gate has a sufficiently high negative voltage relative to the Source. You can activate it by connecting the Source to the VCC (+) and the Ground (-).

p-channel-mosfet-on-vcc-side

 

Connecting a P-Channel MOSFET to the negative side of the load has the same issue as connecting an N-Channel MOSFET. Except that the Source would be too close to the Ground this time. To activate the Gate, you must apply a negative voltage (relative to the Ground).

p-channel=mosfet-on-ground-side

It's simple: connect the Source pin of an N-Channel MOSFET to the negative output of your power supply, and the Source pin of a P-Channel MOSFET to the positive output of your power supply.

 Why Prefer an N-Channel MOSFET to a P-Channel MOSFET?

You could design your circuit in such a way that you could use either of them. It doesn't matter if you have an Arduino that runs on 5V and the device you're turning on also runs on 5V. As long as you wire it correctly, you could use an N-Channel or P-Channel MOSFET.

So, why is N-Channel preferred over P-Channel?

With an N-Channel MOSFET, you can create a common ground between the 12V power source and your Arduino.

When using a P-Channel MOSFET, you must create a Common VCC rather than a Common Ground. However, having a Common Ground between connected devices and modules is standard practice.

You can power your Arduino with the same 12V power source that you are switching with an N-Channel MOSFET.

The barrel connector's negative input connects directly to Arduino Ground. When using an N-Channel MOSFET as a power switch, this is not an issue. In any case, the Grounds are linked. Because the 5V power input must be pulled up to the positive output of the power supply, you cannot connect the negative output of the power supply to the Arduino Ground with a P-Channel MOSFET. You can send 12 volts through the Arduino by connecting the Grounds as well.

N-Channel MOSFETs outperform P-Channel MOSFETs in terms of efficiency.

It all boils down to physics. The charge carrier in N-Channel MOSFETs is electron flow. Hole flow, which has less mobility than electron flow, is used as the charge carrier in P-Channel MOSFETs. As a result, they are more resistant and less efficient. With higher loads, a P-Channel MOSFET will get hotter than an N-Channel MOSFET.

 Advantages of MOSFET

Few of the advantages are :

  • It produces increased efficiency even when operating at low voltage levels.
  • When there is no gate current, more input impedance is created, which increases the device's switching speed.
  • These devices can operate at low power levels and draw little current.

 Disadvantages of MOSFET

Few of the disadvantages are :

  • When these devices are operated at overvoltage levels, the device becomes unstable.
  • Because the devices have a thin oxide layer, electrostatic charges may cause damage to the device.

 Applications of MOSFET

The applications of MOSFET are

  • MOSFET amplifiers are widely used in a wide range of frequency applications.
  • These devices provide the regulation for DC motors.
  • Because of their increased switching speeds, these are ideal for the construction of chopper amplifiers.
  • Serves as a passive component for a variety of electronic elements.

Best Sales of diode

Photo Part Company Description Pricing (USD)

Alternative Models

Part Compare Manufacturers Category Description

Ordering & Quality

Image Mfr. Part # Company Description Package PDF Qty Pricing (USD)

Related Articles

pinglun

Leave a Reply

Your email address will not be published.

 
 
   
 
code image
Rating: poor fair good very good excellent

# 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z