P-Channel MOSFET Basics (2024)

P-Channel MOSFET Basics (1)

A P-Channel MOSFET is a type of MOSFET in which the channel of the MOSFET is composed of a majority of holes as current carriers. When the MOSFET is activated and is on, the majority of the current flowing are holes moving through the channels.

This is in contrast to the other type of MOSFET, which are N-Channel MOSFETs, in which the majority ofcurrent carriers are electrons.

Before, we go over the construction of P-Channel MOSFETs, we must go over the 2 types that exist. There are 2 types of P-Channel MOSFETs, enhancement-type MOSFETs and depletion-type MOSFETs.

A depletion-type MOSFET is normally on (maximum current flows from source to drain) when no differencein voltage exists between the gate and source terminals. However, if a voltage is applied to its gate lead, the drain-source channel becomes more resistive, until the gate voltage is so high, the transistor completely shuts off. An enhancement-type MOSFET is the opposite. It is normally off when the gate-source voltage is 0V(VGS=0). However, if a voltage is applied to its gate lead, the drain-source channel becomesless resistive.

In this article, we will go over how both P-Channel enhancement-type and depletion-type MOSFETs are constructed and operate.

How P-Channel MOSFETs Are Constructed Internally

P-Channel MOSFET Basics (2)

An P-Channel MOSFET is made up of a P channel, which is a channel composed of a majority of hole current carriers. The gate terminals are made up of N-type material.

Depending on the voltage quantity and type (negative or positive)determines how the transistor operates and whether it turns on or off.

How a P-Channel Enhancement-type MOSFET Works

P-Channel MOSFET Basics (3)

How to Turn on a P-Channel Enhancement Type MOSFET

To turn on a P-Channel Enhancement-type MOSFET, apply a positive voltage VS to the source of the MOSFET and apply a negative voltage to the gate terminal of the MOSFET (the gate must be sufficiently more negative than the threshold voltage across the drain-source region(VGDS). This will allow a current to flow through the source-drain channel.

So with a sufficient positive voltage, VS, to the source and load, and sufficient negative voltage applied to the gate, the P-Channel Enhancement-type MOSFET is fully functional and is in the active 'ON' mode of operation.

How to Turn Off a P-Channel Enhancement Type MOSFET

To turn off a P-channel enhancement type MOSFET, there are 2 steps you can take. You can either cut off the bias positive voltage, VS, that powers the source. Or you can turn off the negative voltagegoing to the gate of the transistor.

How a P-Channel Depletion-type MOSFET Works

P-Channel MOSFET Basics (4)

How to Turn on a P-Channel Depletion Type MOSFET

To turn on a P-Channel Depletion-Type MOSFET, for maximum operation, the gate voltage feeding the gate terminal should be 0V. With the gate voltage being 0V, the drain current is at is largest value and the transistor is in the active 'ON'region of conduction.

So, again, to turn on a P channel depletion-type MOSFET, positive voltage is applied to the source of the p-channel MOSFET. So we power the source terminal of the MOSFET with VS, a positive voltage supply. With a sufficient positive voltage, VS, and no voltage (0V) applied to the base, the P-channel Depletion-type MOSFET is in maximum operation and has the largest current.

How to Turn Off a P-Channel Depletion Type MOSFET

To turn off a P-channel MOSFET, there are 2 steps you can take. You can either cut off the bias positivevoltage, VDD, that powers the drain. Or you can apply a negative voltage to the gate. When a negativevoltage is applied to the gate, the current is reduced. As the gate voltage, VG, becomes more negative, the current lessens until cutoff, which is when then MOSFET is in the 'OFF' condition. This stops a large source-drain current.

So ,again, as negative voltage is applied to the gate terminal of the P channel depletion-type MOSFET, the MOSFET conducts less and less current across the source-drain terminal. When the gate voltage reaches a certain negative voltage threshold, it shuts the transistor off. Negative voltage shuts the transistor off. This is for a depletion-type P-channel MOSFET.

MOSFET transistors are used for both switching and amplifying applications. MOSFETs are perhaps the most popular transistors used today. Their high input impedance makes them draw very little input current, they are easy to make, can be made very small, and consume very little power.

Related Resources

How to Build a P-Channel MOSFET Switch Circuit

N-Channel MOSFET Basics

N Channel JFET Basics

P Channel JFET Basics

Types of Transistors

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P-Channel MOSFET Basics (2024)


What is basic P-channel MOSFET? ›

P-channel MOSFET

This is a MOSFET in the “ON state”. The channel is P-type, so this is called a P-channel MOSFET. Because the current in P-type semiconductors is carried by “holes”, it is more difficult for current to flow in P-type semiconductors than in N-type semiconductors where current is carried by “electrons”.

Why not use p-channel MOSFET? ›

P-Channel MOSFETs use hole flow as the charge carrier, which has less mobility than electron flow. And therefore, they have higher resistance and are less efficient. In other words, a P-Channel MOSFET will get hotter than an N-Channel MOSFET with higher loads.

How to control p-channel MOSFET? ›

To drive a P-Channel MOSFET, you have to define one of the Arduino pins as OUTPUT and set it to HIGH to turn it OFF and set it to LOW to turn it ON. HIGH state is OFF because the Source pin of the MOSFET is connected to the 5V output of the Arduino.

What is the working principle of P-channel E MOSFET? ›

The minimum voltage at which current starts flowing through it is called as threshold voltage (VT). The working of p-channel E-MOSFET is exactly opposite to that of p-channel E-MOSFET, i.e., all voltage polarities are reversed and thus the flow of current is also reversed.

What is the most used P channel MOSFET? ›

The IRF9540 is the most common P-channel enhancement mode silicon gate MOSFET which is used by many electronics designers and hobbyists.

What is the function of P channel? ›

P-Channel MOSFETs, or metal-oxide-semiconductor field-effect transistors, play a crucial role in modern electronic circuit designs. These semiconductor devices are widely utilized for their ability to handle high voltages and power levels while offering efficient switching capabilities.

What are the advantages of P Mosfet? ›

One of the great advantages of the P-channel MOSFET characteristics is the simplified gate driving technique that often reduces overall cost. Infineon offers a large range of P-channel power MOSFET voltages.

How do I choose a P Mosfet? ›

Steps to select a power MOSFET
  1. Find out all the parameters of application, such as maximum voltage, maximum current, and operating temperature.
  2. Find out the total load of the circuit.
  3. Calculate peak current and peak load required for the MOSFET.
  4. Find out the efficiency of the system.
  5. Now calculate the load with losses.
Nov 4, 2022

How do you protect the P channel MOSFET? ›

An additional Zener diode is used to clamp the gate of the P−Channel MOSFET and protect it in the case of a too high voltage. It is also possible to use an N−Channel MOSFET for reverse polarity protection.

Is P channel MOSFET normally open? ›

Thus the enhancement-mode MOSFET is equivalent to a “normally-open” switch. The reverse is true for the p-channel enhancement MOS transistor. When VGS = 0 the device is “OFF” and the channel is open.

What is the threshold voltage for P MOSFET? ›

The threshold in any given MOSFET will be somewhere between -1V and -3V. So if you buy a bag of 3 MOSFETs, one might have a threshold of -1.5V, one might be -2V, and the last might have a threshold of -2.5V.

When to use p channel MOSFET? ›

Then the P-channel MOSFET is used to switch the positive supply to the motor for forward direction (high-side switching) while the N-channel MOSFET is used to switch the negative supply to the motor for reverse direction (low-side switching).

What is the condition for P channel MOSFET? ›

P-channel MOSFET: When the gate voltage is lower than the source voltage by |Vth|, the p-channel MOSFET turns on. The following figure shows an inverter, a basic building block of CMOS logic ICs. When VIN is at the VCC or GND level, either the p-channel or n-channel MOSFET is off.

What are the majority carriers in P channel MOSFET? ›

The charge carriers that are present in large quantity are called majority charge carriers. In a p- type semiconductor, the majority charge carriers are the holes whereas in the n- type semiconductor, the majority charge carriers are the free electrons.

What is the difference between n and p channel MOSFET? ›

The key distinction lies in their reverse doping profiles: p-channel MOSFETs rely on holes as the majority charge carriers, generating hole current, while n-channel devices utilize electrons, creating electron current.

What is the P-type channel? ›

P-type calcium channels are voltage-dependent calcium channels that are classified under the high voltage activated class channel, along with L-, N-, Q- and R-type channels. These channels require a strong depolarization in order to be activated.

What is the basic construction of P channel depletion type MOSFET? ›

P-Channel Depletion MOSFET

In the P Channel depletion MOSFET, a small strip of semiconductor of P-type connects the source and drain. The source and drain are of P-type semiconductor and the Substrate is of N-type semiconductor. The majority of charge carriers are holes.

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