Last Updated on October 22, 2023 by Kevin Chen
MOSFET image source Apongee
MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are a type of transistor used in many electronic circuits. They are used to control the flow of current in a circuit and can be either N-channel or P-channel. But what are the differences between them? How are they used and does the difference matter? In this guide, we are going to discuss the differences between the n-channel and the p-channel MOSFET. From there, you will know which one to use and where to buy it.
Overview of a MOSFET
MOSFET is a type of transistor that is used to control the flow of current in a circuit. It is made up of three terminals: the source, the gate, and the drain. The source and drain are connected to a voltage source, while the gate is connected to a control signal. When a voltage is applied to the gate, it creates an electric field that controls the flow of current between the source and drain.
What is N channel MOSFET?
This is a type of MOSFET in which the majority of the charge carriers are electrons. When the MOSFET is switched on, the electrons will facilitate the maximum flow of current.It is used in circuits where the current needs to be switched on and off quickly. The N channel MOSFET has a low threshold voltage, meaning that it can be switched on with a relatively low voltage. There are two types of N-channel MOSFETS. These are: -N-Channel with Enhancement MOSFET -N-Channel with depletion MOSFET
How does N-Channel MOSFET work?
To know how N-Channel MOSFET works, it is important to separate the Enhancement and Depletion MOSFETs.
N-Channel with enhancement MOSFET
In this type of –channel MOSFET, the body is mainly dominated by the p-substrate. Therefore, the n-material is required to form the terminals which will be the source and the drain. The p substrate is connected to the gate terminal. When a positive voltage is applied to the gate, it creates an electric field that attracts electrons from the n-material and forms a channel between the source and drain. This allows current to flow through the MOSFET.
N-Channel with depletion MOSFET
In this type of N-Channel MOSFET, the body is mainly dominated by the n-substrate. Therefore, the p-material is required to form the terminals which will be the source and the drain. The n substrate is connected to the gate terminal. When a negative voltage is applied to the gate, it creates an electric field which repels electrons from the p-material and forms a channel between the source and drain. This allows current to flow through the MOSFET.
What is P channel MOSFET?
This is a type of MOSFET in which the majority of the charge carriers are holes. When the MOSFET is switched on, the holes will facilitate the maximum flow of current. It is used in circuits where the current needs to be switched on and off quickly.
The P channel MOSFET has a high threshold voltage, meaning that it requires a higher voltage to be switched on.
There are two types of P-channel MOSFETS. These are: -P-Channel with Enhancement MOSFET -P-Channel with depletion MOSFET
How does P-Channel MOSFET work?
Image source HomoFaciens
Just like in the n-channel MOSFET, the working principle in the P-channel will depend on the type: Enhancement MOSFET or depletion MOSFET.
P-channel with enhancement MOSFET
The working principle of this type of p-channel MOSFET is the same as the N-channel with enhancement MOSFET. The body is mainly dominated by the n substrate and therefore, the p material is required to form the terminals which will be the source and the drain.
The n substrate is connected to the gate terminal. When a positive voltage is applied to the gate, it creates an electric field which attracts holes from the p-material and forms a channel between the source and drain. This allows current to flow through the MOSFET.
P-channel with depletion MOSFET
In this type of P-Channel MOSFET, the body is mainly dominated by the p-substrate. Therefore, the n-material is required to form the terminals which will be the source and the drain. The p substrate is connected to the gate terminal. When a negative voltage is applied to the gate, it creates an electric field which repels holes from the n-material and forms a channel between the source and drain. This allows current to flow through the MOSFET.
Comparing N Channel MOSFET vs P Channel MOSFET
Now that we have discussed the detailed features of the two, we can go ahead to compare them using various parameters.
Packing density
Packing density refers to the number of devices that can be fitted in a given area. In this regard, N-channel MOSFETs are better than P-channel MOSFETs as they possess higher packing density due to their smaller size.
With a better packing density, it means that N channel MOSFETs are more efficient in terms of space utilization.
Switching Speed
Another parameter that must be considered when comparing the two is switch speed. Here, N-channel MOSFETs are faster than P-channel ones followed by an overall better performance at high frequencies.
This makes them suitable for high-speed applications.
Power Dissipation
When it comes to power dissipation, P-channel MOSFETs are more efficient than N-channel ones. This is because the threshold voltage in P channel MOSFETs is usually higher, meaning that less power will be lost when turning them on and off.
ON resistance
The ON resistance of a MOSFET is the resistance between the source and drain when it is turned on. In this regard, N-channel MOSFET has a lower ON resistance than the p-channel MOSFET. This is mainly because of the higher packing density of n channel MOSFETs.
This means that they will be able to handle more current than P-channel MOSFETs, making them suitable for high-power applications.
Energy-efficient
Well, we can define the energy efficiency of a MOSFET as the amount of power it consumes to function. This means that N-channel MOSFETs are more energy efficient than p-channel ones. This is because they have a lower threshold voltage and therefore, require less voltage for switching on.
This feature plays a great role when it comes to battery-powered devices as it can help to increase battery life.
Complexity
In terms of complexity, p-channel MOSFETs are a bit more complex than n-channel ones. This is mainly due to the use of two different materials in their construction. With this complexity comes an increase in production costs, making P-channel MOSFETs slightly more expensive than N-channel ones.
Application
Which applications require N-channel MOSFETs and which ones require P-channel MOSFETS? Well, they both have their own unique features that make them suitable for different applications.
N-channel MOSFETs are usually used in high-power and high-speed applications such as motor control, switching power supplies, and amplifier circuits. On the other hand, P-channel MOSFETs generally find use in low-power applications such as battery-powered devices, logic circuits, and voltage regulators.
Price
Is there a difference in price between these two MOSFET types? Generally, N-channel MOSFETs are cheaper than P-channel ones due to their smaller size and higher packing density. In addition, they can be easily mass-produced since the fabrication process is simpler for them.
Frequently Asked Questions About P-channel and n-channel MOSFETs
Here are some of the questions that most people tend to ask about n-channel MOSFET and P-channel MOSFET
How do I distinguish MOSFET? Is it P-channel or n-channel?
The easiest way to tell if a MOSFET is P-channel or N-channel is by looking at its symbol. A P-channel MOSFET will have an arrow pointing toward the gate while an N-channel MOSFET will have an arrow pointing away from it.
Another way of distinguishing them is by their respective threshold voltages. N-Channel MOSFETs usually have a lower threshold voltage than P-channel ones, meaning that they will require less voltage for switching on.
What types of applications are suitable for N-channel MOSFET and P-channel MOSFET?
N-channel MOSFETs are mainly used for high-speed and high-power applications such as motor control, switching power supplies, and amplifier circuits. On the other hand, P-channel MOSFETs generally find use in low power applications such as battery-powered devices, logic circuits, and voltage regulators.
Can I use n-channel MOSFET instead of P-channel?
Yes, you can use an N-channel MOSFET instead of a P-channel one. However, it is important to note that the threshold voltage for the N-channel MOSFET should be higher than that of the P-channel one in order for it to work properly.
Also, due to their lower packing density, N-channel MOSFETs are not suitable for high power applications.
Why is n-channel MOSFET preferred over p-channel MOSFET?
N-channel MOSFETs are preferred over P-channel ones for several reasons. Firstly, they have a higher packing density which allows them to handle more current than P-channel MOSFETs, making them suitable for high-power applications.
In addition, N-channel MOSFETs are more energy efficient than p-channel ones due to their lower threshold voltage which requires less voltage for switching on. This feature plays a great role when it comes to battery-powered devices as it can help to increase battery life.
Finally, N-channel MOSFETs are usually cheaper than P-channel ones due to their smaller size and simpler fabrication process.
Conclusion
P-channel and N-channel MOSFETs are two types of transistors with distinct features that make them suitable for different applications.
And in case you are planning to buy a MOSFET for your application, let ICRFQ be your partner. We are a reputable supplier of transistors in China. Contact us and place your order.
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