MOSFET Symbol: Meaning of Arrow?

In summary, the arrow in the symbol of the MOSFET indicates the direction of normal current flow in the device.
  • #1
antonantal
243
21
What does the arrow in the symbol of the MOSFET indicate? I skipped the lecture when we were told this :smile: and I can't figure out myself. I mean if it were after me, I would have put that arrow to indicate the direction of the electric field, but the arrow actually points the oposite way. So what does that arrow actually stand for?
 
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  • #2
It denotes if the MOSFET is a PMOS or an NMOS.
 
  • #3
Maxwell said:
It denotes if the MOSFET is a PMOS or an NMOS.

That's not what I meant. For example in the case of a BJT the arrow indicates the direction of the emitter current in forward active regime. In the case of MOSFET what does it indicate?
 
  • #4
As Maxwell stated. Either P-channel or N- channel. See this http://encyclobeamia.solarbotics.net/articles/mosfet.html" .

Regards
 
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  • #5
dlgoff said:
As Maxwell stated. Either P-channel or N- channel. See this http://encyclobeamia.solarbotics.net/articles/mosfet.html" .

Again that's not what I'm asking.
Maybe I should put it this way: why is the arrow at the NMOS symbol directed towards the gate and the arrow at the PMOS directed away from the gate?
It must be an analogy with the direction of something. Like in the case of a BJT, the direction of the arrows for npn and pnp are put in analogy with the direction of the emitter current in forward active regime.
 
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  • #6
Like electric field lines, arrows are conventionally drawn to point from P to N.

- Warren
 
  • #7
chroot said:
Like electric field lines, arrows are conventionally drawn to point from P to N.

So what you mean is that, say for PMOS the arrow points from the channel (P region) towards the rest of the bulk (N region) in analogy with the direction of the electric field between this two regions of the bulk, which is exactly the opposite direction of the electric field initially applied between the gate and the bulk (ie the voltage between gate and bulk)?
 
  • #8
Well, in the abbreviated MOSFET symbols (where the body is assumed to be shorted to the source and isn't shown), the arrow indicates the direction of normal current flow in the device.
 
  • #9
Ok. Thanks for the help guys.
 
  • #10
Hole flow and electron flow??
 

1. What does the arrow in the MOSFET symbol represent?

The arrow in the MOSFET symbol represents the direction of current flow in the device. It points from the source to the drain, indicating that current flows from the source to the drain when the device is turned on.

2. What is the significance of the arrow in the MOSFET symbol?

The arrow in the MOSFET symbol is important because it shows the polarity of the device. The direction of the arrow determines whether the MOSFET is an N-channel or P-channel device, which affects its behavior and application in electronic circuits.

3. How does the arrow in the MOSFET symbol relate to the device's operation?

The arrow in the MOSFET symbol is directly related to the device's operation. It represents the flow of majority carriers (electrons for N-channel MOSFETs and holes for P-channel MOSFETs) from the source to the drain when a voltage is applied to the gate.

4. Can the arrow in the MOSFET symbol be ignored when using the device in a circuit?

No, the arrow in the MOSFET symbol cannot be ignored. It is a crucial part of the symbol and must be taken into consideration when using the device in a circuit. Ignoring the arrow can lead to incorrect connections and potentially damage the device.

5. Are there any other symbols that can be used to represent a MOSFET, besides the one with an arrow?

Yes, there are alternative symbols that can be used to represent a MOSFET. Some symbols may not include an arrow, but they still indicate the polarity of the device. It is important to refer to the datasheet or device specifications to ensure the correct symbol is used in a circuit.

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