I have this symbol that I really can't figure out what means. Help is very much appreciated!

enter image description here

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    \$\begingroup\$ That is a FET. Transistors of all flavours may be drawn with or without a circle around the "works". \$\endgroup\$ – Peter Bennett Sep 12 '15 at 22:27

That's an N-channel MOSFET, which is a bit like an NPN bipolar transistor but doesn't require any gate current.

The three terminals are Gate (at the left), Drain (at the top) and Source (at the bottom).

The Gate is equivalent to the base of a bipolar transistor, drain to the collector and the source to the emitter.

MOSFETs have a diode in parallel with the Drain and Source connections and that is shown in the symbol. There is a fair amount of variability with MOSFET symbols and they don't always show the diode.

A P-channel MOSFET has the arrow in the middle pointing the other way as well as the diode.


This is an NMOS, have a look here.

The part that might have mislead you is probably the diode from source to drain: this is called body diode and is a sort of side effect component. When you integrate a power mos on silicon you get that extra diode, that can somewhat sometimes be helpful.


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