MOSFET construction
$begingroup$
I've just read an application note and I was confused about this sentence:
"Engineers often think of a MOSFET as a single power transistor, but it is a collection of thousands of tiny power FET cells connected in parallel."
How is this possible ? In every class I learned about the cross section of a MOSFET as a single bulk not as "a collection of thousands power FET cells".
So the question is: Is the application note refering to a special type of MOS or all of my life was a lie ?
transistors mosfet cmos
asked 3 hours ago
pantarheipantarhei
34010
$endgroup$
add a comment |
$begingroup$
I've just read an application note and I was confused about this sentence:
"Engineers often think of a MOSFET as a single power transistor, but it is a collection of thousands of tiny power FET cells connected in parallel."
How is this possible ? In every class I learned about the cross section of a MOSFET as a single bulk not as "a collection of thousands power FET cells".
So the question is: Is the application note refering to a special type of MOS or all of my life was a lie ?
transistors mosfet cmos
asked 3 hours ago
pantarheipantarhei
34010
$endgroup$
1
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago
add a comment |
$begingroup$
I've just read an application note and I was confused about this sentence:
"Engineers often think of a MOSFET as a single power transistor, but it is a collection of thousands of tiny power FET cells connected in parallel."
How is this possible ? In every class I learned about the cross section of a MOSFET as a single bulk not as "a collection of thousands power FET cells".
So the question is: Is the application note refering to a special type of MOS or all of my life was a lie ?
transistors mosfet cmos
asked 3 hours ago
pantarheipantarhei
34010
$endgroup$
I've just read an application note and I was confused about this sentence:
"Engineers often think of a MOSFET as a single power transistor, but it is a collection of thousands of tiny power FET cells connected in parallel."
How is this possible ? In every class I learned about the cross section of a MOSFET as a single bulk not as "a collection of thousands power FET cells".
So the question is: Is the application note refering to a special type of MOS or all of my life was a lie ?
transistors mosfet cmos
transistors mosfet cmos
asked 3 hours ago
pantarheipantarhei
34010
asked 3 hours ago
pantarheipantarhei
34010
edited 2 hours ago
pantarhei
asked 3 hours ago
pantarheipantarhei
34010
asked 3 hours ago
pantarheipantarhei
34010
asked 3 hours ago
pantarheipantarhei
34010
34010
1
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago
add a comment |
1
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago
1
1
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
If a very large MOSFET (i.e. with a very wide channel) was implemented as a single physical device, like the one you saw in class, then the gate electrode would be very long and thin. This would cause a significant RC delay down the gate and so the MOSFET would turn on and off very slowly. Furthermore, it would be difficult to put such a device in a package because it would be hundreds or thousands of times wider than it was long.
So, it is electrically superior and easier to handle the MOSFET if you break it up into many small MOSFETs. The source, drain, and gate terminals of all of these small devices are connected in parallel. The result is the same as if you had built one huge device.
In CMOS VLSI design these small devices are often called the "fingers" and are actually drawn as parallel structures. Alternate fingers can then share their source/drain regions. Power MOSFETs use other techniques for forming the individual small devices.
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
$endgroup$
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
add a comment |
$begingroup$
I guess this sentence is a reference to the structure of power MOSFETs, like International Rectifier’s HEXFET structure.
See for example http://www.rfwireless-world.com/Terminology/HEXFET-vs-MOSFET.html for more about the HEXFET structure.
answered 2 hours ago
user2233709user2233709
928210
$endgroup$
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
add a comment |
Your Answer
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
If a very large MOSFET (i.e. with a very wide channel) was implemented as a single physical device, like the one you saw in class, then the gate electrode would be very long and thin. This would cause a significant RC delay down the gate and so the MOSFET would turn on and off very slowly. Furthermore, it would be difficult to put such a device in a package because it would be hundreds or thousands of times wider than it was long.
So, it is electrically superior and easier to handle the MOSFET if you break it up into many small MOSFETs. The source, drain, and gate terminals of all of these small devices are connected in parallel. The result is the same as if you had built one huge device.
In CMOS VLSI design these small devices are often called the "fingers" and are actually drawn as parallel structures. Alternate fingers can then share their source/drain regions. Power MOSFETs use other techniques for forming the individual small devices.
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
$endgroup$
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
add a comment |
$begingroup$
If a very large MOSFET (i.e. with a very wide channel) was implemented as a single physical device, like the one you saw in class, then the gate electrode would be very long and thin. This would cause a significant RC delay down the gate and so the MOSFET would turn on and off very slowly. Furthermore, it would be difficult to put such a device in a package because it would be hundreds or thousands of times wider than it was long.
So, it is electrically superior and easier to handle the MOSFET if you break it up into many small MOSFETs. The source, drain, and gate terminals of all of these small devices are connected in parallel. The result is the same as if you had built one huge device.
In CMOS VLSI design these small devices are often called the "fingers" and are actually drawn as parallel structures. Alternate fingers can then share their source/drain regions. Power MOSFETs use other techniques for forming the individual small devices.
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
$endgroup$
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
add a comment |
$begingroup$
If a very large MOSFET (i.e. with a very wide channel) was implemented as a single physical device, like the one you saw in class, then the gate electrode would be very long and thin. This would cause a significant RC delay down the gate and so the MOSFET would turn on and off very slowly. Furthermore, it would be difficult to put such a device in a package because it would be hundreds or thousands of times wider than it was long.
So, it is electrically superior and easier to handle the MOSFET if you break it up into many small MOSFETs. The source, drain, and gate terminals of all of these small devices are connected in parallel. The result is the same as if you had built one huge device.
In CMOS VLSI design these small devices are often called the "fingers" and are actually drawn as parallel structures. Alternate fingers can then share their source/drain regions. Power MOSFETs use other techniques for forming the individual small devices.
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
$endgroup$
If a very large MOSFET (i.e. with a very wide channel) was implemented as a single physical device, like the one you saw in class, then the gate electrode would be very long and thin. This would cause a significant RC delay down the gate and so the MOSFET would turn on and off very slowly. Furthermore, it would be difficult to put such a device in a package because it would be hundreds or thousands of times wider than it was long.
So, it is electrically superior and easier to handle the MOSFET if you break it up into many small MOSFETs. The source, drain, and gate terminals of all of these small devices are connected in parallel. The result is the same as if you had built one huge device.
In CMOS VLSI design these small devices are often called the "fingers" and are actually drawn as parallel structures. Alternate fingers can then share their source/drain regions. Power MOSFETs use other techniques for forming the individual small devices.
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
answered 2 hours ago
Elliot AldersonElliot Alderson
6,13611018
6,13611018
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
add a comment |
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Does the BJT transistor package have the same internal structure ?
$endgroup$
– pantarhei
1 hour ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
$begingroup$
Sorry, I don't have experience in BJT design.
$endgroup$
– Elliot Alderson
10 mins ago
add a comment |
$begingroup$
I guess this sentence is a reference to the structure of power MOSFETs, like International Rectifier’s HEXFET structure.
See for example http://www.rfwireless-world.com/Terminology/HEXFET-vs-MOSFET.html for more about the HEXFET structure.
answered 2 hours ago
user2233709user2233709
928210
$endgroup$
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
add a comment |
$begingroup$
I guess this sentence is a reference to the structure of power MOSFETs, like International Rectifier’s HEXFET structure.
See for example http://www.rfwireless-world.com/Terminology/HEXFET-vs-MOSFET.html for more about the HEXFET structure.
answered 2 hours ago
user2233709user2233709
928210
$endgroup$
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
add a comment |
$begingroup$
I guess this sentence is a reference to the structure of power MOSFETs, like International Rectifier’s HEXFET structure.
See for example http://www.rfwireless-world.com/Terminology/HEXFET-vs-MOSFET.html for more about the HEXFET structure.
answered 2 hours ago
user2233709user2233709
928210
$endgroup$
I guess this sentence is a reference to the structure of power MOSFETs, like International Rectifier’s HEXFET structure.
See for example http://www.rfwireless-world.com/Terminology/HEXFET-vs-MOSFET.html for more about the HEXFET structure.
answered 2 hours ago
user2233709user2233709
928210
answered 2 hours ago
user2233709user2233709
928210
answered 2 hours ago
user2233709user2233709
928210
answered 2 hours ago
user2233709user2233709
928210
928210
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
add a comment |
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
I'm conflicted on whether to flag this as spam or not, because it seems like you might just not know any better, but this seems an awful lot like you're advertising the HEXFET technology by pointing it out in particular when in fact all power FETs (that I'm aware of, anyway) use a structure like this.
$endgroup$
– Hearth
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@Hearth IMHO this is not spam and a spam flag would be inappropriate here--HEXFET can very well be a representative example of a power MOSFET structure. It points out the example fairly neutrally and points to a third-party source that discusses the structure and properties of this particular technology (as opposed to simply advertising it). That said, this answer can benefit from inclusion of relevant portions of the article (such as the structure diagram or a description thereof) to avoid being an effectively link-only answer.
$endgroup$
– Andrey Akhmetov
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@AndreyAkhmetov I’d rather not copy-paste portions of that article without permission from its author. But i’d be happy to up-vote an answer that’s more comprehensive than mine (and even delete mine).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
$begingroup$
@Hearth I just don’t know better. I just guessed other manufacturers used similar structures (but I have no idea how much similar).
$endgroup$
– user2233709
2 hours ago
add a comment |
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1
$begingroup$
A discrete MOSFET that you buy from digi-key or mouser is going to be thousands of parallel FETs--each one of which is represented by that cross section you learned about in class.
$endgroup$
– Hearth
2 hours ago
$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
2 hours ago