MOSFET construction












3












$begingroup$


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







share|improve this question











$endgroup$








  • 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
    41 mins ago










  • $begingroup$
    Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
    $endgroup$
    – sstobbe
    6 mins ago
















3












$begingroup$


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







share|improve this question











$endgroup$








  • 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
    41 mins ago










  • $begingroup$
    Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
    $endgroup$
    – sstobbe
    6 mins ago














3












3








3





$begingroup$


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







share|improve this question











$endgroup$




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






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 21 mins ago







pantarhei

















asked 1 hour ago









pantarheipantarhei

33010




33010








  • 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
    41 mins ago










  • $begingroup$
    Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
    $endgroup$
    – sstobbe
    6 mins ago














  • 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
    41 mins ago










  • $begingroup$
    Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
    $endgroup$
    – sstobbe
    6 mins 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
41 mins 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
41 mins ago












$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
6 mins ago




$begingroup$
Most discrete power MOSFETs are actually VDMos devices versus planar devices, which are slightly different
$endgroup$
– sstobbe
6 mins ago










2 Answers
2






active

oldest

votes


















3












$begingroup$

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.






share|improve this answer









$endgroup$





















    1












    $begingroup$

    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.






    share|improve this answer









    $endgroup$













    • $begingroup$
      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
      36 mins 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
      33 mins 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
      18 mins 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
      15 mins ago











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    2 Answers
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    2 Answers
    2






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    active

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    3












    $begingroup$

    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.






    share|improve this answer









    $endgroup$


















      3












      $begingroup$

      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.






      share|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        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.






        share|improve this answer









        $endgroup$



        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.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 24 mins ago









        Elliot AldersonElliot Alderson

        6,10611018




        6,10611018

























            1












            $begingroup$

            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.






            share|improve this answer









            $endgroup$













            • $begingroup$
              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
              36 mins 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
              33 mins 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
              18 mins 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
              15 mins ago
















            1












            $begingroup$

            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.






            share|improve this answer









            $endgroup$













            • $begingroup$
              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
              36 mins 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
              33 mins 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
              18 mins 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
              15 mins ago














            1












            1








            1





            $begingroup$

            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.






            share|improve this answer









            $endgroup$



            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.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 42 mins ago









            user2233709user2233709

            918210




            918210












            • $begingroup$
              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
              36 mins 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
              33 mins 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
              18 mins 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
              15 mins 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
              36 mins 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
              33 mins 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
              18 mins 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
              15 mins 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
            36 mins 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
            36 mins 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
            33 mins 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
            33 mins 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
            18 mins 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
            18 mins 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
            15 mins 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
            15 mins ago


















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            Tårekanal

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            Tåreapparatet ( a ) Tårekjertel ( b ) Øvre tårepunkt ( c ) Øvre tårekanalikkel ( d ) Tåresekk ( e ) Nedre tårepunkt ( f ) Nedre tårekanalikkel ( g ) Tårekanal Tårekanalen eller nase-tårekanalen (av latin ductus nasolacrimalis ) er ein ductus som frakter overflødige tårer frå tåresekken til nasehola. Opninga inn mot nedre nasegang er delvis tildekt av ei ufullstendig slimhinnefold kalla Hasners ventil. Overflødige tårer strøymer gjennom tårekanalen og trekker inn i nedre nasegang. Dette er grunnen til at ein kan få rennande nase når ein gret, og at ein somme gonger kan kjenne saltsmaken av tårer i munnen. Både tårekanalen og tåresekken er tekt med fleirlaga sylinderepitel som inneheld slimproduserande begerceller, og er begge omgjevne av bindevev. Dakryostenose (tårekanalstenose) er ei innsnevring av tårekanalen som fører til epifora, ei overflod av tårer. Medfødd dakryostenose kan føra til cystisk utviding av tårekanalen ved at det dannast ein dakryocystocele. Personar m...
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