Mosfet

Discussion in 'The Projects Forum' started by RRITESH KAKKAR, Aug 28, 2010.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    What the Different b/w Depleted & enchanment mosfet I have readed there Construction but having Problem in practical How to Find It In mosfet pls Explain.......?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Take a look at the attached PDF.
    That will make things a lot more clear.

    Bertus
     
    RRITESH KAKKAR likes this.
  3. sceadwian

    New Member

    Jun 1, 2009
    499
    37
    Most Mosfets are enhancement mode, meaning that normally the channel is closed and the application of a postive or negative control voltage opens the channel. Depletion mode Mosfets are exactly the opposite, they're normally open at no bias and application of a negative voltage will close the channel. I don't believe there are depletion mode mosfets that work with a positive voltage. They're not widely used.
     
    RRITESH KAKKAR likes this.
  4. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    okk........!
     
  5. sceadwian

    New Member

    Jun 1, 2009
    499
    37
    Okay what? You asked!
    Study basic semi conductor physics. That document that Bertus posted seems to be pretty good. You don't have to understand all the math to read the plain text and general information to figure out what the difference is. It's generally speaking unimportant because the applications where depletion mode Mosfets are used are VERY few.
     
    RRITESH KAKKAR likes this.
  6. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    In Market There Is no Depleted Mosfet Why.......?
     
  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,685
    900
    There are depletion mode mosfets in the market. The demand is small and the market is small. Simple economics. Clare, Infineon, and IXYS have depletion mode mosfets listed on DigiKey (4 pages of products).

    John
     
    RRITESH KAKKAR likes this.
  8. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    Ok, Tell Me Where They Are Use........?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Sometimes they are used in amplification circuits where high input impedance and high gain are desired.

    Sometimes they are used in the feedback path of sine wave oscillators to act as automatic gain control, rather than using an incandescent bulb.

    Uses vary, but quite limited nowadays.
     
    RRITESH KAKKAR likes this.
  10. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    I have listen in Lecture That Emitter Has Low resistance Than Collector, But in Some 2n,Tip42c,Etc I found Collector resistance Low Than Emitter Why......./
     
  11. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    Pls tell......!
     
  12. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Where did you listen to the lecture? If it was in class, the professor should be able to clear everything up for you.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Resistance involves two points, resistance from what to the Emitter or Collector?

    Regardless, the answer is going to be because they built them that way, and for a reason.

    Doesn't your teacher accept questions?
     
  14. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    No, as I have not gone to him for asking it, you pls tell the resistance in small transister eg. BC558 the resistance b/w emitter - base junction is low while some transistor eg. TIP 42c has base-collector resistance low why pls explain......!
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Because that's how they made them, and for a reason probably having to do with what the transistor's intended circuit function was.

    He's probably not telling you the answer because:

    A) He doesn't know the answer either
    B) The answer is somewhere in the course material you're supposed to be learning on your own.
     
  16. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    You need to practice your tagline more often.
     
    RRITESH KAKKAR likes this.
  17. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
    2,831
    89
    Pls help me ......!
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    You've already been given the answer to both of your questions. If you want to get deeper in it please go find a textbook on semiconductor manufacturing physics - of course you'd also need a few years of physics and chemistry knowledge before that book would even make sense.

    There are no simple answers that could be put into words any further than whats already been said.
     
Loading...