Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

edr1c

how to estimate diode bulk resistance from I-V graph?

  • one year ago
  • one year ago

  • This Question is Closed
  1. nick67
    Best Response
    You've already chosen the best response.
    Medals 1

    Hi edr1c, as a rule of thumb you may evaluate the forward diode resistance as: \[R _{F}=\Delta V_{D} / \Delta I_{D}\] taking values from the quasilinear portion of the characteristic

    • one year ago
  2. edr1c
    Best Response
    You've already chosen the best response.
    Medals 0

    so by taking 2points above the turn on voltage for the diode, i will get the approximate resistance by taking their gradient?

    • one year ago
  3. nick67
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1340545927975:dw|

    • one year ago
  4. edr1c
    Best Response
    You've already chosen the best response.
    Medals 0

    does barrier potential comes into consideration when calculating this resistance? because the previous section asked us to estimate the barrier potential.

    • one year ago
  5. edr1c
    Best Response
    You've already chosen the best response.
    Medals 0

    the reason im raising the question is because i obtained a very high value for the resistance. Voltage, V1/V Current, I/mA 0.6 0.92 0.64 1.71 0.68 4.04 0.7 5.81 0.72 8.81 0.74 12.72 0.76 17.86 0.77 20.89 i got around 17ohm by taking the 2nd and 3rd point

    • one year ago
    1 Attachment
  6. nick67
    Best Response
    You've already chosen the best response.
    Medals 1

    Well, if you take points too close to the diode knee you have of course a greater resistance, because it is still going into forward bias; if you take last two points you have a resistance of about 3,3 Ohm; in this region the diode is in its linear zone

    • one year ago
  7. nick67
    Best Response
    You've already chosen the best response.
    Medals 1

    As for the barrier potential you could apply a reverse calculus taking values from last two points; you have there a diode voltage of about 0.76 V and a diode current of about 19 mA. If you subtract the voltage on the bulk resistance from the total diode voltage you can evaluate the barrier potential:\[V _{barrier} = V _{D} - R _{bulk} I _{D}\] that is 0.76 - 3.3 x 0.019 = 0.697 V

    • one year ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.