1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Forward biased ideal diode=>no voltage drop?

  1. May 12, 2013 #1
    Forward biased "ideal" diode=>no voltage drop?

    Does a forward biased ideal diode have no voltage drop?
     
  2. jcsd
  3. May 13, 2013 #2

    vk6kro

    User Avatar
    Science Advisor

    Yes, although it is difficult to say how zero volts can be called forward bias.
     
  4. May 13, 2013 #3

    ehild

    User Avatar
    Homework Helper
    Gold Member

    Of course, there is some voltage drop across a forward biased diode, but small. See the diode characteristics below.


    Rectifier_vi_curve.GIF

    When we speak abut an ideal diode, we either assume zero forward voltage or constant (0.7 V for Si diodes).


    a13_clip_image002.JPG
    ehild
     
    Last edited: May 13, 2013
  5. May 13, 2013 #4

    vk6kro

    User Avatar
    Science Advisor

    The "ideal diode" is a convenient fiction which is used when the actual voltage across the diode doesn't matter enough to be included in a calculation.

    This is often the case in high voltage designs where the 0.7 volt drop across the diode is trivial compared with the much higher voltages in the circuit.

    A voltage of zero volts can't have a polarity.
     
  6. May 13, 2013 #5

    vk6kro

    User Avatar
    Science Advisor

    An ideal diode would have the vertical forward conducting line on the "Y" axis not to the right of it as these graphs show.
     
  7. Nov 11, 2013 #6
    Ideal diode has zero volts with non-zero forward current. "Forward biased" refers to direction of conduction current. An ideal diode conducts perfectly in 1 direction (no forward voltage drop). It blocks perfectly in reverse (no leakage current).

    Ideal diode has zero volts with non-zero amps in forward direction, vice-versa in reverse.

    Did this help?

    Claude
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Forward biased ideal diode=>no voltage drop?
  1. Voltage Drops (Replies: 2)

  2. Voltage drop (Replies: 2)

  3. Forward/Reverse Bias (Replies: 5)

Loading...