Forward biased ideal diode=>no voltage drop?

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Homework Help Overview

The discussion revolves around the characteristics of an ideal diode when it is forward biased, specifically addressing whether it exhibits any voltage drop. Participants explore the implications of defining an ideal diode in terms of voltage and current behavior.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Some participants question the definition of forward bias in relation to zero voltage, while others discuss the practical implications of assuming an ideal diode in circuit calculations. There are mentions of real-world diode behavior versus ideal conditions.

Discussion Status

The conversation includes varying perspectives on the concept of an ideal diode, with some participants suggesting that the zero voltage drop is a theoretical construct. There is ongoing exploration of how this assumption affects circuit design, particularly in high voltage scenarios.

Contextual Notes

Participants note the distinction between ideal and real diodes, with references to typical voltage drops in silicon diodes and the context in which ideal assumptions are applied. The discussion highlights the complexity of defining forward bias in practical terms.

pyroknife
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Forward biased "ideal" diode=>no voltage drop?

Does a forward biased ideal diode have no voltage drop?
 
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Yes, although it is difficult to say how zero volts can be called forward bias.
 
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:
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.
 
An ideal diode would have the vertical forward conducting line on the "Y" axis not to the right of it as these graphs show.
 
vk6kro said:
Yes, although it is difficult to say how zero volts can be called forward bias.

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
 

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