Forward biased ideal diode=>no voltage drop?

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SUMMARY

An ideal diode, when forward biased, is defined to have no voltage drop, which is a theoretical concept used in circuit analysis. While real diodes, such as silicon diodes, exhibit a forward voltage drop of approximately 0.7 V, the ideal diode simplifies calculations in high voltage designs where this drop is negligible. The ideal diode conducts perfectly in one direction without any forward voltage drop and blocks current in the reverse direction without leakage. This model is particularly useful in scenarios where the actual voltage across the diode is not significant to the overall circuit performance.

PREREQUISITES
  • Understanding of diode characteristics and behavior
  • Familiarity with forward and reverse bias concepts
  • Knowledge of circuit analysis techniques
  • Basic principles of semiconductor physics
NEXT STEPS
  • Study the characteristics of real diodes, focusing on silicon and Schottky diodes
  • Learn about the impact of forward voltage drop in practical circuit designs
  • Explore high voltage circuit design principles and their implications on diode selection
  • Investigate the use of ideal diode models in simulation software
USEFUL FOR

Electrical engineers, circuit designers, and students studying semiconductor devices will benefit from this discussion, particularly those interested in diode applications and circuit analysis.

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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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