# Homework Help: Forward biased ideal diode=>no voltage drop?

1. May 12, 2013

### pyroknife

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

Does a forward biased ideal diode have no voltage drop?

2. May 13, 2013

### vk6kro

Yes, although it is difficult to say how zero volts can be called forward bias.

3. May 13, 2013

### ehild

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

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

ehild

Last edited: May 13, 2013
4. May 13, 2013

### vk6kro

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.

5. May 13, 2013

### vk6kro

An ideal diode would have the vertical forward conducting line on the "Y" axis not to the right of it as these graphs show.

6. Nov 11, 2013

### cabraham

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