Forward Characteristics Of Diodes

When the forward voltage is applied, in the initial part of the forward characteristic, the forward voltage is small enough to overcome the blocking effect of the electric field in the PN junction, and the forward current is almost zero. This section is called the dead zone. This forward voltage that does not make the diode conduct is called the dead-time voltage.

When the forward voltage is greater than the dead zone voltage, the electric field in the PN junction is overcome, the diode conducts forward, and the current increases rapidly as the voltage increases. In the current range of normal use, the terminal voltage of the diode remains almost unchanged when it is turned on, and this voltage is called the forward voltage of the diode.

When the forward voltage across the diode exceeds a certain value, the internal electric field is quickly weakened, the characteristic current increases rapidly, and the diode conducts forward. Called the threshold voltage or threshold voltage, the silicon tube is about 0.5V, and the germanium tube is about 0.1V. The forward voltage drop of the silicon diode is about 0.6~0.8V, and the forward voltage drop of the germanium diode is about 0.2~0.3V.