In this topic, you study Biasing of PN Junction Diode – Definition, Theory & Diagram.
A PN junction diode connected to an external voltage source is called biased PN junction diode. By applying an external voltage across a diode, we are able to control the width Of the depletion layer. This allows to control the resistance of the diode and also the amount of current that can pass through the diode. Depending upon the polarity of d.c. voltage source connected to the diode, there are two types of biasing
(l) Forward bias, (2) Reverse bias.
Forward bias
In this case, the positive terminal of the voltage source is connected to the anode terminal and the negative terminal of the voltage source is connected to the cathode terminal of diode as shown in Fig. 7.5 (a).
Fig. 7.5 (a) : Forward bias
A large amount of current flows through the diode under this condition.
Reverse bias
In this case, the positive terminal Of the voltage source is connected to the cathode and the negative terminal to the anode as shown in Fig. 7.5 (b). Practically, no current flows through the junction under this condition.
Fig. 7.5 (b) . Reverse bias