How does the characteristic curve of a diode work?
This curve shows the variation of the diode current versus the voltage across the diode. On the right-hand side of the vertical axis (the current axis), a diode is forward biased because the voltage applied across it is positive. The left-hand side corresponds to reverse bias.
What are the vi characteristics of the PN junction diode?
The VI characteristics of PN junction diode in forwarding bias are nonlinear, that is, not a straight line. This nonlinear characteristic illustrates that during the operation of the N junction, the resistance is not constant. The slope of the PN junction diode in forwarding bias shows the resistance is very low.
Why does a diode have a forward bias?
On the right-hand side of the vertical axis (the current axis), a diode is forward biased because the voltage applied across it is positive. The left-hand side corresponds to reverse bias. When a diode is forward biased, the current across it has an abrupt increase as the voltage increases. This represents a small resistance to the current flow.
How is the threshold voltage of a diode determined?
Due to the non-linear nature of the graph, the precise threshold voltage is sometimes found through a little geometry with the curve. Actually, it is a very simple and non-painful procedure. There is a straight part to the diode characteristic graph. All you have to do is to extend this part until it crosses the x-axis (Vf).
When does the diode become a fully conducting state?
As we increase the voltage further, to ~0.7 V, and ~0.8 V, the diode reaches a fully conducting state, and the current flow through it rises very fast. As you can see in the graph, the curve is almost vertical at around 0.8 V.
When does the forward voltage drop on a diode?
This value tells you that the diode will continue conducting even when the voltage falls as low as that figure. What most people do not realise is that the forward voltage drop is ideally specified when the forward current is zero. This is when the curve cuts the x-axis and the current is zero.