Working of Diode
The diode operates when a voltage signal is applied across its terminals. The application of a DC voltage to make the diode operate in a circuit is called as ‘Biasing’. As already mentioned above the diode resembles to that of a one way switch so it can either be in a state of conduction or in a state of non conduction. The ‘ON’ state of a diode is achieved by ‘Forward biasing’ which means that positive or higher potential is applied to the anode and negative or lower potential is applied at the cathode of the diode. In other words, the ‘ON’ state of diode has the applied current in the same direction of the arrow head. The ‘OFF’ state of a diode is achieved by ‘Reverse biasing’ which means that positive or higher potential is applied to the cathode and negative or lower potential is applied at the anode of the diode. In other words, the ‘OFF’ state of diode has the applied current in the opposite direction of the arrow head.
During ‘ON’ state, the practical diode offers a resistance called as the ‘Forward resistance’. The diode requires a forward bias voltage to switch to the ‘ON’ condition which is called Cut-in-voltage. The diode starts conducting in reverse biased mode when the reverse bias voltage exceeds its limit which is called as the Breakdown voltage. The diode remains in ‘OFF’ state when no voltage is applied across it.
A simple p-n juction diode is fabricated by doping p and n type layers on a silicon or germanium wafer. The germanium and silicon materials are prefered for diode fabrication because:
· They are available in high purity.
· Slight doping like one atom per ten million atoms of a desired impurity can change the conductivity to a considerable level.
· The properties of these materials change on applying heat and light and hence it is important in the devlopment of heat and light sensetive devices.
source: engineersgarage.com
No comments:
Post a Comment