Question
Explain the I-V characteristic of a forward biased junction diode.
✓
Answer
- Figure given below shows the I-V characteristic of a forward biased diode.
- When connected in forward bias mode, initially, the current through diode is very low and then there is a sudden rise in the current.
- The point at which current rises sharply is shown as the ‘knee’ point on the I-V characteristic curve.
- The corresponding voltage is called the knee voltage. It is about 0.7 V for silicon and 0.3 V for germanium.
- A diode effectively becomes a short circuit above this knee point and can conduct a very large current.
- To limit current flowing through the diode, resistors are used in series with the diode.
- If the current through a diode exceeds the specified value, the diode can heat up due to the Joule’s heating and this may result in its physical damage.
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