Contents
What are the capacitances in a diode?
The variable-capacitance diode is a product that makes use of the capacity characteristics of the depletion layer. The depletion layer occurs in the pn junction of the diode when the voltage is applied in the reverse direction, and the thickness varies in proportion to the reverse voltage.
When diode is forward biased it is equivalent to?
When the diode is forward biased it is equivalent to a closed switch in series with a small equivalent voltage source equal to the barrier potential (0.6 V for Silicon, 0.2 for germanium) with the positive side towards the anode.
When a diode is forward biased barrier potential?
When p-n junction diode is forward biased, more number of charge carriers (electrons in n-side and holes in p-side) moves through the junction. Therefore, in forward biasing barrier potential is reduced. Thus, increasing the current in the circuit.
What is the knee voltage of Si diode?
about 0.7 volts
The knee voltage for silicon diodes is about 0.7 volts, which is due to the properties of silicon when doped to form P-N junctions. Almost all diodes are made of silicon, except when specific other characteristics are needed (e.g., germanium diodes have lower threshold voltages around 0.3 volts).
What will happens to potential barrier in forward bias?
The forward bias voltage opposes the potential barrier. Due to this, the potential barrier is reduced and hence the depletion layer becomes thin. The conduction across p-n junction takes place due to migration of majority carriers from one region to another.
What happens when you increase the forward voltage of a diode?
When you increase the current, the forward voltage also increases (here: 1N400x): And when you increase the current even further, the power dissipation becomes too large, and the diode eventually becomes a LED (light-emitting diode) and shortly afterwards a SED (smoke-emitting diode).
What does the slope of a diode look like?
The diode has become a small resistor “switch” and can therefor be referred to as ON. The full voltage current relationship of a diode looks like this. The slope before the knee is the forward off conductance (1/R), the slope past the knee is the forward ON conductance.
Can you apply voltage higher than this barrier potential?
The point is that you can’t “apply a voltage higher than this barrier potential”, the diode doesn’t let you.
Why is the depletion region of a diode smaller?
The reason is that the depletion region of a diode (with zero voltage applies) creates the barrier potential, as you already noted, of about 0.7V (assuming a typical Silicon diode). As you apply forward voltage, the depletion region becomes smaller.