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Friday, January 13, 2012

ADVANTAGE & DISADVANTAGE OF TUNNEL DIODE


One of the main reasons for the early success of the

tunnel diode was its high speed of operation and the

high frequencies it could handle. This resulted from

the fact that while many other devices are slowed

down by the presence of minority carriers, the tunnel

diode only uses majority carriers, i.e. holes in an

n-type material and electrons in a p-type material.

The minority carriers slow down the operation of a

device and as a result their speed is slower. Also

the tunnelling effect is inherently very fast.

The tunnel diode is rarely used these days and this

results from its disadvantages. Firstly they only

have a low tunnelling current and this means that

they are low power devices. While this may be

acceptable for low noise amplifiers, it is a

significant drawback when they are sued in

oscillators as further amplification is needed and

this can only be undertaken by devices that have a

higher power capability, i.e. not tunnel diodes. The

third disadvantage is that they are problems with the

reproducibility of the devices resulting in low

yields and therefore higher production costs.

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