ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 2
FIGURE 89. FORWARDBIASED JUNCTION IN AN NPN TRANSISTOR.
hole pairs. The minority carriers for the reversebiased PN
junction are the electrons in the P material and the holes in
the N material. These minority carriers actually conduct the
current for the reversebiased junction when electrons from the
P material enter the N material, and the holes from the N
material enter the P material. However, the minority current
electrons play the most important part in the operation of the
NPN transistor.
At this point it may be wondered why the second PN junction
(basetocollector) is not forward biased like the first PN
junction (emittertobase). If both junctions were forward
biased, the electrons would have a tendency to flow from each
end section of the NPN transistor (emitter and collector) to the
P section (base). In essence, we would have two junction diodes
possessing a common base, thus eliminating any amplification and
defeating the purpose of the transistor. A word of caution is
in order at this time. If the second PN junction is
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