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How is the base collector junction of the transistor biased?
The biasing conditions are reversed so that the base collector junction is forward biased and the base emitter junctions is reverse biased, which switches the roles of the collector and emitter regions. The base contains a much lower reverse bias voltage than in the forward-active region.
What is cut off region in BJT?
Whenever we observe the terminals of a BJT and see that the emitter-base junction is not at least 0.6-0.7 volts, the transistor is in the cutoff region. In cutoff, the transistor appears as an open circuit between the collector and emitter terminals.
How does a BJT work in a bipolar junction transistor?
A BJT uses a small current at its base to control a much larger collector current. Before we go any further, it may be useful to define some important terms concerning the operation of a bipolar junction transistor.
How does a BJT work on a silicon wafer?
Instead, semiconductor manufacturers use a diffusion process which melts the base into the collector region and then melts the emitter region into the base region (for an NPN BJT). Thousands of transistors are diffused on a silicon wafer from which induvial transistors are then cut before being sealed in plastic or metal.
What are the three terminals of a BJT?
Recall that there are two main types of BJTs and that the BJT is a three terminal device, as we can see in figure 1. The three terminals are the base, collector, and emitter. Figure 1: the two main types of bipolar junction transistors are NPN and PNP.
How does the BJT work in saturation mode?
Saturation refers to a region of operation where maximum collector current flows and the BJT acts like a closed switch from collector to emitter. In this mode the BC junction forward biases and maximum current flows. The collector current cannot increase any more, even with an increase in base current.