Operation Of The Bipolar Junction Transistor
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Operation Of The Bipolar Junction Transistor

Figure 122.2(a) and 122.2(b) illustrate the two primary types of the Bipolar Junction Transistor (BJT): pnp BJT transistor and the npn BJT transistor. Figure 122.2(c) and 122.2(d) illustrate its operation. The + superscript indicates additional doping (the addition of impurities to semiconductors).

(a) The operation of the BJT is defined in terms of two currents and two voltages. Identify these currents and voltages and indicate the relationship between them.

(b) There are four basic regions that define the operating states of a BJT. Name the regions.

The strings: S7P5A51 (Physical Change).

The math:
Pj Problem of Interest is of type change (physical change). Transistors are primarily used for signal amplification and switching. Both are change problems.

(a) The operation of the Bipolar Junction Transistor is defined by the Base current (iB), the Collector current (iC), the Collector-Emitter voltage (VCE) and the Base-Emitter voltage (VBE).
iE = iB + iC
VCE = VBE + VCB

(b) The four basic operating regions of the Bipolar Junction Transistor are:
(i) The cutoff region: both BJT junctions are reversed-biased, base current is very small, and no collector current.
(ii) The active linear region: transistor acts as a linear amplifier. Base-emitter (BE) junction is forward-biased and collector-base (CB) junction is reversed-biased.
(iii) The saturation region: Both junctions are forward-biased.
(iv) The breakdown region: defines the physical limit of transistor.

Blessed are they that have not seen, and yet have believed. John 20:29