is that electronic device consists of three extrinsic semiconductor materials, so PNP or NPN, ie material portion of N, P material followed, then another portion of material N, NPN type, and similarly in the PNP, but with inverse semiconductor materials. The BJT transistor is also known as bipolar transistor, because driving is through holes and electrons.
The central area is called the base, the other two are called the collector and emitter. The transmitter is built very narrow and doped, the base is narrower and less doped and the collector is the wider area. To protect the semiconductor material, the encapsulation used, which may be plastic, bakelite or metal. Despite the low power dissipation transistors have on certain occasions it is necessary to use heat sink for better cooling of the transistor.
transistor polarization
The unpolarized transistor can be regarded as two opposing diodes, with a potential barrier 0, 7 V for each diode. If both diodes are biased directly or inversely, should act or not allowing the flow of current as is known. The effect of amplification in the transistor is created directly polarizing the base-emitter and conversely the collector-base.
Being the emitter junction forward biased, allows the passage of holes (Ipe) of the emitter to the base, as well as electrons (Ine) passing from the base to emitter. The relationship between the hole current and electron current is proportional to the conductivity of P and N materials, in commercial transistors emitter doping is much higher, so the current in a pnp transistor is practically composed of hollow .
The polarization of the collector junction causes holes crossing the emitter junction be attracted by the negative potential of the collector and also repelled by the positive potential of the base, not all the holes that cross the emitter junction reach the collector, since recombination occurs in some of them in the area of \u200b\u200bthe base.
Materials & Equipment
practice were used for the following equipment and materials:
| Equipment | Materials |
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Operation and Analysis of Results
designed amplifier with bipolar transistor 2N2222, behaved excellently, the configuration used for mounting amplifier was the voltage divider.
The amplifier, achieving yield a voltage gain of -10, in perfect condition.
theoretical results:
Dc Analysis
R1 = 7K! Rc = 140! C1 = C2 = C3 = 47 f
R2 = 4K! Re = 1.5 K! = 100
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R2.Vcc/R1 + VR2 = R2 '= 3.63 v VR2
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Ib-Vbe = VR2 / (R1 Zi = 882317!
Results Practices
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Vb = 3.60 V to 0.72 Ib =
Vc Ic = 0.28 v = 1926 m
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Av = -10 -
Fb = 200 Hz fa = 5.3 Mhz -
Ab = 5.3 Mhz -
ANTONIO MORA NERWIN REINOSO
CI: 17,557,095 -
EES
- SECTION 1
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