Robotics Team 20 days learning punch day4 Taiyuan University of Technology (analog circuits preliminary)
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A preliminary understanding of the bipolar transistor
The two back to back into a crystal structure PN obtain a voltage, a current or a signal gain of the transistor. Depending on the power transistor is divided into three small large power.
Structure and type of the transistor
Manufactured according to different doping a silicon wafer in the same manner as the three doped regions, and the two PN junctions are formed, constitutes a transistor.
And the transistor is divided into two types (NPN and PNP)
Current amplification of transistor
Electrical signals obtained from the sensors are very weak, and only after amplification before further processing, or so that it has sufficient energy to drive the actuator. Today amplifying transistor is a core circuit.
FIG basic amplifying circuit,
ΔuI input voltage signal, which access the base - emitter circuit called an input circuit; signal amplified in the collector - emitter circuit, called the output circuit. Since the common emitter terminal is the two circuits, so that the circuit is a common-emitter amplifier. Because the transistor operates in external conditions is enlarged state emitter junction forward biased and the collector junction is reverse biased, so additional base in the input circuit should supply VB B; in the output circuit should be added to the collector source VC C. VCC and V BB polarity should 1.3.3 shown in FIG, and VC C is greater than VB B. Amplification transistor as small base current to collector current can be controlled with
Internal movement of carriers transistor
Internal movement of carriers
Because the emitter forward voltage is applied, and because of the high impurity concentration emitter regions, so that a large number of free electrons due to diffusion moved over the emitter reach the base region. At the same time, positive holes from the base region to the emitter diffusion region, but because of the low impurity concentration of the base region, the hole is formed so that the current is very small, negligible when the approximation. Be seen, the formation of the emitter diffusion motion current I.
I understand a lot of things are not in place, welcome criticism and pictures from the "Analog Electronics" child poem white version of my book is based on self-study
