What are the characteristics and characteristics of the three-pole transistor circuit design?
The design of the transistor should pay attention to the characteristics of the design, and design according to the principles and theoretical knowledge of circuit design. There are many methods for the total circuit of transistors, but it is necessary to pay attention to the theoretical knowledge of circuit design. Therefore, for those who specialize in circuit design, they must learn professional knowledge, which will be of great help to their future work and life. Let's take a closer look at the characteristics and characteristics of the three-pole transistor circuit design.
The output characteristic curve of the triode transistor circuit design (common emitter). The crystal transistor is composed of three parts of semiconductors that form two PN junctions, and its composition forms are PNP type and NPN type. The germanium transistors produced in China are mostly PNP type, and the silicon transistors are mostly NPN type, and their structural principles are the same.
The triode has three areas and three electrodes. Among them, the base region (a thin semiconductor in the middle of the triode) leads to the base electrode b; on both sides, the emitter region leads to the emitter electrode e and the collector region leads to the collector electrode c. The PN junction between the launch zone and the base zone is called the launch junction, and the PN junction between the collector zone and the base zone is called the collector junction. On the circuit symbol, the PNP tube emitter arrow is inward, and the NPN tube emitter arrow is outward, indicating the current direction.
When the base current Ib is constant, the relationship curve between the transistor Ic and Uce is called the output characteristic curve. The curve is given by Ic (mA) as the ordinate and Uce (V) as the abscissa. The points on the graph represent the relationship between Ib, Uce and Ic when the transistor is working, which determines the working state of the transistor. It can be seen from the curve that the working state of the transistor can be divided into three regions. Saturated area: Uce is small, Ic is large. The collector and emitter are saturated and turned on as if they were short-circuited. Uce at this time is called saturation pressure drop. At this time, the emitter junction and collector junction of the transistor are in forward bias. Amplification area: A small change in Ib in this area can cause a large change in Ic, and the transistor works in this area to have an amplification effect. In this area, Ic is hardly controlled by Uce, and the curve is relatively flat. At this time, the emitter junction of the tube is in forward bias and the collector junction is in reverse bias. Cut-off area: Ib = 0, Ic is extremely small, the collector and emitter seem to be broken (called cut-off), and the emitter junction and collector junction of the tube are in reverse bias.
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