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Anonymous users2024-02-07A transistor is composed of two N-type or P-type diodes sandwiched between a layer of P-type or N-type diodes, and is divided into a collector, a base, and an emitter. The collector is responsible for replenishing the energy, the base is responsible for trigger control, and the emitter is responsible for output. Due to its special structure, the amount of electrons injected in the emission region is several times the amount of electrons at the base, when the base signal current is turned on, the emitter current emission is triggered, such as the base enters an electron, the emitter may flow out of several or hundreds of electrons, so as to achieve the so-called current amplification.
1) In order to facilitate the emission of electrons by the emission junction, the doping solubility of the semiconductor in the emission region is much higher than that of the semiconductor in the base region, and the area of the emission junction is small.
2) Although the emission area and the collector area are doped semiconductors of the same property, the doping solubility of the emission area is higher than that of the collector area, and the area of the collector junction is larger than that of the transmitting junction, which is convenient for collecting electrons.
3) The base region of the two PN junctions connecting the emission junction and the collector junction is very thin, and the doping solubility is also very low.
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Anonymous users2024-02-06The main function of the transistor is current amplification, and its essence is that the transistor can control the large current of the collector through a very small change of base current.
Working principle: The current amplification effect of the triode is actually to use the small change of the base current to control the large change of the collector current. The power supply UB is applied to the emission junction through the resistor RB, so that the emission junction is in a positive position, and most of the carriers (free electrons) in the emission region continue to enter the base region through the emission junction through the emission junction, thus constituting the emission current IE.
Most of the carriers in the base region are also diffused in the emission region, but since the density of most of the carriers is much lower than that of the carrier in the emission region, it can be regarded as the main electron flow.
Under the influence of this difference, electrons diffuse to the collector junction in the base region and are absorbed into the collector region to form a collector current IC. In addition, due to the thinner base region, the electrons bind to the holes in the base region, and the ratio of the difused electron flow to the recombined electron flow determines its amplification performance.
Transistor symbol
The word symbol of the transistor is generally represented by the letter QR or Q in foreign countries, and VT or V in China. Triode parameters Chinese symbol English comparison: PCM collector maximum power dissipation; The maximum allowable current of the ICM collector.
When the V(br)CBO emitter is open, the reverse breakdown voltage between the collector and the base. When the V(br)CEO base is open, the reverse breakdown between the collector and the emitter is pressurized. When the V(br)EBO collector is open, the reverse breakdown between the emitter and the base contains the canopy voltage.
When the ICBO emitter is open, the leakage current of the reverse letter between the collector and the base.
In order to make the transistor work in the amplified state, a bias resistance and a collector resistance are set in the triode circuit, and the output voltage is obtained by dividing the voltage of two resistors, which is a fixed bias amplification circuit, and there is a partial bias amplification circuit. I've been studying lately, so I can only explain that, and there's a lot more to come. It's complicated.
Forward bias: The voltage at the p-terminal is higher than that at the n-terminus. >>>More
The working principle of the transistor is actually similar to that of the faucet, so it is easy to understand!
The inventor of the vacuum triode was the American scientist Lee de Forest (1873 - 1961). In 1904, Fleming invented the first electron tube by adding a plate pole in front of the wire (filament) heated in a vacuum He called this kind of electron tube with two poles diode Using the newly invented electron tube, the current can be rectified, so that the ** receiver or other recording device can work Nowadays, when we turn on an ordinary tube radio, we can easily see the tube with the filament burned red It is the heart of the work of electronic equipment and the starting point of the development of the electronics industry.
Semiconductor transistors.
When used for AC amplification, the current amplification factor is frequency-dependent. When the operating frequency of the transistor is low, the HFE value does not change much, but when the transistor is used in a high-frequency circuit, the current amplification coefficient will continue to decrease with the increase of the operating frequency, and the frequency characteristic parameters need to be considered. The frequency characteristic parameters are mainly as follows. >>>More