TechnologiesElectronics

Some features of the current-voltage characteristic (CVC) of a diode

Any electronic device works in accordance with its characteristics. Using them when designing various devices of any complexity, you can make a mathematical model of a device. On this principle, programs are created that apply mathematical modeling and allow you to see the operation of the electronic circuit on the monitor screen. They greatly help in the development of instruments. By connecting to different nodes, virtual Oscilloscopes, you can verify the performance of the future product and, if necessary, make adjustments. On their basis, one can not only learn how to design electronic devices, but also learn some features in the work of the elements, deepen their theoretical knowledge. As an example, one can consider one of the basic elements in electronics based on the current-voltage characteristic, hereinafter the VAC of the diode. These devices are good in that there are several of them. All of them are successfully used in electronic circuits. These devices have proven themselves over the years in equipment for a variety of purposes.

For the first time such an element was assembled in its "tube" version and for quite a long time was used in the design of different schemes. Such devices are used in tube amplifiers, which are still produced by individual companies. The current-voltage characteristic of the diode in this case is described by the Bohuslavsky-Langmuir formula. According to this formula, the current flowing through the device is directly proportional to the voltage in the degree of three seconds multiplied by the coefficient. As you can see, there is a nonlinearity in the initial section of the current-voltage characteristic of the diode. This curve "straightens" when the operating point of the rated parameters is reached.

The parameters of the semiconductor device are almost close to ideal. The nonlinearity in the initial section depends on the material from which the crystal is made. Also of great importance is the amount of impurities, that is, the quality of raw materials. The current - voltage characteristic of a semiconductor diode can be represented as a curve that varies approximately exponentially and has an inflection point before it leaves the performance curve. In silicon samples, the operating point "breaks" at a level of 0.6-0.7 Volts. The most close to the ideal value of the current-voltage characteristic of a Schottky diode, here the output point for the performance will be in the region of 0.2-0.4 Volts. But it should be borne in mind that at a voltage of more than 50 volts this property disappears.

The so-called zener diode has a curve, "inverse" to the ordinary element. That is, when the voltage is increased , the current practically does not appear until a certain threshold is reached, after which it increases in an avalanche manner.

Manufacturers of these elements try not to specify the exact characteristics, since they are quite different even within the same batch. In addition, we can take a diode, the VAC of which is accurately measured in the laboratory and change its operating temperature. And the characteristics will change. Usually certain limits of the stable operation of the electronic element are indicated depending on the conditions of its operation.

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