MODERN ELECTRONICS

The study of semiconductor devices is an essential part of modern science, which is called electronics. This science studies the properties and laws of motion of electrons, as well as the laws of the transformation of various types of energy through electrons. On the basis of the laws of motion of electrons, devices have been created that are used in the widest possible way in various fields of science, technology, and in everyday life, in various devices, apparatus, and machines. Radio engineering is one of the fields of application of electronics and the devices it has created - electrovacuum, semiconductor, molecular and quantum.

Electrovacuum devices are based on the use of the motion of free electrons and ions in a vacuum or in rarefied gases under the influence of electric and magnetic fields. These devices serve as the basis for the creation of the vast majority of types of electronic equipment; they are especially important in the development of powerful radio communication devices, television, radar, radio navigation and other means of radio electronics.

In turn, electrovacuum devices are divided into two main classes: electronic and ionic devices. Electronic devices in which the motion of electrons occurs in vacuum with a high degree of gas evacuation ( ^10–7 mmHg and below) are characterized by high electron velocities and are suitable for generating and amplifying coli *** in wide radio frequency bands. In everyday life, they are called radio tubes. Ionic (otherwise gas-discharge) devices contain gas (at a pressure of 10 ^-3 mm Hg. Art. And above), and therefore electrons moving in them are likely to collide with gas molecules, produce their ionization, and take part in the working process electrons, but also ions. Such devices are used in electric power industry, especially in AC-to-DC converters (rectifiers), as well as in automation and radio-electronic devices as the basis of automatic switching circuits, etc. The principles of operation of electronic and ion devices, we will consider separately.

Semiconductor devices are based on the movement and distribution of charges under the influence of electric and magnetic fields inside crystals of a solid. Such devices not only can replace radio tubes in many cases, but also open up new possibilities for the use of radio electronics in a number of branches of the national economy. Especially important was the use of semiconductor devices in those installations that consist of tens of thousands of active elements (for example, electronic computers): semiconductor devices can reduce the size (miniaturize) and increase the time of reliable operation of equipment.

Molecular electronics is the most progressive direction in miniaturization of equipment. This direction involves the creation of radio circuits in a solid, i.e. further development of semiconductor technology. With the help of certain impurities, zones of different electrical properties that form the functions of resistances, capacitors, semiconductor devices, etc. are formed in the crystalline body. The combination of these zones forms an electronic circuit in a semiconductor chip. The devices created on the basis of molecular electronics are extremely small in size and are the highest achievement in the field of microminiaturization of radioelectronic equipment.

Quantum electronics is based on the latest achievements of physics in the study of quantum phenomena occurring inside atoms and molecules of matter in the solid, gaseous and liquid state. Quantum generators of different types emit electromagnetic waves in different ranges, in particular, waves can be about a micron in length, i.e. in the region of the visible (light) and infrared spectra. Such generators create almost parallel light beams of enormous brightness, which makes it possible to concentrate colossal energy in small volumes. These generators can find a variety of applications, including in space technology.

Within the framework of the book "Fundamentals of Radio Engineering", it is possible to present only those sections of electronics that are directly related to the tasks of generation, amplification and conversion of radio frequency and sound frequency colo; The specifics of electronic computing equipment and apparatus for radiation of waves of the light and near-light ranges are considered in the specialized books, respectively. Therefore, this chapter is devoted to electrovacuum, semiconductor and ion devices and only briefly introduces the reader to other problems of electronics.