What is the transistor in the electrical circuit. Principle of operation of the transistor, internal device and the main characteristics of transistors. What do you need transistors

Any electronic device consists of radio elements. They can be passive that do not require a power source, and active whose work is possible only when the voltage is applied. The active elements are called semiconductors. One of the most important semiconductor devices is the transistor. This radio element came to replace the lamp devices and completely changed the circuitry of the devices. All microelectronics and operation of any chip based on it.

The TRANSISTOR name occurred from the confluence of two English words: Transfer - portable, and resistor - resistance. In the generally accepted concept, this is a semiconductor element with three conclusions. In it, the current value on two conclusions depends on the third, when the current or voltage changes, the current circuit current is controlled. The current variation is controlled by bipolar devices, and the voltage is field.

The first developments of the transistor were started in the XX century. In Germany, scientist Julius Edgar Lilienfeld described the principle of operation of the transistor, and already in 1934 the instrument named after the transistor was registered with physician Oskar Hale. Such a device worked on the electrostatic field effect.

Physics William Shockli, Walter Bratsky, along with John Bardin, at the end of the 40s, made the first layout of the point transistor. With the opening of the N-P of the transition, the release of the point transistor stopped, and instead it began to develop plane devices from Germany. The acting prototype of the transistor in December 1947 was officially presented. On this day, the first bipolar transistor appeared. In the summer of 1948, devices performed on a transistor basis began to be sold. From this point on, the electronic lamps (triododes) are common at that time began to go into the past.

In the mid-50s, the first plane transistor was released into a series of Texas Instruments, silicon served as a material for its manufacture. At that time, a lot of marriage was published during the production of the radio element, but this did not prevent the technological development of the device. In 1953, a scheme used in hearing aids was made on the transistors, and a year later, American physicists received a Nobel Prize for their discovery.

March 1959 was marked by the creation of the first silicon planar device, his developer was a physicist from Switzerland Jean Ernie. A pair of transistors was successfully placed on a single silicon crystal. From now on, the development of integrated circuit equipment has begun. To date, one billion transistors are placed in one crystal. For example, on the popular 8-nuclear computer processor Core i7-5960x, their number is 2.6 billion pieces.

In parallel with the improvements of the bipolar transistor in the 60s, the development of an instrument based on a metal compound with a semiconductor began. Such a radio element was called the MIS (metal-oxide-semiconductor) transistor, today is a better known under the designation "Mosfet".

Initially, the concept of "transistor" was referred to resistance, the value of which was controlled by voltage, since the transistor can be represented as a resistor regulated by the attached potential in one output. For field transistors, a comparison with which is more correct - the potential on the gate, and for bipolar transistors - the potential based on or current base.

The basis of the operation of the device consists in the ability of the N-P of the transition to skip the current one way. When the voltage is applied in one transition there is a direct drop, and on the other inverse. The direct voltage transition zone has low resistance, and with the reverse - large. A small control current flows between the base and emitter. The resistance between the collector and the emitter changes from the value of this current. The bipolar device is two types:

• p-N-P;
• n-P-N.

The difference lies only in the main charge carriers, i.e. the current direction.

If you connect two semiconductors of different types of each other, then on the border of the connection there is an area or, as is customary, P-N transition. The type of conductivity depends on the atomic structure of the material, namely how strong communication in the material. Atoms in the semiconductor are located in the form of a lattice, and this material itself is not a conductor. But if you add atoms of another material in the grid, then the physical properties of the semiconductor change. The noted atoms are formed, depending on their nature, free electrons or holes.

Formed free electrons form a negative charge, and the holes are positive. In the transition area there is a potential barrier. It is formed by the contact difference of potentials, and its height does not exceed the tenths of the volt, preventing the flow of charge carriers deep into the material. If the transition is under direct voltage, then the magnitude of the potential barrier decreases, and the value of current passing through it increases. When applying the reverse voltage, the barrier value increases and the resistance of the barrier of the current increases. Understanding the work of the P-N of the transition, you can figure out how the transistor is arranged.

First of all, such devices are divided into single and composite. There are also so-called complex radio elements. They have three conclusions and are made, as a whole. Such assemblies contain both the same type and different transistors in their type. The main separation of devices occurs on the following features:

The general definition for the radio element can be formulated as follows: The transistor is a semiconductor element designed to convert electrical values. The main application is to enhance the signal or work in key mode.

The principle of operation of the transistor for the kettle is easier to describe by analogy with the water supply. The element itself can be represented as a valve. Crane with a small turn allows you to adjust the flow of water (current strength). If you turn a little handle, the water flows through the pipe (conductor), if you open the tap even more, the water flow will also increase. Thus, the water flow output is proportional to its input multiplied by a certain amount. This magnitude is the gain coefficient.

The bipolar transistor has three outputs: Emitter, base, collector. The emitter and collector have the same type of conductivity, which is different from the base. A hole-type transistors consist of two regions P-type conductivity, and one N -typ. Electronic type on the contrary. Each area has its own conclusion.

When the signal is applied to the emitter, the current conductivity current in the base area increases. The main charge carriers move to the base zone, which leads to an increase in current and in the back of the connection. There is a volume charge. The electrical field begins to pull into the reverse connection zone media of another sign. In the database, partial recombination (destruction) of the charges of the opposite sign occurs, due to which the current of the base occurs.

The emitter is called the area of \u200b\u200bthe device that serves to transmit charge carriers to the base. The collector is called a zone designed to extract charge carriers from the base. And the base is the area for transmitting the emitter of the opposite amount of charge. The main characteristic of the device is a volt-ampere characteristic, the function of which describes the relationship between the current and voltage.

On the diagram, the device is signed by Latin letters VT or Q. It looks like a circle with an arrow inside, where the arrow indicates the direction of flow flow. For PNP (direct conductivity) - an arrow inside, and NPN (reverse conductivity) - an arrow outward. In order to make a transistor, germanium or silicon is used. These materials are distinguished by the working area of \u200b\u200bthe basic transition voltage. For Germany, it lies in the range of 0.1-0.4 V, and silicon is commonly used for silicon from 0.4 to 1.2 V..

The difference in the field transistor from bipolar is that in it for the passage of the current corresponds to the voltage value attached to the controlled contact.

The main purpose of mosfets is associated with their good switching speed with a very small power applied to the control. Field element has three outputs: shutter, stock, source. When the mosfet with the control of N-p, the transition potential on the gate is either zero (the device is open), or has a definite value greater than zero (the device is closed). When the reverse voltage reaches a certain level, the locking layer opens, and the device switches to the cutoff mode.

In the Mosphore with P-N, the transition control electrode (shutter) serves as a semiconductor layer having a p-type conductivity, and the opposite conductivity is the N-type channel.

Its image in the diagram is similar to a bipolar device, only all lines are performed straight, and the arrow inside emphasizes the type of instrument. The principle of operation of the MOS of devices is based on the effect of changes in the conductivity of the semiconductor at the boundary of the region with a dielectric when exposed to an electric field. Field devices depending on the controlled P-n of the transition can be:

Each view can have a conductivity of both p-type and n-type. In general understanding, the principle of operation does not depend on the conductivity, only the polarity of the voltage source changes.

The transistor is a complex device, physical processes passing in which are complex to understand beginner radio amateurs (teapots). As the transistor works, it can be explained as follows: the transistor is an electronic key, the degree of opening of which depends on the level of current or voltage applied to its controlled output (base or shutter).

Why do you need a transistor, you can describe in a generalized form. For example, the base (shutter) of the device is the door. It opens by external influence, i.e. the voltage of the same polarity as the collector (source). The greater the voltage, the door will open more. Before the door, there is a turn of people (charge carriers) who want to run through it (collector-emitter or source-stock). The more impact on the door, the more it is open, and therefore people run more.

Therefore, representing the door in the form of a resistance of the transition, we can conclude: the more impact on the base (shutter), the smaller the resistance to the main charge carriers (people) in the case of direct polarity. If the polarity changes (the door closes on the castle), then there will be no movement of charges (people).

This is such a tricky figovin, transmitting a current only one way. It can be compared with the nipple. It is used, for example, in rectifiers, when the alternating current is constant. Or when it is necessary to separate the reverse voltage from the direct. Look at the programmer scheme (where there was an example with a divider). You see diodes stand, as you think, why? And everything is simple. In a microcontroller, logical levels are 0 and 5 volts, and Som port is a minus 12 volts, and zero plus 12 volts. Here is a diode and cuts this minus 12, forming 0 volts. And since the diode in the direct direction the conductivity is not perfect (it generally depends on the applied direct voltage than it is more, the better the diode conducts the current), then approximately 0.5-0.7 volts will fall at its resistance, the residue, being divorious resistors, will be approximately 5.5 volts, which does not go beyond the limits of the controller.
The conclusions of the diode are called the anode and cathode. Current flows from the anode to the cathode. Remember where what conclusion is very simple: on the conditional designation the arrogant and a stick from the side toatoda as if painting the letter TO here look - TO| -. K \u003d cathode! And the cathode details are indicated by a strip or point.

There is another interesting type of diode - stabilirton. His I use in one of the past articles. Its feature is that in the forward direction it works as an ordinary diode, but in the opposite it breaks on any voltage, for example, by 3.3 volts. Like the restrictive valve of the steam boiler, which opens when the pressure is exceeded and the steam streaming. Stabilians use when they want to obtain the voltage of a given value, regardless of the input voltages. This may be, for example, a reference value relative to which there is a comparison of the input signal. They can trim the incoming signal to the desired value or use it as protection. In my schemes, I often put a stabilion on the nutrition of the controller to 5.5 volts, so that in the case of which if the voltage will sharply jump, this stabilion was stated through himself excess. There is also such a beast as a suppressor. The same stabilion, only much more powerful and often bidirectional. Used to protect power.

Transistor.

A terrible thing, in childhood everything could not understand how he works, but it turned out to be simple.
In general, the transistor can be compared with a controlled valve, where we control the most gluable stream. Slightly turned the handle and the tons of shit were smelled along the pipes, opened the rather and now everything around choking in unclean. Those. The output is proportional to the input multiplied to some value. This magnitude is amplification coefficient.
These devices are divided into field and bipolar.
In bipolar transistor there emitter, collector and base (see the conditional design). Emitter he with the arrow, the base is indicated as a direct area between the emitter and the collector. Between the emitter and the collector, there is a high current of payload, the current direction is determined by the arrow on the emitter. But between the base and emitter there is a small control current. Roughly speaking, the magnitude of the control current affects the resistance between the collector and the emitter. Bipolar transistors are two types: p-N-P and n-P-N The principal difference is only in the direction of the current through them.

The field transistor differs from bipolar because it resistance to the channel between the source and the drain is no longer determined by the current, but the voltage on the gate. Recently, field transistors have received huge popularity (all microprocessors are built on them), because The currents in them proceed microscopic, the crucial role plays the tension, which means that the loss and heat dissipation are minimal.

In short, the transistor will allow you a weak signal, for example, from the foot of the microcontroller ,. If there is not enough strengthening of one transistor, they can be connected by cascades - one by one, all powerful and powerful. And sometimes enough and one mighty field MOSFET. transistor. Look, for example, as in the diagrams of cell phones, the vibrating alert is controlled. There, the exit from the processor goes to the valve of power MOSFET. key

The transistor, otherwise called semiconductor trigode - an electronic device, the basis of which are semiconductor materials. The main purpose of the device is the possibility, by changing the weak current in the control circuit, to obtain a reinforced signal at the output. Semiconductor triode is one of the main components of the sets of multiple electronic devices, from the radio to the computer.

The definition of the Transistor is closely related to the etymology of this word. It is formed from two English words: TRANSFER (transfer) and Resistor (resistance). Indeed, the principle of operation of the device is associated with the transfer (change) of resistance in the electrical circuit.

• bipolar;
• field (unipolar).

Each class, in turn, is divided into several varieties.

Bipolar:

Both of these types of triododes can be used in one electronic circuit. Therefore, in order not to confuse, which item should be used in a particular location of the scheme, the images P-N-P and N-P-N triododes differ from each other.

Field:

• unipolar with P-N transition;
• TIR transistors with an isolated shutter.

Principle of operation of the device

In electronics, semiconductors are used from electron (N) or hole (P) conductivity. These designations suggest that in the first case, negatively charged electrons prevail in the semiconductor, in the second - positively charged holes.

Consider how the transistor is arranged on the example of a bipolar semiconductor trigger. Externally, the device looks like a small part in a metal or plastic case with three conclusions. Inside - a peculiar sandwich of the three semiconductor layers. If the central layer of p-type, then the layers surrounding it is n-type. It turns out triode N-P-N. If the center is also referred to as the base, n-type, then the plates are from a semiconductor with hole conductivity, and the structure of the device is p-n-p. One of the external layers is called the emitter, another collector. Each of these three parts of the instrument is the appropriate conclusion.

A brief explanation, as the transistor works, for "kettles" looks like this. Take for example the N-P-N transistor, where the emitter and collector are layers with preferably electronic conductivity, and the base with hole.

We connect the emitter to the negative output of the electrical battery, and the base and collector to the positive one. A beginner lover of electronics can be represented that triode consists of two diodesWhile the Emitter diode is the base is in the forward direction, and the current flows through it, and the diode base is turned on in the opposite direction, and there is no current.

Suppose that we have included a variable resistor in the base chain, with which we can adjust the voltage supplied to the database. What effect do we get with a decrease in voltage to zero? The current in the Emitter-Base chain will no longer flow. I will increase the voltage slightly. Electrons from N - Emitter region will rush to the database connected to the plus of the battery.

Important detail - the base is made as thin. Therefore, the mass of electrons passes this layer through and turns out to be in the collector under the influence of the positive pole of the battery to which it is attracted. Thus, the current begins to pass not only between the emitter and the base, but also between the emitter and the collector. At the same time, the collector current is much larger than the current base.

Another important circumstance: A small change in the base current causes a significantly stronger change in collector current. Thus, semiconductor triode is used to enhance various signals. Usually bipolar triododes are more often used in analog technology.

Field transistors

This type of trigger differs from bipolar non-properties or functions, but the principle of work. In the field trifle, the current moves from the output, called the source, to the conclusion, referred to as the flow, according to the semiconductor of one type of conductivity, for example, p. And the control of this current is performed by changing the voltage in the third pin - the gate.

Such a structure more accurately meets the requirements of modern digital technology, where field triodes are mainly used. Today's technological capabilities allow you to place a semiconductor area of \u200b\u200b1-2 square centimeters on a semiconductor crystal of several billion TIR elements with an isolated shutter. Thus, the central processors of personal computers are created.

Prospects for the development of devices

Prospects lie, first of all, in the field of further miniaturization of devices. So, American scientists develop today the so-called one-molecular transistor. The main element of such a device is the benzene molecule to which three electrodes are attached.

If the idea justifies itself, the possibility of creating heavy duty computing complexes will appear. After all, the size of the molecule is much smaller than the size of today's TIR-triodes on a silicon chip crystal.

Transistors underlie most electronic devices. It can be in the form of individual radio components, or in the composition of the chip. Even the most complex microprocessor consists of a great set of tiny transistors, tightly placed in its mighty crystal.

Transistors are different:
Two main groups are bipolar and field. The bipolar transistor is indicated in the diagram, since it is shown in Figure 1. It can be straight (p-p-p) and reverse (P-P-P) conductivity. The structure of the transistor, and the physical processes that occur in it are studied at school, so we will not talk about it, "so to speak, closer to practice. In essence, the difference is that the transistors are plugged in such a way that the positive potential of the accomplice proceeds to their emitter, and the collector is negative. For transistors N-P-P - the opposite, the emitter gives a negative potential to the collector - positive.

Why do you need a transistor?
It is mainly used to enhance current, signals, voltages. And the gain occurs due to the power source. I will try to explain the principle of work "on the fingers". In the car there is a vacuum brake amplifier. When the driver presses the brake pedal, its membrane moves and the valve opens through which the engine engine sucks this membrane by adding it an effort. As a result, the weak force of pressure on the brake pedal leads to a strong effort on brake pads. And the additive of force occurs due to the power of the machine working motor.

So with the transistor it seems. The base is fed by a weak current (Fig. 2). Under the action of this current, the conduction collector - the emitter increases and a much stronger current coming from the power supply is already flowing through the collector. Weak database current changes, - a strong collector current changes accordingly. Ideally, a graph of the collector current changes looks like a magnified copy of the change in the database current.
This difference between the weak current of the base and the strong current of the collector is called the gain of the current transistor, and is indicated by and21. It is determined like this: H21E \u003d IK / I6 (collector current to divide the base current). The greater this parameter, the better the amplifying properties of the transistor.
But it's all ideally. In fact, the dependence of the current collector from voltage on the basis is not so linear. It should be remembered by the BAX diode, where at the bottom of the current characteristics is very small, and it starts to sharply increase when the voltage reaches a certain value. Since the transistor is based on the same physical processes, then there is a similar "defect".

If we collect the amplifier scheme shown in Figure 3, and we will talk to the microphone, there will be no sound in the dynamics. Because the voltage on the microphone is very small, it is below the transistor opening threshold. Here, not only there is no amplification, but even on the contrary, there will be a weakening of the signal.

So that the transistor earned as an amplifier to increase the voltage at its base. This can be done in some way increasing the voltage at the microphone output. But then the meaning of the amplifier is lost. Or must be submitted to the transistor base some constant voltage (Fig. 4) through the resistor, so that the transistor is to open. And the weak alternating voltage is submitted to the database of this transistor through the capacitor. Now the most important thing is the weak alternating voltage with constant voltage based on the database. The stress on the base will change to the tact of weak variable voltage. But since the constant voltage displaced the operating point of the transistor on a steep linear section of the characteristics, the gain occurs.
Simply put, the weak voltage had no strength to open the transistor, and we added to help a constant voltage, which opened the transistor.

A constant voltage that is fed to the transistor database to shift its operation mode into a plot with a coolest and linear characteristic is called a bias voltage. By changing this voltage, we can even adjust the gain of the amplifying cascade.

Transistors are not always used with a bias voltage. For example, in the amplifying cascades of transmitters, the bias voltage to the transistors can not be applied, since the amplitudes of the input voltage is quite enough for the "roll" of the transistor.

If the transistor is not used as an amplifier, but as a key, the bias voltage also does not allow the database. Simply, when the key must be closed, - the stress on the base is zero, and when it should be open, the database voltage is sufficient to open the transistor. It is usually used in digital electronics, where there is only zeros (no voltage) and units (there is voltage) and no intermediate values.

Figure 5 shows a practical scheme to make a computer column from the reproducer. You need a simple single-software reproducer with only one fork for connecting to a radio network (multi-program has a second plug for the power grid). No changes in the scheme of the reproducer do not need. It connects to the transistor collector as well as the radio network.

Inside the single-software reproducer there is a speaker, a variable resistor for adjusting the volume and transformer. All this is necessary, and it remains. When you open the reproducer case, refractive the collector of the transistor and plus the power source to the places to which its wire with a fork. The wire itself can be removed.

To connect to a computer, you need shielded wire with the corresponding plug at the end. Or the usual two-wire wire. If the wire is shielded, connect the braid to the emitter of the transistor, and the central core to the C1 condenser.
The signal from the computer sound card is fed through the plug to the C1 condenser. Power supply is supplied from the power supply unit. The power supply unit from the game console to TV, type "Dandy", Kenga is suitable. Generally suitable any power supply with a voltage at the outlet from 7V to 12V. To connect to the power unit, the corresponding socket will be required, it must be installed on the reproductory housing, drill a hole for it. Although, of course, you can feed the wires from the power supply and directly to the diagram. Connecting the power supply must be observed by polarity. The VD1 diode is not needed in principle, but it protects the scheme from failure if you confuse plus with a minus at the power supply. Without it, with the wrong power connection, the transistor can be burned, and with a diode, if the poles of the power supply is confused, simply will not turn on.

The CT315 transistor in a rectangular case, which has a bevel on one side (shown in the figure). Now, if you turn it from myself, and the conclusions up, then the bottom will be the base, to the right emitter, and the collector in the middle. CT315 transistor is suitable with any letter (CT315A, CT315B ...). The transistor needs to be secured correctly, without confusing its conclusions. If you are wrong and turn on the power it can die. Therefore, after all spikes do not be lazy to check the correct installation, whether the conveyor, capacitors, diodes are proposed correctly. And only when you are 100% confident, - turn on.

Diode VD1 type KD209. It has an anode. You can also put another diode, for example, 1N4004 or some more. If the diode is imparted incorrectly the scheme will not work. So, if all turned on, but does not work, start checking the correctness of the diode connection.

Capacitors are electrolytic, no less than 12V voltage. Our K50-16, K50-35 or imported analogs are suitable. It should be noted that our capacitors on the housing are plus near the positive conclusion, and imported minus or a wide vertical strip in negative output. Instead of a 10 μF capacitor, you can choose to any capacity from 2 μF to 20 μF. Instead of a capacitor at 100 μF, a capacitor of any capacity of at least 100 μF is suitable.

In Figure below, the circuit shows the mounting scheme, on it the places of the packs are marked with points. Do not confuse the places of paks with the intersection of wires. Installation is made by attachment, using parts and mounting wiring. It is advisable to put the entire scheme inside the enclosure of the reproducer (there is usually a lot of space there).

If everything works, but a strongly phonite, "it means that you confused the wires going to the sound card. Change them in places.

Putting the scheme from the computer power source should not be!

For the stereard, you can make two speakers, inputs combining into one stereo cable to connect to the sound card, well, and save both columns from one power supply.

With one transistor cascade, the column will sound quietly, but enough for listening in a small room. The volume can be adjusted both the computer regulator and the handle that there is a reproducer.

What does the name "transistor" mean

The transistor did not immediately receive such a familiar name. Initially, by analogy with the lamp technique it was called semiconductor triode. The current name consists of two words. The first word is "Transfer", (here immediately remembers the "transformer") means the transmitter, the converter, the carrier. And the second half of the word resembles the word "resistor" - part of the electrical circuits, the main property of which electrical resistance.

This resistance is found in the law of Ohm and many other formulas of electrical engineering. Therefore, the word "transistor" can be expanded as a resistance converter. Approximately the same as in the hydraulics, the change in fluid flow is regulated by the valve. The transistor has such a "valve" changes the number of electrical charges that create an electric current. This change is nothing but a change in the internal resistance of the semiconductor device.

Strengthening electrical signals

The most common operation that is performed transistors, is an strengthening electrical signals. But this is not a completely true expression, because weak signal from the microphone is also remained.

Strengthening is also required in radio and television: a weak signal from an antenna with a capacity of billion dollars of watt must be strengthened to such an extent to get a sound or image on the screen. And this is already a power of several dozen, and in some cases hundreds of watts. Therefore, the gain process is reduced to ensure that with the help of additional sources of energy obtained from the power supply, get a powerful copy of a weak input signal. In other words, low-power input impact controls powerful energy streams.

Strengthening in other areas of technology and nature

Such examples can be found not only in electrical circuits. For example, when the gas pedal is pressed, the vehicle speed increases. At the same time, to press the gas pedal, it is not very strong - compared with the power of the engine, the power of pressing the pedal is negligible. To reduce the speed, the pedal will have to go somewhat, weaken the input effect. In this situation, gasoline is a powerful energy source.

The same impact can be observed in hydraulics: to open the electromagnetic valve, for example, in the machine, energy, is quite a bit. And the oil pressure on the piston of the mechanism is able to create a force of several tons. This effort can be adjusted if in the oil pipeline to provide adjustable valve as in the usual kitchen crane. Slightly covered - the pressure fell, the effort decreased. If you opened more, then the pressure intensified.

On the turn of the valve, too, no particular effort is required. In this case, the external source of energy is the pumping station of the machine. And similar impacts in nature and technique you can see the great set. But still, we are more interested in the transistor, so you will have to consider ...

Electric signal amplifiers