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Inhaltsverzeichnis

Frontmatter

1. Conductors, insulators and semiconductors

Abstract
Electrical materials are usually classified into three groups according to their electrical conductivity. Materials having a high electrical conductivity are termed good conductors and are usually metals. Materials which are poor conductors of electricity are called insulators. The third group consists of materials whose conductivities lie between those of metals and insulators. These materials which are called semiconductors play an important role in the field of electronics.
Ariacutty Jayendran, Rajah Jayendran

2. Semiconductors

Abstract
Semiconductor materials used in electronic devices need to have a very high degree of purity and these highly purified semiconductors are called intrinsic semiconductors.
Ariacutty Jayendran, Rajah Jayendran

3. The junction diode

Abstract
A p-n junction can be formed in a semiconductor crystal by introducing donor impurities into one part of the crystal and acceptor impurities into the other part of the crystal. A junction is formed in the region where the two types of impurities meet. A junction diode is constructed by attaching two ohmic metallic contacts to the ends of a semiconductor crystal which has a sharp p-n junction inside it. Such a device behaves like a rectifier allowing a large current to flow in one direction, and a negligible current to flow in the other direction.
Ariacutty Jayendran, Rajah Jayendran

4. Other types of semiconductor diodes

Abstract
The junction formed between a metal and a semiconductor can be either an ohmic junction or a rectifying junction. The leads or external contacts of a semiconductor device must under normal conditions form ohmic or nonrectifying junctions with the semiconductor. The junction between a metal and a semiconductor inside a metal-semiconductor diode must however, be a rectifying one. Such a diode is often called a Schottky diode. The external voltage-current characteristic curve of a Schottky diode is similar to that of a junction diode, but the physical mechanisms involved in the conduction process are more complicated.
Ariacutty Jayendran, Rajah Jayendran

5. The junction transistor

Abstract
The junction transistor consists of three semiconductor regions with two sharp junctions between them. The regions are arranged in the order npn or pnp, and are called emitter, base, and collector. The two possible types of transistor are shown in Fig 5.1 with their circuit symbols. The central region is very narrow in width, and has a much lower impurity concentration than the two outer regions.
Ariacutty Jayendran, Rajah Jayendran

6. The basic amplifying action of a transistor

Abstract
The transistor is widely used as an amplifying device, and can provide voltage gain, current gain, and power gain. The basic amplifying action may be understood by considering the circuit of Fig 6.1. This circuit is known as the common base circuit due to the fact that the base terminal is common to both input and output circuits.
Ariacutty Jayendran, Rajah Jayendran

7. Transistor characteristics and the operating point

Abstract
When a transistor is used in a circuit, the D.C operating conditions have to be first optimized so that the transistor will operate as linearly as possible. It is desirable that the largest possible output voltage be produced with the minimum of distortion. The optimization of the D.C operating conditions is done by a graphical method which uses two families of characteristic curves called the input and output characteristics.
Ariacutty Jayendran, Rajah Jayendran

8. Transistor equivalent circuits

Abstract
The first step in designing a transistor amplifier stage is to establish the D.C operating conditions by using a graphical method as shown in the last chapter. After this has been done, small signals which are applied to the input of a transistor circuit will be amplified with reasonable linearity.
Ariacutty Jayendran, Rajah Jayendran

9. The frequency response of a transistor amplifier

Abstract
Wideband amplifiers can amplify over a wide band of frequencies from a few hertz to several megahertz. A typical example of such an amplifier is the video amplifier in a television receiver. A nonsinusoidal input signal is composed of many frequencies, and if the output is to be an exact replica of the input, then the following conditions must be satisfied.
Ariacutty Jayendran, Rajah Jayendran

10. The transistor at high frequencies

Abstract
The currents flowing through a transistor arise from the flow of charge carriers between the different regions of the transistor.This process takes time and the response of the transistor to changes in input voltages and currents is not instantaneous. The result is that there is a gradual decrease of the short-circuit current gain parameter at high frequencies. The equivalent circuit used to represent the high frequency behaviour of a transistor has therefore to be different from the circuit used at low frequencies.
Ariacutty Jayendran, Rajah Jayendran

11. Feedback amplifiers

Abstract
The characteristics of an amplifier can be modified and improved considerably by the use of negative feedback. In this process a part of the output signal is combined with the input signal. If the output signal increases in magnitude, then the effect of the negative feedback signal is such that it opposes the increase in the output signal.
Ariacutty Jayendran, Rajah Jayendran

12. Operational amplifiers

Abstract
The operational amplifier in integrated circuit form has been widely used as a building block in analog circuits. It has the advantages of versatility, reliability, small size, low cost, and the ability to amplify D.C signals.
Ariacutty Jayendran, Rajah Jayendran

13. Linear analog systems

Abstract
The integrated circuit (IC) operational amplifier has been used as a building block in the construction of a variety of linear and nonlinear analog systems.
Ariacutty Jayendran, Rajah Jayendran

14. The field effect transistor

Abstract
The operation of the junction transistor depends on the flow of both majority and minority charge carriers. The other widely used type of transistor is the field effect transistor whose operation depends only on the flow of majority carriers. The field effect transistor is therefore called a unipolar device.
Ariacutty Jayendran, Rajah Jayendran

15. Oscillators and signal generators

Abstract
A large variety of circuits and instruments have been developed for the generation of periodic and nonperiodic signals. Different types and shapes of signals are required for different purposes. For example the carrier waveform generated by the quartz oscillator in a TV transmitter is very different from the waveform produced by the time-base generator in a TV receiver.
Ariacutty Jayendran, Rajah Jayendran

16. Silicon controlled rectifiers or thyristors

Abstract
Solid state devices play an important part in electrical power control, particularly in applications which require a variable but controlled amount of current. Among these are motor speed control, electrical welding, and lighting control. The use of silicon controlled rectifiers has made electrical power control an efficient and inexpensive process.
Ariacutty Jayendran, Rajah Jayendran

17. Logic circuits

Abstract
Logic circuits form the basis of a large number of electronic systems like computers, data processing systems, and digital communication systems. Digital systems possess many advantages over analog systems and there is an increasing trend towards converting analog signals into digital signals and then using digital systems to process the signals further.
Ariacutty Jayendran, Rajah Jayendran

18. Logic families

Abstract
Many types of electronic circuits have been used to implement logic gates. These are almost invariably manufactured in the form of integrated circuits. The integrated circuits used are classified into logic families depending on the type of circuits used for the gates. Among the families are:
  • DTL Diode Transistor Logic
  • TTL Transistor Transistor Logic
  • ECL Emitter Coupled Logic
  • CMOS Complementary MOS Logic
Ariacutty Jayendran, Rajah Jayendran

19. Flip-flops

Abstract
A digital system needs memory elements to store digital information. One type of memory element is the bistable multivibrator commonly called a latch. A latch is an electronic device that has two stable states. It remains indefinitely in one of these states until it is triggered into the other state.
Ariacutty Jayendran, Rajah Jayendran

20. Shift registers

Abstract
A flip-flop can store a single binary digit. The storage of a number of binary digits can be accomplished by combining a number of flip-flops to form a device called a shift register. The name shift register originates from the fact that this device takes in one new digit for each clock pulse while at the same time shifting the existing digits by one stage to make room for the new digit.
Ariacutty Jayendran, Rajah Jayendran

21. Electronic counters

Abstract
Electronic counters are widely used in instruments, computers, and other digital systems. The availability of counters in IC form has made electronic counting a reliable and inexpensive process. Electronic counters usually use the binary system, but the binary output can easily be converted into decimal or other form, by the use of suitable converting circuits. Both binary and decimal counters are available as IC chips. The basic element of the binary counter is the master-slave flip-flop set to toggle or reverse its state on each clock pulse.
Ariacutty Jayendran, Rajah Jayendran

22. Semiconductor memories

Abstract
In almost all computer and data processing systems it is necessary to be able to store information and retrieve it when required. The storage unit or memory is one of the most active parts of a computer. It stores the program, the input data, and also the processed data, at various stages of the computing process. A computer memory has many thousands of registers, each register storing a word, where a word consists of a number of bits. Virtually all of the memories in use today are of the semiconductor type.
Ariacutty Jayendran, Rajah Jayendran

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