MICROELECTRONICS

Thomas Edison's discovery of thermionic emission opened the door to electronic technology. Progress was slow in the beginning, but each year brought new and more amazing discoveries. The development of vacuum tubes soon led to the simple radio. Then more complex systems of communications appeared. Modern systems now allow us to communicate with other parts of the world via satellite. Data is now collected from space by probes without the presence of man because of microelectronic technology.

Sophisticated control systems allow us to operate equipment by remote control in hazardous situations, such as the handling of radioactive materials. We can remotely pilot aircraft from takeoff to landing. We can make course corrections to spacecraft millions of miles from Earth. Space flight, computers, and even video games would not be possible except for the advances made in microelectronics.

The most significant step in modern electronics was the development of the transistor by Bell Laboratories in 1948. This development was to solid-state electronics what the Edison Effect was to the vacuum tube. The solid-state diode and the transistor opened the door to microelectronics.

Microelectronics is defined as that area of technology associated with and applied to the realization of electronic systems made of extremely small electronic parts or elements. The term microelectronics is normally associated with integrated circuits (IC). Microelectronics is often thought to include only integrated circuits. However, many other types of circuits also fall into the microelectronics category. During World War II, the need to reduce the size, weight, and power of military electronic systems became important because of the increased use of these systems. As systems became more complex, their size, weight, and power requirements rapidly increased. The increases finally reached a point that was unacceptable, especially in aircraft and for infantry personnel who carried equipment in combat. These unacceptable factors were the driving force in the development of smaller, lighter, and more efficient electronic circuit components. Such requirements continue to be important factors in the development of new systems, both for military and commercial markets. Military electronic systems, for example, continue to become more highly developed as their capability, reliability, and maintainability is increased.

Millions of people around the world use cellular phones. They are such great gadgets -- with a cell phone, you can talk to anyone on the planet from just about anywhere! These days, cell phones provide an incredible array of functions, and new ones are being added at a breakneck pace. Depending on the cell-phone model, you can store contact information, make task or to-do lists, keep track of appointments and set reminders, use the built-in calculator for simple math, send or receive e-mail, get information (news, entertainment, stock quotes) from the Internet, play games, watch TV, send text messages, integrate other devices such as PDAs, MP3 players and GPS receivers.

But have you ever wondered how a cell phone works? What makes it different from a regular phone? What do all those terms like PCS, GSM, CDMA and TDMA mean? In this article, we will discuss the technology behind cell phones so that you can see how amazing they really are. If you are thinking about buying a cell phone, be sure to check out how a cell phone works and to learn what you should know before making a purchase.

To start with, one of the most interesting things about a cell phone is that it is actually a radio — an extremely sophisticated radio, but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo Marconi). It was only natural that these two great technologies would eventually be combined. On a "complexity per cubic inch" scale, cell phones are some of the most intricate devices people use on a daily basis. Modern digital cell phones can process millions of calculations per second in order to compress and decompress the voice stream. If you take a basic digital cell phone apart, you find that it contains just a few individual parts: an amazing circuit board containing the brains of the phone, an antenna, a liquid crystal display (LCD), a keyboard (not unlike the one you find in a TV remote control), a microphone, a speaker, a battery. The circuit board is the heart of the system.

6. Read and translate the text:

The term 'semiconductor' means half-conductor that is a material whose conductivity ranges between that of conductors and non-conductors or insulators. They include great variety of elements (silicon, germanium, selenium, phosphorus and others), many chemical compounds (oxides, sulphides) as well as numerous ores and minerals.

While the conductivity of metals is very little influenced by temperature, conductivity of semiconductors sharply increases with heating and falls with cooling. This dependence has opened great prospects for employing semiconductors in measuring techniques.

Light as well as heat, increases the conductivity of semiconducting materials, this principle being used in creating photo resistances. It is also widely applied for switching on engines, for counting on conveyer belts, a well as various systems of emergency signals and for reproducing sound in cinematography. Besides reacting to light, semiconductors react to all kinds of radiations and they are therefore employing in designing electronic counters.

Engineers and physicists turned their attention to semiconductors more that fifty years ago, seeing in them the way of solving complicated engineering problems. Converting heat into electricity without using boilers or other machines was one of them. This could be done as means of metal thermocouples, but in this way impossible to convert more one per cent of the heat into electricity. The thermocouples made later of conductors more generated ten times as much electricity as the metal ones.

Sunlight like heat can feed our electric circuit. Photocells made of semiconducting materials are capable of transforming ten per cent of sunray energy into electric power. By burning wood, which has accumulated the same amount of solar energy, we obtained only heat fractions of one per cent of electric power. The electricity generated by semiconductor thermocouples can produce not only heat but also cold, this principle being used in manufacturing refrigerators. Semiconducting materials are also excellent means of maintaining a constant temperature irrespective of the surrounding temperature changes. The latter can vary over a wide range, for example, from 59C below OC to 100C above OC. Semiconductors are the youngest field of physical science. Yet even now they are determining the process of radio engineering, automation, chemistry, electrical engineering and many other fields of science and technique.

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