How IC works

Integrated circuit chips are the most highly evolved electronic species to date, so to speak.

Integrated circuits evolved from transistors which evolved from radio tubes which evolved from light bulbs. A Canadian engineer discovered the principle of electric amplifiers when they cut the filament of a light bulb, breaking the circuit. A third wire was inserted into the gap. When the voltage between the gap was increased, minute amounts of current in the third wire begin to influence the passage of current through the gap. This was the first radio tube, able to amplify a tiny amount of current - think of the gap as the speaker circuit and the third wire as the antenna circuit. This was the beginning of "wireless" communication and the telegraph was quickly abandoned. Americans then "borrowed" this invention and improved it until voice transmission was possible. This helps to explain why old radio sets are collections of vacuum tubes.

The problem with vacuum tubes is that they are large and consume a lot of electrical power. In the late 1940's an American electrical engineer discovered that tiny germanium crystals could be used like a radio tube. This was the first transistor. Transistors were far smaller than radio tubes and consumed far less power. Transistor radios were small enough to be carried around and became extremely popular in the 1960's.

The first digital computer was constructed in 1940. It was composed entirely of radio tubes and was very large, generated a lot of heat, consumed a lot of power and needed constant repair as the tubes burned out. It was used to instantaneously calculate missle trajectories during world war 2. After the war, the first transistor based computers were used by large businesses. This next generation was smaller and more reliable because of the transistors. However these machines were still very large and also extremely expensive.

Space flight requires an absolute minimum of weight. Flights to the moon demanded computers which were tiny and lightweight. This third generation of computers ran on integrated circuit chips. The chips packed hundreds of individual transistors into a very small space. This was because the transistors were now etched as a pattern onto a silicon wafer. The silicon plate was composed of three layers, each layer etched with a microscopic circuit pattern. Despite the technological sophistication of the process, the three layers still represented the two severed filaments of the light bulb with the third filament in between.

Computer IC's began to be mass manufactured in the 1970's and the price of computers began to decrease. The first popular consumer item based on computer chips was the electronic calculator. It wasn't long before "personal computers" appeared on the market and IC circuits have gotten smaller and more powerful ever since then. Today, computer IC chips are everywhere, functioning as tiny, programmable computers. Such a device is known as an "embedded system".

The IC circuits in a computer are what are known as "flip flops". Several transistors form a circuit which can be turned on or off like a light switch. Eight switches comprise an on/off pattern known as a "byte". The patterns are then used to code binary information inside the computer.

Twenty or thirty transistors can be embedded into a chip which acts like a sort of super amplifier. This is known as an "Operational Amplifier". The circuit calculates the differences in two input voltages and amplifies the result. "Op Amp" chips are probably more important than even computer IC's, since so many circuits can be built with Op Amp chips.

Most modern consumer goods are based on specially designed IC chips particularly suited for a certain application. A good example is a digital alarm clock. Most have a single large chip which keeps track of time, displays the result and is even programmable. Digital music relies on an "Analog to Digital Converter" chip. It takes a digital pattern and generates the electrical waveforms necessary to operate the speakers. "ADC" chips contain hundreds of transistors and if each transistor were a radio tube, the circuit would probably stretch 2 by 4 feet.

I don't precisely know what the next generation of IC's will be like, but the trend continues to be miniaturization. Future IC's may rely on "Quantum effects" as they approach the size of atoms. Quantum mechanics is a branch of subatomic physics which studies the behavior of subatomic particles. This is a very strange environment where particles exist, vanish from our universe and suddenly re-appear elsewhere. Subatomic particles can also exist in more than 1 place at a time. If this bizzare behavior can be turned into something practical, there seems no limit to what future IC circuits will be capable of doing.