Electronic Engineering 103
SPECIALIST READING A: Transistor Jubilee
11. Scan the text and match the headings (a – j) with the paragraphs (1 – 9). There is one heading you will not need to use.
A) Modern microchips
B) Quality-price ratio
C) Semiconductors
D) The 'magic' a transistor performs
E) Transistor functions
12. Now study the text to find this information and write sentences you have found in the gaps:
_______________________
ability to control _______________________
semiconductance _______________________
_______________________
efforts to find a _______________________
better amplifier _______________________
_______________________ invisible electronic _______________________
device _______________________
_______________________
logic gates _______________________
_______________________
_______________________ quadraphonic hi- _______________________
fidelity sound _______________________
_______________________
reliability of _______________________
transistors in IC _______________________
_______________________
sophisticated _______________________
layering techniques _______________________
transistor can _______________________
control a strong _______________________
current from _______________________
another circuit
Invented at Bell Laboratories in 1947, the transistor resulted from efforts to find a better amplifier and a replacement for mechanical relays. The vacuum tube amplified music and voice during the first half of the 20th century, and it made long-distance calling practical. But it consumed lots of power, operated hot and burned out rapidly. Cheaper to make than the vacuum tube and far more reliable, the transistor cut the cost and improved the quality of phone service.
1. ______________________________
The transistor has many applications, but only two basic functions: switching and modulation. Transistor controls current flow, be it through a lamp or a device to be activated. Both acts as a switch-on/off-and as a modulator/amplifier. The important difference is that the "hand" operating the transistor is millions of times fast. And it's attached to another electrical source – a radio signal in an antenna, for example, a voice in a microphone, or data signal in a computer system, or even another transistor.
2. ______________________________
Transistors are made of semi-conductors such as
silicon and gallium arsenide. These materials carry electricity moderately well – not well enough to be called a conductor, like copper wires; not badly enough to be called an insulator, like a piece of glass. Hence their name is semiconductor. The 'magic' a transistor performs is in its ability to control its own semiconductance, acting like a conductor when needed, or as an insulator when that is needed.
3. ______________________________
Semiconductors differ in the way they act
electrically. Putting a thin piece of semiconductor of one type between two slices of another type has startling results: a little current in the central slice is able to control the flow of the current between the other two. That little current in the middle slice is the juice that is supplied by an antenna or another transistor for example. Even when the input current is weak, as from a radio signal that's traveled a great distance, the transistor can control a strong current from another circuit through itself. In effect, the current through the 'output side' of the transistor mimics the behavior of the current through the 'input side'. The result is a strong, amplified version of the weak radio signal.