Download Class: G3a/b Topic: Bipolar transistors – part 1

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Disciplinary literacy development: Electrical Engineering (LAV) and English (ANG)
Class: G3a/b
Topic: Bipolar transistors – part 1
Task 1 LISTENING COMPREHENSION
Watch the video on semiconductor research and complete the sentences by choosing the best answer
according to the video.
1. The _____ caused research on semiconductors to increase significantly.
a) space race
b) Second World War
c) growing popularity of silicon
2. Semiconductors made from silicon replaced ____ in the improved British radar technology.
a) valves
b) capacitors
c) chips
3. Early amplifiers used ____ to increase the strength of signals.
a) germanium chips
b) transformers
c) vacuum tubes
4. The first working model of an amplifier using semiconductors was built by ____.
a) Bell Labs
b) German scientists Herbert Mataré and Heinrich Welker
c) The Bose company
5. Semiconductors were preferred to valves or vaccum tubes because:
a) semiconductor technology was much simpler than the technology in vaccum tubes
b) semiconductors were smaller and cheaper
c) vacuum tubes could not be mass-produced
6. The term transistor was introduced by ____.
a) Bell Labs
b) Herbert Mataré and Heinrich Welker
c) The Bose Company
Read the text on bipolar transistors and complete the tasks that follow.
Bipolar Transistors
A transistor is made of a solid piece of semiconductor material, with three terminals for
connection to an external circuit.
The essential usefulness of a transistor comes from its ability to use a small signal to control a much larger signal,
enabling it to act as an amplifier. Alternatively, it can be used to turn current on or off in a circuit as an electrically
controlled switch, where the amount of current is determined by other circuit elements.
First working
transistor, built in
1947
Intel Core i7 chip (2008)
containing more than
700 million transistors
Silicon is the main material from which semiconductors are made. Pure silicon is not a conductor. However, it can
be made conductive by adding other elements to its structure, which then becomes known as N-type or P-type
silicon. This process is called doping.
N-type silicon is silicon that has been chemically combined (doped) with phosphorus gas to make it conductive. In
contrast, p-type silicon is silicon doped with boron gas which turns it into a conductive material.
A bipolar transistor is like a sandwich made of a combination of N- and P-type silicon. The filling of the sandwich is
a very thin region called base (B), and the two slices of bread are called collector (C) and emitter (E). The base,
collector and emitter are the three connecting terminals of the transistor.
There are two basic types of bipolar transistor constructions, PNP and NPN, which basically describe the physical
arrangement of the P-type and N-type semiconductor materials from which they are made.
Bipolar transistors have the ability to operate within three different regions:



Active Region - the transistor operates as an amplifier and Ic = β.Ib
Saturation Region - the transistor is “Fully-ON”, operating as a switch and Ic = I (saturation)
Cut-off Region - the transistor is “Fully-OFF”, operating as a switch and Ic = 0
The principle of operation of the two transistor types PNP and NPN, is exactly the same, the only difference being
and the polarity of the power supply for each type.
The construction and circuit symbols for both the PNP and NPN bipolar transistor are given above. The arrows in
the circuit symbols always show the direction of current flow between the base terminal and its emitter terminal.
The direction of the arrow always points from the positive P-type region to the negative N-type region for both
transistor types, exactly the same as for the standard diode symbol.
As the bipolar transistor is a three-terminal device, there are basically three possible ways to connect it within an
electronic circuit, with one terminal being common to both the input and output:



Common Base Configuration - has Voltage Gain but no Current Gain.
Common Emitter Configuration - has both Current and Voltage Gain.
Common Collector Configuration - has Current Gain but no Voltage Gain.
Source: http://www.electronics-tutorials.ws/transistor/tran_1.html (May 2014)
Task 2 Decide whether these statements are true (T) or false (F) according to the text. Correct the statements
that are false to make them true.
1.
2.
3.
4.
5.
6.
7.
8.
9.
A transistor can be used as an amplifier because it can use a small signal to control a much larger signal. ____
All semiconductors are made from silicon. ____
Doping is the process of removing impurities from silicon. ____
N-type silicon is silicon to which phosphorous has been added. ____
The middle section of a transistor is called its collector. ____
The base, emitter and anode are the three connecting terminals of a transistor. ____
A transistor is best used as an amplifier when it is operating in the saturation region. ____
A transistor is said to be “Fully-ON” when it is operating in the active region. ____
The direction of the arrow in a transistor symbol always points from the positive P-type region to the negative
N-type region. ____
10. When you connect a bipolar transistor in the common emitter configuration, there is both current and
voltage gain. ____
Task 3 Translate the following terms into English. All the answers are from the text.
TERMS IN SLOVENE
1. tranzistor
2. polprevodnik
3. priključne sponke
4. ojačevalnik
5. stikalo
6. prevodnik
7. dopiranje
8. baza
9. kolektor
10. emitor
11. linearno aktivno področje
12. področje nasičenja
13. področje zapore
14. dioda
15. napetostno ojačenje
16. tokovno ojačenje
17. orientacija s skupno bazo
18. orientacija s skupnim emitorjem
19. orientacija s skupnim kolektorjem
ENGLISH TRANSLATION (FROM TEXT)