Lecture 18: Electrical Engineering IV

1. Lecture 18: Electrical Engineering IV EEN 112: Introduction to Electrical and Computer Engineering Professor Eric Rozier, 4/17/13

2. THERMIONIC TRIODES

3. The Thermionic Triode • Invented in 1906 by Robert von Lieben • Two important applications: Amplification, switching

4. Amplification

5. Amplification • Switching is a special form of amplification. • Amplification – See a signal? Turn it up proportionally • Switching – See a signal? Turn it up to the max, no matter what it is!

6. Switches enable some important things…

7. Thermionic Triodes • Direct heating of the cathode produces an electron charge. The stream is then attracted to the negatively charged cathode. • Applying negative charge to the control grid isolates the anode from the cathode.

8. Thermionic Triode • Amplification of the signal on the grid. • Switching by setting the charge on the grid.

9. The problem with vacuum tubes… • Draw a lot of power • Big • Hot • Fail a lot

10. SEMICONDUCTORS

11. Free electrons?

12. Holes?

13. The most important invention of the 20th century… • John Bardeen, William Shockley, and Walter Brittain are working with amplifiers. • Found a silicon one that wouldn’t work. Later made the same device out of Germanium • Bardeen discovered electrical current traveled in different ways through the crystal. • Theorized if they could control the properties in the crystal surface, they could control the flow of electrons.

14. Theory of Superconductivity

15. The Transistor • A semiconductor device used to amplify or switch electronic signals and electrical power. • Composed of semiconductor material with at least three terminals, BASE, COLLECTOR, EMITTER. The transistor is the fundamental building block of all modern electronic devices.

16. Bipolar Transistor PNP NPN

17. Bipolar Transistor Pointing iNProudly Not Pointing iN

18. PNP E C - + B +/-

19. NPN C E - + B +/-

20. Bipolar Transistor

21. Field Effect Transistor • The BJT (Bipolar Junction Transistor) relies on the contact of two types of semiconductors for its operation. • The FET (Field Effect Transistor) uses an electric field to control the shape (and conductivity) of a channel in a single type of charge carrier.

22. Field Effect Transistor

23. Field Effect Transistor • Gate • Source • Drain

24. Field Effect Transistor

25. Field Effect Transistor

26. Transitors • BJT was most commonly used from 1960 – 1970. Remains the transistor of choice for many analog circuits. • FETS used in most integrated circuits.

27. What does this show? p-channel n-channel

28. Fabrication

29. Fabrication

30. Fabrication

31. Fabrication

32. Moore’s Law

33. Moore’s Law The complexity for minimum component costs has increased at a rate of roughly a factor of two per year... Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. That means by 1975, the number of components per integrated circuit for minimum cost will be 65,000. I believe that such a large circuit can be built on a single wafer. - Gordon Moore

34. Moore’s Law