1. Intro to Engineering Electronics
Lecture 3: Transistors
Introduction to some broadly useful concepts in Electrical and Computer Engineering
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

2. Intro to Engineering Electronics
Review
Voltage, Current
Ohm’s Law
Kirchoff’s Laws for Voltage and Current
Equivalent Resistance
Series Combinations
Parallel Combinations
Diode I-V Characteristics
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

3. Intro to Engineering Electronics
Ohm’s Law
Kirchoff’s Voltage Law
Kirchoff’s Current Law
Series Equivalent
Parallel Equivalent
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

4. Intro to Engineering Electronics
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

5. Intro to Engineering Electronics
Voltage Across REQ1
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

6. Resistor V-I Characteristic
Resistors obey Ohm’s Law
Voltage is proportional to Current
Voltage vs. Current is a straight line
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

7. Diode V-I Characteristic
For ideal diode, current flows only one way
Real diode is close to ideal
Ideal Diode
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

8. Transistor: A Combination of 2 Diodes
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

9. Intro to Engineering Electronics
Diodes
We have noted previously that diodes act like a flapper valve
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

10. Intro to Engineering Electronics
Transistor
2 P-N Junctions
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

11. Intro to Engineering Electronics
MOSFET
Applying a gate voltage that exceeds the threshold voltage opens up the channel between the source and the drain
This is from an excellent collection of java applets at SUNY Buffalo
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

12. Intro to Engineering Electronics
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

13. 2 Minute Quiz Connect the Items on the Left With Those on the Right I
Name________________
2 Minute Quiz Connect the Items on the Left With Those on the Right I
Section________
Kirchoff Voltage Law
R/2
Voltage V divided by Current I
The sum of all currents into a node is zero
KVL
Resistance R
The parallel combination of two equal resistors R
KCL
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

14. Intro to Engineering Electronics
Transistor Models
2 Diodes
Current enters one terminal, is controlled by a second terminal and exits the third terminal. Thus, it acts like a valve.
Valves can be fully open, fully closed, or part way open
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

15. Transistor Models Continued
If the control signal changes with time, the total current passing through the transistor changes in the same way, but at a much higher amplitude
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

16. Transistor Models Continued
Simple circuit model of transistor
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

17. Transistor Models Continued
Transistor as a switch
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

18. Transistor Models Continued
Transistor as logic gate (Inverter)
Input
Output 1
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

19. Intro to Engineering Electronics
Models
There are usually many, many models for engineering devices and systems
Models vary in sophistication and complexity
You can use a model that you understand fully or that you are sure you are applying correctly
Use the simplest model that contains the information required
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

20. Intro to Engineering Electronics
Models Continued
Circuit components usually require more complex models at
High frequency
High power
High or low temperature
High levels of radiation
Small size
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

21. Intro to Engineering Electronics
Models: Logic Gates
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

22. Intro to Engineering Electronics
Logic Gate: XOR (a)
Question: What common household switch configuration corresponds to an XOR?
Input
Output A B X 1
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

23. Intro to Engineering Electronics
Models: Black Boxes
Logic gate models are examples of Black Boxes
The inner workings of the model are not of interest
There is a well-defined relationship between the input and the output
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

24. Intro to Engineering Electronics
Black Box Examples
Amplifier
Logic Ckt
XOR Gate
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

25. Intro to Engineering Electronics
Clapper Circuit
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

26. Models: Black Boxes Cont.
Signals and Systems
20 September September 2018
Intro to Engineering Electronics
K. A. Connor

27. Where Will You See This Information Next?
V, I, R, Kirchoff’s Laws, Combining Resistors: ECSE-2010 Electric Circuits
Diode and Transistor Theory and Electronic Design: ECSE-2050 Analog Electronics, ECSE-2060 Digital Electronics and ECSE-2210 Microelectronics Technology
Logic Design: ECSE-2610 Computer Components and Operations
Signals and Black Box Models: ECSE-2410 Signals and Systems
20 September September 2018
Intro to Engineering Electronics
K. A. Connor