1. Intro to Engineering Electronics
Lecture 3: Transistors
Introduction to some broadly useful concepts in Electrical and Computer Engineering
Intro to Engineering Electronics
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11/29/2018

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
Intro to Engineering Electronics
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3. Intro to Engineering Electronics
Ohm’s Law
Kirchoff’s Voltage Law
Kirchoff’s Current Law
Series Equivalent
Parallel Equivalent
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4. Intro to Engineering Electronics
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5. Intro to Engineering Electronics
Voltage Across REQ1
Intro to Engineering Electronics
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6. Resistor V-I Characteristic
Resistors obey Ohm’s Law
Voltage is proportional to Current
Voltage vs. Current is a straight line
Intro to Engineering Electronics
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7. Diode V-I Characteristic
For ideal diode, current flows only one way
Real diode is close to ideal
Ideal Diode
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8. Transistor: A Combination of 2 Diodes
Intro to Engineering Electronics
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9. Intro to Engineering Electronics
Diodes
We have noted previously that diodes act like a flapper valve
Intro to Engineering Electronics
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10. Intro to Engineering Electronics
Transistor
2 P-N Junctions
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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
Intro to Engineering Electronics
STOLEN FROM K. A. Connor
11/29/2018

12. Intro to Engineering Electronics
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13. 2 Minute Quiz Connect the Items on the Left With Those on the Right
Name________________
2 Minute Quiz Connect the Items on the Left With Those on the Right
Section________
Date__________
Kirchoff Voltage Law
R/2
Voltage V divided by Current I
The sum of all currents into a node is zero
KVL
Resistance R
Intro to Engineering Electronics
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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
Intro to Engineering Electronics
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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
Intro to Engineering Electronics
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16. Transistor Models Continued
Simple circuit model of transistor
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17. Transistor Models Continued
Transistor as a switch
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18. Transistor Models Continued
Transistor as logic gate (Inverter)
Input
Output 1
Intro to Engineering Electronics
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19. 2 Minute Quiz Connect the Items on the Left With Those on the Right
Name________________
2 Minute Quiz Connect the Items on the Left With Those on the Right
Section________
Date___________
Kirchoff Voltage Law
R/2
Voltage V divided by Current I
The sum of all currents into a node is zero
The parallel combination of two equal resistors R
Intro to Engineering Electronics
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11/29/2018

20. 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
Intro to Engineering Electronics
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11/29/2018

21. 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
Intro to Engineering Electronics
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22. Intro to Engineering Electronics
Models: Logic Gates
Intro to Engineering Electronics
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23. Intro to Engineering Electronics
Logic Gate: XOR (a)
Question: What common household switch configuration corresponds to an XOR?
Input
Output A B X 1
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24. 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
Intro to Engineering Electronics
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25. Intro to Engineering Electronics
Black Box Examples
Amplifier
Logic Ckt
XOR Gate
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26. Intro to Engineering Electronics
Clapper Circuit
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27. Models: Black Boxes Cont.
Signals and Systems
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28. 2 Minute Quiz Connect the Items on the Left With Those on the Right
Name________________
2 Minute Quiz Connect the Items on the Left With Those on the Right
Section________
Date____________
Kirchoff Voltage Law
R/2
Voltage V divided by Current I
The sum of all currents into a node is zero
KCL
Intro to Engineering Electronics
STOLEN FROM K. A. Connor
11/29/2018

29. Answers Connect the Items on the Left With Those on the Right
Name________________
Answers Connect the Items on the Left With Those on the Right
Section________
Date____________
KVL
Resistance R
Kirchoff Voltage Law
R/2
Voltage V divided by Current I
The sum of all currents into a node is zero
The parallel combination of two equal resistors R
KCL
Intro to Engineering Electronics
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11/29/2018

30. 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
Intro to Engineering Electronics
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11/29/2018