Intro to Engineering Electronics Lecture 3: Transistors Introduction to some broadly useful concepts in Electrical and Computer Engineering 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Ohm’s Law Kirchoff’s Voltage Law Kirchoff’s Current Law Series Equivalent Parallel Equivalent 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Voltage Across REQ1 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Resistor V-I Characteristic Resistors obey Ohm’s Law Voltage is proportional to Current Voltage vs. Current is a straight line 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Diode V-I Characteristic For ideal diode, current flows only one way Real diode is close to ideal Ideal Diode 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Transistor: A Combination of 2 Diodes 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Diodes We have noted previously that diodes act like a flapper valve 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Transistor 2 P-N Junctions 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 http://jas.eng.buffalo.edu/ 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Transistor Models Continued Simple circuit model of transistor 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Transistor Models Continued Transistor as a switch 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Transistor Models Continued Transistor as logic gate (Inverter) Input Output 1 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Models: Logic Gates 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Black Box Examples Amplifier Logic Ckt XOR Gate 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Intro to Engineering Electronics Clapper Circuit 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

Models: Black Boxes Cont. Signals and Systems 20 September 201820 September 2018 Intro to Engineering Electronics K. A. Connor

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 201820 September 2018 Intro to Engineering Electronics K. A. Connor