Digital Circuit Design and Simulations

1. Digital Circuit Design and Simulations Deborah Barnett, Tidehaven High School Tidehaven ISD Dr. Peng Li, Assistant Professor (faculty mentor) Department of Electrical and Computer Engineering Texas A & M University Ping-Hsiu Lee, research partner, Reagan High School, Houston ISD

2. E3 RESEARCH PROJECT • Design and analyze circuit functionality and performance. • Model basic CMOS (Complementary Metal Oxide Semiconductor) transistor behavior using simple switch models. • Verify graphical analysis (our circuit design) and model behavior using the simulation program PSPICE (an analog circuit and digital logic simulation software that runs on personal computers).

3. EXAMPLE of a circuit in action when the input is 1 pMOS transistor nMOS transistor

4. CLASSROOM PROJECT OVERVIEW The student will • investigate the development of the microchip and its uses in modern technology • construct an electrical transistor and investigate the physical design of the microchip • design simple CMOS transistors • use PSPICE to analyze their designs

5. INTEGRATED CURRICULUM In ENGLISH I • Focus on technological advances and its effects • Read articles on microchip design and development of computer technology • Use basic vocabulary by writing a synopsis of the articles.

6. INTEGRATED CURRICULUM In IPC • Introduce and use the vocabulary (transistors, resistors, capacitors, nMOS, pMOS, CMOS) and manufacturing processes of CPU’s • Lab experiment constructing circuits

7. INTEGRATED CURRICULUM In ALGEBRA 1 • Use examples for graphs and variables from scientific data, microchip historical data • Use examples for problems from formulas pertaining to electric circuits • Assignments include data pertaining to digital circuits, microchips, engineering

8. Targeted State Standards English I TEKS: (b.1.a ) Reading/Vocabulary Development. Students understand new vocabulary and use it when reading and writing. Students are expected to determine the meaning of grade-level technical academic English words in multiple content areas.

9. Targeted State Standards IPC TEKS: • (3A) analyze and evaluate scientific explanations using empirical evidence, logical reasoning, and experimental and observational testing • (5f) evaluate the transfer of electrical energy in series and parallel circuits and conductive materials.

10. Targeted State Standards Algebra 1 TEKS: • (1.A) describe independent and dependent quantities in functional relationships, • (1.D): represent relationships among quantities using concrete models, graphs, verbal descriptions, and equations, • (1.E) interpret and make decisions, predictions, and critical judgments from functional relationships,

11. ALGEBRA 1 TEKS continued • (2.C) interpret situations in terms of given graphs, • (2.D) make and interpret scatter plots, and model, predict, and make decisions and critical judgments in problem situations, • (4.A) find specific function values, • (6.B) interpret the meaning of slope from data and graphs. • (6.C) predict the effects of change in slope.

12. PROJECT OBJECTIVES The student will: • use science vocabulary such as integrated circuit, transistor, capacitor, ampere, voltage, and resistor appropriately both verbally and in written form. • determine independent and dependent variables in problem situations involving current and voltage. • use graphs to determine relationships and make predictions in problem situations involving integrated circuits.

13. PROJECT SCOPE AND SEQUENCE

14. IPC LAB for Series and Parallel Circuits Kit Components Needed: 12 047MFD capacitor 6 10MFD capacitor 18 100MFD capacitor 6 220PF 200v 6 2N2905A transistor 6 2N3053NPN transistor 12 MPSA06 transistor 12 2N3904 transistor 12 1M ohm resistor 6 1.5K 1/4w resistor 66 100 ohm 1/4w resistor 6 100K 1/4w resistor 12 10K ohm resistor 6 4.7K 1/4w resistor 12 47 ohm resistor 24 470 ohm resistor 12 47K 1/4w resistor 5 500K potentiometer 6 7 segment light detector 6 74S00N integrated circuit 6 74S90N integrated circuit 6 CD4011 integrated circuit 6 CD4511 integrated circuit 6 LM386N integrated circuit 6 LM339 integrated circuit 6 NE555N integrated circuit timer 6 SCL4049A Hex Inverter integrated circuit 6 1458 integrated circuit 12 IN4148T diode 24 Green LED 6 Red LED 6 Yellow LED 5 Photo cell (LDR) 6 Photo diode infrared detector 10 Loudspeaker 5 Pushbutton momentary switch 5 SPDT miniature slide switch 15pr Alligator clips 5 Breadboard 5 Jumper wire kits 5 Group power supply 5 Digital multimeter 1 Box large paper clips 1 Roll aluminum foil 5 Ball point pens

15. EXCERPT OF ENGLISH I READING ASSIGNMENT • The design of a transistor allows it to function as an amplifier or a switch. This is accomplished by using a small amount of electricity to control a gate on a much larger supply of electricity, much like turning a valve to control a supply of water. Transistors are composed of three parts – a base, a collector, and an emitter. The base is the gate controller device for the larger electrical supply. The collector is the larger electrical supply, and the emitter is the outlet for that supply. By sending varying levels of current from the base, the amount of current flowing through the gate from the collector may be regulated. In this way, a very small amount of current may be used to control a large amount of current, as in an amplifier. The same process is used to create the binary code for the digital processors but in this case a voltage threshold of five volts is needed to open the collector gate. In this way, the transistor is being used as a switch with a binary function: five volts – ON, less than five volts – OFF.

16. ALGEBRA 1 PROJECT LESSON PLANS

17. ALGEBRA 1 PROJECT LESSON PLANS

18. Example to Use

19. Another Example

20. PRE/POST-TEST FOCUS • Questions 1 - 10 are technical vocabulary related to the project and general questions related to engineering • Question 11 - 20 are Algebra 1 skills related to the project

21. SOME OF THE QUESTIONS Matching a. resistor b. capacitor c. transistor d. silicon ____1. A device used in electronic circuits that provides semi-conductivity is called a ? ____2. ? is a nonmetallic chemical element with low electrical conductivity. ____3. A device used in electronic circuits that holds a charge of electricity is called a ? ____4. A device used in electronic circuits used to control the flow of current is called a ?

22. SOME MORE QUESTIONS Multiple Choice Identify the choice that best completes the statement or answers the question. ____5. Persons concerned with developing economical and safe solutions to practical problems by applying mathematics and scientific knowledge are _?_. a. teachers c. policemen b. salesmen d. engineers  ____ 6. An engineer is developing a method to be used for future space travel which will change urine into drinking water without using toxic chemicals. He/she is a/an _?_ engineer. a. nuclear c. industrial b. environmental civil d. petroleum ____7. An engineer is testing the strength of the concrete used in bridge building by applying thousands of pounds of pressure to see when the concrete will collapse and crumble. He/she is a/an _?_ engineer. a. petroleum c. nuclear b. structural civil d. chemical

23. ____19. Use the formula V = IR for the following problem. V represent voltage, R represent resistance (ohms) and I represents electrical current (amperes). If an electric light bulb draws a current of 1.2 amperes at 6 volts, what is the resistance?

24. PSPICE Demonstration Step 1: Access the library using key strokes: Control G Scroll through library and click on MBREAKN3 which is the nMOS transistor. It should look like this……

25. LIBRARY

26. Click and drag the MBREAKN3 into position You will end up with this……

27. This is an nMOS transistor

28. Step 2: Access library again with Control G and select VDC VDC is voltage direct current power supply. The voltage measurement in an DC system. Click and drag twice to put 2 VDC’s on the schematic design. It should look as follows.

30. Step 3: Access library again with Control G and select a ground. Click on GND_EARTH. Click and drag 3 times to set the grounds. It should look as follows.

31. GROUNDS

32. Step 4: Click on V1 and change the name to Vd. Click on V2 and change the name to Vg. Click on the pencil on the Tool Bar and draw the wires to connect the nMOS transistor. It should look as follows.

33. Analysis Simulation Click on the current icon to set probe

34. Step 5: Set analysis for a DC Sweep for the Vd source and a nested sweep for the Vg source. Click on Simulation and the following analysis will appear.

36. ACKNOWLEDGEMENTS • Dr. Peng Li, faculty mentor, Dept of Electrical and Computer Engineering, Texas A & M University • Albert Zeng, PhD student, Dept of Electrical and Computer Engineering, Texas A & M University • TAMU E3 participating faculty • National Science Foundation (NSF) • Ping-Hsiu Lee, research partner, Reagan High School, Houston ISD THANK YOU ALL FOR A GREAT EXPERIENCE!