EE 261 – Introduction to Logic Circuits
Module #1 – Analog vs. Digital
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Topics
A. Course Overview
B. Analog vs. Digital
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Textbook Reading Assignments
 1.1 – 1.12
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Practice Problems
 1.5
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Graded Components of this Module
 1 homework, 1 discussion, 1 quiz
(all online)
EE 261 – Introduction to Logic Circuits
Module #1
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EE 261 – Introduction to Logic Circuits
Module #1 – Analog vs. Digital
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What you should be able to do after this module
 Describe the difference between an analog and a digital signal
 Give examples of analog and digital applications
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Course Overview
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Instructor:
Brock J. LaMeres
Office :
533 Cobleigh Hall
Phone :
(406)-994-5987
Email :
lameres@ece.montana.edu
Web :
www.coe.montana.edu/ee/lameres/
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Textbook:
“Digital Design: Principles and Practices", (Required)
4th Addition
John F. Wakerly,
Prentice Hall, 2006
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Website:
ecat.montana.edu
- this is the Desire 2 Learn (D2L) course management system.
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Requisites:
Pre/Co-requisite MATH 181
EE 261 – Introduction to Logic Circuits
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Course Overview
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Course Plan
- there are 8 modules that will be covered in this course.
- each of these modules will consists of:
1) Textbook reading assignments
2) Lecture note reading assignments
3) Video tutorials (select topics)
4) Practice Problems (ungraded, solutions provided)
5) Homework Problems (weekly, 1-3 per module, graded)
6) Discussions (weekly, 1-3 per module, graded)
7) Quiz (1 per module, graded)
- There will be a comprehensive final exam at the end
of the semester.
- The homework, discussions, and quizzes have
due dates that follow a typical 16 week semester
course schedule.
- You can work ahead, but you can’t fall behind!
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Analog vs. Digital
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What is an Analog Signal?
- The signal is the real information. We care about the signal's value at every moment of time.
- An analog signal is a time varying signal that can take on any value across a continuous range.
or
- Any variable that is continuous in both time and amplitude
i.e., there is information on the signal at all moments in time (no gaps)
i.e., time moves forward
i.e, it cannot change amplitudes instantaneously (we construct special math for these cases)
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Examples
- sound, light, smell, a sine wave, electricity from the wall
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We live in an analog world. Our senses are analog.
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Analog vs. Digital
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What is a Digital Signal?
- The signal is a representation of the information.
or
- Representations of discrete-time signals, typically derived from analog signals.
- We are not sending the actual data, just a coded description of it. The receiver will decode it and
know what you meant.
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Examples
- Morris Code
- A smile or frown
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Since we live in an analog world, digital information must be converted
back to analog in order for humans to sense it.
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Analog vs. Digital
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Disadvantages of Analog Signals
- The universe is filled with electrical noise.
Thermal Noise - caused by thermal agitation of charge carriers inside an electrical conductor
Shot Noise - random fluctuations in current due to the current being composed of discrete charges (electrons)
- This noise can be present on all signals (analog or digital).
- This is a problem for analog signals because the signal represents the real information
(which now has noise on it).
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Advantages of Digital Signals
- We can have a little noise on a digital signal and still be able to determine what the
original information was.
- It is easier to fabricate a functional digital circuit than an analog circuit.
- We can shrink digital circuits much more than analog circuits.
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Analog vs. Digital
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Evolution from Analog to Digital
Photography
Music
Video
Communications
Analog
Digital
film
records, tapes
VHS
original signal
pixels
CD's, MP3'S
DVD's, LCD's
coded version
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