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DIGITAL SYSTEMS
ECE-273, Digital Systems
Dr. Herb Kaufman
Electrical and Computer Engineering
UofM-Dearborn
www.engin.umd.umich.edu/~hkaufm/273files
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Required Textbook
 Fundamentals of Logic Design 5th Edition
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Charles H. Roth, Jr.
ISBN 0-534-37804-8
(C) 2004
-- See Syllabus for further information about the course
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Analog versus Digital
Analog Voltage meter
Digital Voltage meter
103.5
About 100
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Analog
Continuous Spectrum
Digital
Distinct Steps
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Analog vs. Digital
 Analog
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Continuous
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Time
 Every time has a value associated with it, not just some times
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Magnitude
 A variable can take on any value within a range
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e.g.
 temperature, voltage, current, weight, length, brightness, color
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Analog vs. Digital
 Digital
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Discontinuous
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Time (discretized)
 The variable is only defined at certain times
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Magnitude (quantized)
 The variable can only take on values from a finite set
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e.g.
 Switch position, digital logic, Dow-Jones Industrial, lottery,
batting-average
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Analog to Digital
 A Continuous Signal is Sampled at Some
Time and Converted to a Quantized
Representation of its Magnitude at that Time
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Samples are usually taken at regular intervals
and controlled by a clock signal
The magnitude of the signal is stored as a
sequence of binary valued (0,1) bits according to
some encoding scheme
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Quantization
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Digital to Analog
 A Binary Valued, B = { 0, 1 }, Code Word
can be Converted to its Analog Value
 Output of D/A Usually Passed Through
Analog Low Pass Filter to Approximate a
Continuous Signal
 Many Applications Construct a Signal
Digitally and then D/A
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e.g., RF Transmitters, Signal Generators
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Digital is Ubiquitous
 Electronic Circuits based on Digital
Principles are Widely Used
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Automotive Engine/Speed Controllers
Microwave Oven Controllers
Heating Duct Controls
Digital Watches
Cellular Phones
Video Games
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Why Digital?
 Increased Noise Immunity
 Reliable
 Inexpensive
 Programmable
 Easy to Compute Nonlinear Functions
 Reproducible
 Small
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Digital Data – Another Advantage
 Digital data can have additional data added to it to
allow for detection and correction of errors
-- (EDAC – Error Detection and Correction)
 Digital data can be transmitted over a medium that
introduces errors that are corrected at receiving
end
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Satellite transmission of Direct TV - each ‘screen’
image is digitally encoded; errors corrected when it
reaches your digital receiver, shows up as a ‘Perfect’
Picture.
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Digital Design Process
 Computer Aided Design Tools
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Design entry
Synthesis
Verification and simulation
Physical design
Fabrication
Testing
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