DIGITAL SYSTEMS ECE-273, Digital Systems Dr. Herb Kaufman Electrical and Computer Engineering UofM-Dearborn 1

Required Textbook  Fundamentals of Logic Design 5 th Edition Charles H. Roth, Jr. ISBN (C) See Syllabus for further information about the course 2

Analog versus Digital Analog Voltage meter Digital Voltage meter About 100 3

Analog Continuous Spectrum Digital Distinct Steps 4

Analog vs. Digital  Analog Continuous Time  Every time has a value associated with it, not just some times Magnitude  A variable can take on any value within a range e.g.  temperature, voltage, current, weight, length, brightness, color 5

Analog vs. Digital  Digital Discontinuous Time (discretized)  The variable is only defined at certain times Magnitude (quantized)  The variable can only take on values from a finite set e.g.  Switch position, digital logic, Dow-Jones Industrial, lottery, batting-average 6

Analog to Digital  A Continuous Signal is Sampled at Some Time and Converted to a Quantized Representation of its Magnitude at that Time 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 7

Quantization 8

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 e.g., RF Transmitters, Signal Generators 9

Digital is Ubiquitous  Electronic Circuits based on Digital Principles are Widely Used Automotive Engine/Speed Controllers Microwave Oven Controllers Heating Duct Controls Digital Watches Cellular Phones Video Games 10

Why Digital?  Increased Noise Immunity  Reliable  Inexpensive  Programmable  Easy to Compute Nonlinear Functions  Reproducible  Small 11

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 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. 12

Digital Design Process  Computer Aided Design Tools Design entry Synthesis Verification and simulation Physical design Fabrication Testing 13