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      About Frequency

              Highest Frequency of concern IS NOT the Clock.
              IT IS Frequency of the High Harmonics necessary to create the Fast Rising Signals,
               called : Maximum Pulse Frequency.

              F(freq-GHz) = .35 / Tr(rise time-nSec*)
                        • (Tr = 10-90% (Typical))
                        • (Tf = 10-90% (Typical))
              Emission Bandwidth is from Clock to Maximum Pulse Frequency.

      
Signal Integrity Basics

             Signal Integrity is a field of study between digital design and analog circuit theory.
                       • It ' s about ringing,
                       • crosstalk,
                       • ground bounce,
                       • power supply noise.

              It's all about how to build fast digital hardware that really works.
              It's about practical, real-world solutions to high-speed design problems.
              Signal Integrity is a deterministic, predictable field of study (a "hard science").
              Signal integrity specialists make frequent use of the fact that most signal integrity
               problems are easily observed.
              A good simulation, can usually put to rest any question about the efficacy
               of a particular solution.
              Signal Integrity didn't always matter -
                       • In the golden years of digital computing (1970-1990), gates switched so slowly that,
                         digital signals actually looked like ones and zeros.
              Unfortunately, those days are gone.
                       • At today's speeds even the simple, passive elements of a high-speed design -
                         the wires, PC boards, connectors, and chip packages -
                         can make up a significant part of the overall signal delay.
              These elements can cause glitches, resets, logic errors, and other problems.
              A greater percentage of PCB traces in new designs will require terminators.
              The exact delay of individual PCB traces will become more and more important.

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