lec2_fund_basics_digital_signaling

lec2_fund_basics_digital_signaling - Fundamentals and...

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Fundamentals and basics of Digital Signaling Fundamentals and basics of Digital Signaling Ref: Fundamentals of Microsystems Packaging, Chapter 4 Digital Signal Integrity, ISBN 0-13-028904-3 Class Notes
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Fundamentals and basics of Digital Signaling How do Computers Process How do Computers Process Information? Information? Performance = ( μ P Speed) (MIPS/MHz) ( μ P Utilization) ) 1 ( ) ( MP CPI F MIPS Perf + = F: μ P’s frequency in MHz; CPI: Average cycles per instruction for an infinite L1 cache; MP: Memory penalty caused by cache misses
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Fundamentals and basics of Digital Signaling Memory hierarchies for microprocessor-based Systems No L2 Cache L2 Cache on System bus Inline L2 Cache Backdoor Cache
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Fundamentals and basics of Digital Signaling Digital Systems with Digital Systems with Components Components
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Fundamentals and basics of Digital Signaling System Characteristics System Characteristics Type Typical μ P Utilization μ P Speed (MHz) Bus Speed (MHz) Bus Width (bits) NT Servers 20-40 600 100 64 Unix RISC Servers 40-60 600 200 128 Mainframe Servers >90 630 315 512
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Fundamentals and basics of Digital Signaling High-Speed Design Issues CROSSTALK INTERCONNECT DELAY GROUND BOUNCE ATTENUATION REFLECTION RADIATION EMI SUSCEPTIBILITY THERMAL NOISE Ref: R. Achar, EDAPS Tutorial, Dec 2005
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Fundamentals and basics of Digital Signaling Chip to Chip Signaling Chip to Chip Signaling data-out data-in Zo, To Pkg B Board Trace Pkg A Chip A Chip B τ Driver Receiver Interconnections
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Fundamentals and basics of Digital Signaling τ = 1ns τ = 0.1ns Time-Freq Relations τ
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Fundamentals and basics of Digital Signaling Time – Frequency Relation V 0 T w τ T t 0 )) 2 cos( / ) / sin( / ) / sin( 2 1 ( ) ( 1 0 t T n T n T n T T n T T n T T V t v n w w w π πτ = + = Fourier Series Representation
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Fundamentals and basics of Digital Signaling Time – Frequency Relation Spectrum 2.78/T w 2.78/ τ ϖ n -20dB/decade -40dB/decade ϖ n,max = 5.56/ τ or f n,max = 0.885/ τ Required Bandwidth or frequency content of the signal is f max ~ 1/ τ
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Fundamentals and basics of Digital Signaling Time – Frequency Relation τ = 0.1ns f max = 10 GHz f max 1 τ = Sharper pulses contain higher frequency harmonics d f max is the highest frequency component that needs to be supported on the interconnect τ
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Fundamentals and basics of Digital Signaling min λ d1 Wavelength corresponding to f max Interconnect Length max min f v Frequency Velocity Wavelength = ⇒⇒⇒ = Concept of Wavelength d2 These two interconnects behave differently
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Fundamentals and basics of Digital Signaling Wavelength vs Interconnect Length When?? for digital systems…. d When Interconnect length becomes comparable to the Wavelength Transmission line (TLine) effects become prominent λ v f __ = Frequency = 1GHz v f __ λ 1 .5 × 1 0 1 0 1 × 1 0 9 = = 15cm d ~ 1.5cm Lines longer than 1.5 cm behave as TLines
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Fundamentals and basics of Digital Signaling Signaling for Synchronous Digital Systems
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This note was uploaded on 04/28/2008 for the course ECE 4460 taught by Professor Swaminathan during the Spring '08 term at Georgia Tech.

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lec2_fund_basics_digital_signaling - Fundamentals and...

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