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Signal Integrity Research of High Speed Circuit of Embedded System

Signal Integrity Research of High Speed Circuit of Embedded System. Kaihua Xu 1 , Jun Zhou 1 , Yuhua Liu 2 , and Shuyun Dong 1 1 College of Physical Science and Technology, HuaZhong Normal University, Wuhan 430079, China

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Signal Integrity Research of High Speed Circuit of Embedded System

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  1. Signal Integrity Research of High Speed Circuit of Embedded System Kaihua Xu1, Jun Zhou1 , Yuhua Liu2, and Shuyun Dong1 1College of Physical Science and Technology, HuaZhong Normal University, Wuhan 430079, China 2Department of Computer Science, HuaZhong Normal University, Wuhan 430079, China E-mail:xukh@ phy.ccnu.edu.cn

  2. Overview • What is Signal Integrity (SI)? • What is crosstalk? • What is reflection ? • The mechanisms of crosstalk and Reflection • Signal integrity simulation • SI Roles

  3. What is Signal Integrity (SI)? • That ensures all signals transmitted are received correctly • That ensures signals don’t interfere with one another in a way to degrade reception. • That ensures signal don’t damage any device • That ensures signal don’t pollute the electromagnetic spectrum

  4. Mutual Capacitance, Cm Zo Zo far near Zs Zo What is crosstalk? • Crosstalk is the coupling of energy from one line to another via: • Mutual capacitance (electric field) • Mutual inductance (magnetic field) Mutual Inductance, Lm Zo Zo far Cm Lm near Zs Zo

  5. What is crosstalk? • The near and far end victim line currents sum to produce the near and the far end crosstalk noise Zo Zo Zo Zo far far ICm ILm Lm near near Zs Zs Zo Zo

  6. What is reflection ? • Transmission line impedance changes, reflection occurs

  7. What is reflection ? Minimize reflections • Use controlled impedance interconnects • Provide at least one termination at the ends of a transmission line. • Use a routing topology that minimizes the impact from multiple branches. • Minimize any geometry discontinuities.

  8. Mechanism of crosstalk • The circuit element that represents this transfer of energy are the following familiar equations • The mutual inductance will induce current on the victim line opposite of the driving current (Lenz’s Law) • The mutual capacitance will pass current through the mutual capacitance that flows in both directions on the victim line

  9. Time = 0 Near end crosstalk pulse at T=0 (Inear) ~Tr V Near end crosstalk Zo TD Far end crosstalk pulse at T=0 (Ifar) ~Tr Time= 1/2 TD 2TD V Zo far end crosstalk Zo Time= TD Far end of current terminated at T=TD V Zo Zo Time = 2TD Near end current terminated at T=2TD V Zo Zo Mechanism of crosstalk

  10. Mechanism of reflection • We have a equation for the reflection • equation can simplify change into a simple distribution network, such as

  11. Mechanism of reflection • Graphical Explanation

  12. Signal integrity simulation • Main Board Structure s3c2440 ,6—layer mainboard GPRS wireless communication module GPS module • Simulation Tools and Environment Mentor Graphics Corporation’s Hyperlynx IBIS model

  13. Signal integrity simulation • crosstalk network

  14. Signal integrity simulation • Photo on PCB

  15. Signal integrity simulation • after then end-to-end source signal

  16. SI Roles • Convert product parts and design features into models and parameters • Use models to simulate performance • Perform measurements to validate product • Determine how parameters limit performance • Use cost and simulated or measured performance to determine rules for design • Use margin budgets to manage designs

  17. Any queation? Thank you! Decmber 15,2009

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