EMI drive by PI.pdf

? 2008 Ansoft, LLC All rights reserved. Ansoft, LLC Proprietary EMI Driven by PI ? 2008 Ansoft, LLC All rights reserved. Ansoft, LLC Proprietary Outline ? SI + PI = EMI – These disciplines are no longer independent of each other ? Fundamentals of EMI – Where does it come from and how is it minimized – Five Step EMC Design Flow ? Power Integrity design methodology to reduce EMI – Fundamentals of Power Integrity – Design Process to meet design specs in the Time and Frequency domain ? 2nd Presentation on EMI Driven by SI – Fundamentals of Signal Integrity ? Crosstalk is the main contributor to EMI – Case studies that show perils of crosstalk in real world designs ? 2008 Ansoft, LLC All rights reserved. Ansoft, LLC Proprietary SI/PI/EMI Design Overview Driver IC Control IC Memory Power Supplies Display Panel Signal Integrity - Impedance - Crosstalk - Reflection - Termination - Dielectric Losses Power Integrity - Switching Noise - Impedance Profile - Power/Gnd Plane Resonance - Decoupling Capacitors EMI/EMC - Common mode radiation - Differential mode radiation PCB Pwr Noise Signal Signal Integrity Time DomainFrequency Domain Power Integrity Electromagnetic Interference ? 2008 Ansoft, LLC All rights reserved. Ansoft, LLC Proprietary Three Basic Elements of EMC EMI sourceEMI source Capacitive Inductive RadiativeConductive Space FieldConduction EMSEMS Low Middle Frequency LC Resonance High FrequencyLow, Middle High Frequency Coupling process Immunity Emission ShieldsShieldsEMI FiltersEMI Filters ShieldsShields ShieldsShields ShieldsShieldsEMI FiltersEMI Filters ? 2008 Ansoft, LLC All rights reserved. Ansoft, LLC Proprietary Loop Mode Common Mode Noise A PC Board Cables A Driver Receiver A victim device Loop mode current Common mode current by AC Analysis of Q3D Extractor Differential mode current flows --- Loop Common mode current flows --- Open We can see Common mode current is more serious than Normal mode. ? 2008 Ansoft, LLC All rights reserved. Ansoft, L