D I S S E R T A T I O N






The Simulation of Emission from Printed Circuit Boards under a Metallic Cover






Ausgeführt zum Zwecke der Erlangung des akademischen Grades eines
Doktor der technischen Wissenschaften
eingereicht an der Technischen Universität Wien,
Fakultät für Elektrotechnik und Informationstechnik,
Institut für Mikroelektronik






von
Dipl.-Ing. Christian Poschalko


Matrikelnummer 9025237
Lorenz-Mandlgasse 39/22, 1160 Wien

Wien, im September 2009

• • Abstract
  • Kurzfassung
  • Acknowledgements
  
  
• Contents
  • List of Acronyms
  • List of Symbols
  • 1 Motivation and Objectives
  • 2 State of the art
    • 1 The three-dimensional full wave simulation approaches
    • 2 The semi-analytical approach based on EMI source multipole macro modeling
    • 3 Analytical and numerical modeling of the EMI effects to classify sources and coupling paths regarding their potential to exceed emission limits
    • 4 Analytical model for the free space radiation of a cubical enclosure intended for fast predesign investigations
    • 5 Modeling of the common mode coupling from ICs to the cavity field
  • 3 Electromagnetic emissions mechanisms from PCBs
    • 1 Conducted emission - Radiated emission
    • 2 Direct radiation from PCB sources
    • 3 Emissions through galvanic coupling, electric and magnetic near field coupling to cables, long nets, and mechanical structures, interpreted as antennas
  • 4 Cavity model of the electromagnetic field between PCB and metallic cover
    • 1 Derivation of the two-dimensional Helmholtz equation model
    • 2 Analytical solution methods for the two-dimensional Helmholtz equation
    • 3 Inductance, capacitance, resistance (LCR) grid solution method for the two-dimensional Helmholtz equation
    • 4 FEM solution for the two-dimensional Helmholtz equation
  • 5 Introduction of sources and PCB layout structures to the cavity model
    • 1 Calculation of $K_{couple}$ with mode decomposition
    • 2 Expression of $K_{couple}$ by a distance ratio factor
    • 3 Validation of the trace introduction by HFSS^® simulations
    • 4 Independence of the common mode coupling from the horizontal trace routing
    • 5 Link of the common mode coupling to the near field above the PCB
    • 6 Modeling the coupling from integrated circuits
    • 7 Link to the current driven common mode mechanism and the common mode inductance of a trace inside a cavity.
    • 8 Design consequences
    • 9 Necessity to consider the influence of the external environment at the cavity field simulation
  • 6 Domain decomposition with PMC boundaries and port interfaces
  • 7 Analytical model for the radiated emissions from the slot of a rectangular enclosure:
    • 1 Analytical cavity model for a rectangular enclosure with three closed edges and one open slot
    • 2 Analytical consideration of the radiation loss and a model for the free space radiation from the enclosure slot
    • 3 Comparison of the analytical model results to HFSS^® simulations and measurement results
    • 4 Radiation diagrams for the rectangular enclosure with a slot on one edge
  • 8 Design rules for PCBs inside a metallic enclosure with apertures
    • 1 Rule 1: Trace placement symmetric to the enclosure symmetry reduces the coupling up to the second enclosure resonance
    • 2 Rule 2: Trace placement parallel and close to metallic enclosure walls reduces EMI, trace placement orthogonal and close to enclosure walls increases EMI
    • 3 Rule 3: Trace placement in the middle of the enclosure slot reduces the EMI at the first resonance
    • 4 Rule 4: Reduction of the trace height $d$ above the ground plane reduces EMI
    • 5 Rule 5: Single source placement closer to an enclosure wall reduces EMI
    • 6 Rule 6: Shielding reduces the common mode coupling
    • 7 Rule 7: A ground plane under an IC reduces EMI
    • 8 Summary of the design guidelines
  
  
• Part : Appendices
  • A. Validation of the analytic common-mode coupling factor $d/h$
    • 1 Variation of the trace position
    • 2 Variation of the enclosure height and the trace height above the ground plane, comparisons of the transfer impedance for parallel planes with four open edges and comparison of the transfer impedance for the two different trace routings in Figure 5.7
  
  
• Bibliography
  • Own Publications
  • Part : Curriculum Vitae
  
  
• About this document ...

C. Poschalko: The Simulation of Emission from Printed Circuit Boards under a Metallic Cover