STDA033 October   2026 MSPM0G3105-Q1 , MSPM0G3106-Q1 , MSPM0G3107-Q1 , MSPM0G3505-Q1 , MSPM0G3506-Q1 , MSPM0G3507-Q1 , MSPM0L1227-Q1 , MSPM0L1228-Q1 , MSPM0L2227-Q1 , MSPM0L2228-Q1 , MSPM33C321A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1.     How Does an Electromagnetic Field Start in a Circuit?
    2.     Near-Field and Far-Field Electromagnetic Fields
  5. 2Common Sources of EMI in Electronic Designs
    1. 2.1 Resistors
      1. 2.1.1 Equivalent Series Inductance (ESL)
      2. 2.1.2 Shunt Capacitance
      3. 2.1.3 Parasitic Capacitance to Ground
    2. 2.2 Capacitors
      1. 2.2.1 Equivalent Series Resistance (ESR)
      2. 2.2.2 Equivalent Series Inductance (ESL)
      3. 2.2.3 Leakage Resistance
      4. 2.2.4 Dielectric Absorption (Soakage)
    3. 2.3 Inductors
      1. 2.3.1 Direct Current Resistance (DCR)
      2. 2.3.2 Parasitic Capacitance
      3. 2.3.3 Core Losses (Magnetic Parasitics)
    4. 2.4 Summary of Discrete Component EMI Considerations
    5. 2.5 Design Deficiencies
    6. 2.6 Sources Specific to MCUs
      1. 2.6.1 Clock Circuits and Oscillators
    7. 2.7 Other Common Sources
      1. 2.7.1 High-Speed Digital Buses
      2. 2.7.2 I/O Output Transitions
      3. 2.7.3 Floating Components
      4. 2.7.4 External Environmental Sources
  6. 3Mitigation Techniques to Minimize EMI and Optimize Board Performance
    1. 3.1 Power Supply Capacitor Selection and Placement
    2. 3.2 Capacitor Placement
    3. 3.3 Layer Stack-Up Optimization
      1. 3.3.1 Good Stack-Up Traits
      2. 3.3.2 Stitching and Shielding Optimization Techniques
    4. 3.4 Trace Routing
    5. 3.5 Passive Pi Filtering
    6. 3.6 Shielding, Grounding, and Cable Boundaries
    7. 3.7 Transient and ESD Current Paths
  7. 4EMC Verification and Troubleshooting
    1. 4.1 Emissions and Immunity as Port Problems
    2. 4.2 Pre-Compliance Measurement Toolkit
    3. 4.3 A Frequency-to-Structure Debug Method
    4. 4.4 Interpreting Common Spectral Signatures
    5. 4.5 Integrated Design Review Checklist
  8. 5Conclusion

2.4 Summary of Discrete Component EMI Considerations

EMI sources can be organized into component non-idealities, PCB geometry, switching devices, digital interfaces, cables and enclosures, and external disturbances. The categories interact; a fast MCU edge excites package inductance, the resulting ringing enters a cable through connector imbalance, and the cable then becomes the dominant antenna.

Real components are frequency-dependent networks. A value printed on a schematic is only the low-frequency parameter. Package geometry, internal construction, mounting pads, vias, and nearby planes add inductance, capacitance, and loss. Component selection therefore requires impedance-versus-frequency data, not nominal value alone.

Table 2-1 Summary of Discrete Component Parasitics and EMI Considerations
ComponentDominant Non-IdealitiesEMI ConsequenceSelection Question
ResistorLead or package inductance; terminal and body capacitanceImpedance rises, then potentially falls as capacitance bypasses RIs the part non-inductive and effective at the concern frequency?
CapacitorESR, ESL, leakage, dielectric lossDecoupling becomes inductive above self resonanceWhat is impedance at the actual noise frequency and mounting geometry?
InductorDCR, inter-winding capacitance, core loss, saturationFiltering collapses above SRF or under biasDoes inductance remain adequate at DC bias and frequency?