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

2.1.1 Equivalent Series Inductance (ESL)

Cause: Every conductor has inductance. In leaded (through-hole) resistors, the long metal leads act as inductors. In wire-wound resistors, the coiled resistive wire creates a significant magnetic field.

Impact: As frequency increases, the impedance of the resistor rises. This makes the resistor "choke" high-frequency signals.

Mitigation: Use Surface Mount (SMD) components (like 0402 or 0603 packages) because they have almost no lead length.