Page 1 © 2011 Real World HF Performance of Common Mode Filter Solutions Popular EMI filters include common mode chokes (CMC), ferrite beads, and chip inductors. Data sheet characterization are typically 50Ω impedance measurements however a product’s I/O cables typically exhibit antenna impedances of 150Ω. Mechanical construction of CMCs also introduce noise mode conversion which is rarely characterized in their specifications. These issues often result in non-compliance or inadequate compliance margins. The following excerpts represent a small portion of a comprehensive study recently completed on this subject, the full study is outlined at the end of this document. March 2011 SUPERIOR HF PERFORMANCE Small, Light Low Profile Lower Cost No Current Limit No Vibration Issues The Soluti on Meeting EMC compliance for radiated emissions and susceptibility is becoming increasingly difficult. Johanson Dielectrics presents a superior low cost solution for consideration in new designs. POOR HF PERFORMANCE - Large, Heavy - Part Height - Higher Cost - Current limited - CMC Vibration Failures The Problem
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Page 1 © 2011
Real World HF Performance ofCommon Mode Filter Solutions
Popular EMI filters include common mode chokes (CMC), ferrite beads, and chip inductors. Data sheet characterization are typically 50Ω impedance measurements however a product’s I/O cables typically exhibit antenna impedances of 150Ω. Mechanical construction of CMCs also introduce noise mode conversion which is rarely characterized in their specifications. These issues often result in non-compliance or inadequate compliance margins.
The following excerpts represent a small portion of a comprehensive study recently completed on this subject, the full study is outlined at the end of this document.
March 2011
SUPERIOR HF PERFORMANCESmall, LightLow ProfileLower CostNo Current LimitNo Vibration Issues
The Solution
Meeting EMC compliance for radiated emissions and susceptibility is becoming increasingly difficult. Johanson Dielectrics presents a superior low cost solution for consideration in new designs.
POOR HF PERFORMANCE-Large, Heavy-Part Height-Higher Cost-Current limited-CMC Vibration Failures
The Problem
Page 2 © 2011
Real World HF Performance ofCommon Mode Filter Solutions
March 2011
Component Size mm DC Current 100 MHz 1 GHz Pic (not to scale)
X2Y® 0603 1.6 x 0.8 None -57dB -28dB
X2Y® 1206 3.2 x 1.6 None -57dB -28dB
X2Y® 1210 3.2 x 3.2 None -57dB -28dB
4000Ω CMC 5.0 x 3.6 200 mA -35dB -10dB
1000Ω CMC 5.0 x 4.7 1500 mA -22dB -10dB
4.7 mH CMC 9.0 x 5.9 400 mA -15dB -8dB
4.7 mH CMC 9.3 x 5.9 400 mA -14dB -12dB*
1.0 µH Inductor (2) 3.2 x 1.6 1200 mA -14dB -3dB
120Ω Ferrite Bead (2) 3.2 x 1.6 3000 mA -5dB -5dB
600Ω Ferrite Bead (2) 3.2 x 1.6 3000 mA -12dB -5dB
Relative Size Comparisons of DUTs Tested in the Study
Relative Measured CM Rejection 50Ω ZSOURCE, 150Ω ZANTENNA
Page 3 © 2011
Real World HF Performance ofCommon Mode Filter Solutions
March 2011
Measured CM Rejection 50Ω ZSOURCE, 150Ω ZANTENNA
Outline of Full Study by X2Y® Attenuators, LLC.
• Common & Differential Mode Noise Theory
• CMC Filter Solutions, Theory And Reality
• The X2Y® Filter Solution, Theory And Reality
• Comparative Measurements Of Filter Solutions
• Comparative Performance In Applications
• X2Y® Capacitor Value Selection Methods
• X2Y® Implementation Best Practices
Please contact us to arrange a complete presentation of this study.
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