Canceling the Winding Capacitance of Inductors to Greatly Improve its High Frequency Filtering Performance

Winding capacitance of inductors is detrimental to inductor's high frequency performance since high frequency current will bypass the inductance via winding capacitance. An inductor is no longer an inductor but a capacitor at high frequencies, so that it cannot effectively block high frequency current. Reducing or canceling the winding capacitance of inductors is therefore the key to improve inductor's high frequency performance, so as to extend its effective operating frequency range to 10-100 times. This is especially important to EMI filter. This invention introduces a novel idea to cancel the effects of winding capacitance, as a result, the inductor's winding capacitance is reduced by more than 95%. Both the winding capacitance of differential mode (DM) inductors and common mode (CM) inductors can be cancelled. The inductor's high frequency performance is improved by 30dB and its operating frequency range is extended by more than 10-30 times. EMI measurements show >20dB improvement.

Patent Information:

App Type	Country	Serial No.	Patent No.	File Date	Issued Date	Patent Status
US Utility	*United States	11/552,292	7,554,423	10/24/2006	6/30/2009	Expired/Unpaid Fees
US Continuation-in-Part	*United States	11/850,762	7,548,137	9/6/2007	6/16/2009	Expired/Unpaid Fees

Category(s):

Electrical

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For Information, Contact:

Li Chen

Licensing Associate

Virginia Tech Intellectual Properties, Inc.

(540) 443-9217

lchen@vtip.org

Inventors:

Shuo Wang

Fred Lee

Keywords:

Electronics