EMI filter and frequency filters having capacitor with inductance cancellation loop

Publication Date
2007-02-20Filing Date
2004-12-17Inventor
Lee, Fred C.
Odendaal, Willem G.
Wang, Shuo
Metadata
Show full item recordAbstract
An electromagnetic interference (EMI) filter or frequency filters (e.g. bandpass or band reject filters) in which a capacitor has an inductance cancellation loop. Inductive coupling between capacitors can allow undesired high frequencies to propagate across a filter. This is particularly a concern when the capacitors are oriented in parallel. In the present invention, the inductance cancellation loop is disposed adjacent to one capacitor so that mutual inductance between the capacitors is reduced. The attenuation of the filter at high frequencies is thereby increased. The loop can increase voltage attenuation of an EMI filter by about 20 dB. In another aspect, inductors in the filter are oriented horizontally relative to a circuitboard. Horizontal orientation reduces leakage inductance coupling between the inductors and circuitboard traces, and between the inductor and capacitors, thereby preventing unwanted propagation of high frequencies. Both measures in combination can provide a voltage attenuation increase of 30 dB.
Assignee
Virginia Tech Intellectual Properties, Inc.
Patent Number
7180389
Application Number
11013930
Primary/U.S. Class
333/181
Other/U.S. Class
333/185
361/306.2
CPC Class
H03H7/427
H03H7/175
H03H7/1758
H03H7/1766
H03H7/1775
H03H2001/005
H04B3/28
Patent Type
utility
Collections
- Virginia Tech Patents [621]