Wave transmission lines and networks – Coupling networks – Frequency domain filters utilizing only lumped parameters
Reexamination Certificate
2007-02-20
2007-02-20
Ham, Seungsook (Department: 2817)
Wave transmission lines and networks
Coupling networks
Frequency domain filters utilizing only lumped parameters
C333S185000, C361S306200
Reexamination Certificate
active
11013930
ABSTRACT:
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.
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Neugebauer, T.C., et al., “Filters and Components with Inductance Cancellation”, IEEE Transactions on Industry Applns., vol. 40, No. 2, pp. 483-491 (Mar. 2004).
Neugebauer, T.C., et al., “Filters with Inductance Cancellation Using Printed Circuit Board Transformers”, IEEE Transactions on Power Electronics, vol. 19, No. 3, pp. 591-602 (May 2004).
Lee Fred C.
Odendaal Williem Gerhardus
Wang Shuo
Ham Seungsook
Virginia Tech Intellectual Properties Inc.
Whitham Curtis Christofferson & Cook, P.C.
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