CPES receives 2 U.S. patents: cancellation of inductor winding capacitance
Congratulations to CPES researchers for 2 new U.S. patents issued in June 2009!
Covering innovations in cancellation of inductor winding capacitance, these related patent applications have been sponsored by CPES IPPF (Intellectual Property Protection Fund).
Cancellation of Inductor Winding Capacitance
by Shuo Wang and Fred C. Lee
U.S. Patent: 7,554,423
Issued: June 30, 2009
Patent Abstract: An inductor device or filter such as an electromagnetic interference (EMI) filter which includes an inductor provides cancellation of parasitic capacitance of the inductor and extends high frequency performance of the inductor or filter by providing the inductor using split windings and including capacitors to couple signals corresponding to those which are passed by the equivalent parallel capacitance of the inductor to another split winding or an inductor in the ground return path. Cancellation of parasitic capacitance is provided for differential mode and common mode split windings where the split windings may be either inductively coupled or not. Forming the split windings as a bifilar winding to increase coupling coefficient further improves performance and allows cancellation (as distinct from parasitic capacitance reduction) and avoidance of resonance in circuits in which an inductor is not permitted in the ground return path.
Generalized Cancellation of Inductor Winding Capacitance (Continuation-in-part)
by Shuo Wang and Fred C. Lee
U.S. Patent: 7,548,137
Issued: June 16, 2009
Patent Abstract: An inductor device or filter such as an electromagnetic interference (EMI) filter which includes an inductor provides cancellation of parasitic capacitance of the inductor and extends high frequency performance of the inductor or filter by using an inductor network (a special case being split windings) and including capacitors to couple signals corresponding to those which are passed by the equivalent parallel capacitance of an inductor of a network of inductors such as in a multi-phase power supply of voltage converter to another inductor terminal, ground or an inductor in the ground return path. Cancellation of parasitic capacitance is provided for differential mode and common mode windings where the windings may be either inductively coupled or not. Forming the windings as a bifilar winding to increase coupling coefficient further improves performance and allows cancellation (as distinct from parasitic capacitance reduction) and avoidance of resonance in circuits in which an inductor is not permitted in the ground return path. Different inductance values and turns ratios of any or all inductors of the network, including multi-phase networks, may be accommodated.