Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
1999-03-23
2001-02-27
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S232000
Reexamination Certificate
active
06194987
ABSTRACT:
BACKGROUND
The present invention relates to an inductance means. The invention also relates to an integrated circuit chip including such an inductance means.
A circuit component is frequently described as having an impedance Z with a resistive part and a reactive part. In other words a component has a resistance R and a reactance X. The reactance X may include an inductive component, rendering the impedance of the component inductive and resistive.
The article “SiIc-Compatible Inductors and LC Passive Filters” (IEEE Journal of Solid-State Circuits, Vol. 25, No. 4, 1990) by N. M. Nguyen and R. G. Meyer, discloses a square spiral inductor which is fabricated of aluminium on a silicon substrate. The disclosed inductor having an inductance of 9.7 nH also had a series resistance of 15.4 Ohm and a maximum Q-value below 4 at 0.9 GHz. Hence, the performance of the disclosed inductor is limited by the metal resistance.
The article “Microwave Inductors and Capacitors in Standard Multilevel Interconnect Silicon Technology” (IEEE Transactions on Microwave Theory and Technique, Vol. 44, No 1 January 1996) discloses a spiral inductor on a silicon substrate. The disclosed inductor has four turns, and thicker metal wires which are realized in standard 0.8 micrometer BiCMOS silicon technology by connecting multiple metal layers with dense via arrays. The disclosed spiral inductor has three metal levels mutually connected with a via array, and an underpass at a lowest of four metal levels provided in the silicon substrate. The article reports an estimated Q-value of 9.3 at 4 GHz for such an inductor.
SUMMARY
The invention relates to the problem of providing an inductor having an advantageously high Q-value. More particularly the invention relates to the problem of providing an inductance device having a low resistive loss while providing a high inductance value.
Furthermore the invention relates to the problem of providing an integrated circuit inductor with advantageous performance characteristics at high frequencies. Integrated circuit inductors according to the prior art suffer from particularly low Q-values.
A further object of the invention is to achieve an integrated circuit inductor operating at frequencies above 300 MHz with an improved Q-value.
These problems are addressed, according to an embodiment of the invention, by providing an inductance means comprising a first and a second terminal and two conductors. Each conductor forms a loop between the terminals such that a current provided to the first terminal is divided between the conductors. Each current generates a magnetic field. The conductors are disposed such that the combined magnetic field generated by the conductor currents in a space between the conductors is greater than the magnetic field generated by each of the conductors in that space.
This design has the advantage of reducing the resistance value for the inductance device since—from an electric point of view—the two conductors are coupled in parallel.
Advantageously, this design also has the surprising effect of providing a high inductance value. This is particularly surprising since it is common knowledge in the art of electrotechnology that parallel coupling of inductors leads to lower net inductance, under the same principle governing parallel coupling of resistance.
The inductance device also obtains an advantageously increased quality factor.
A further advantage afforded by the inductance device according to embodiments of the invention is the reduction or elimination of electromagnetic interference on other circuits or components disposed next to the inductance device.
REFERENCES:
patent: 2843829 (1958-07-01), Slate
patent: 4638270 (1987-01-01), Machemer
patent: 5034717 (1991-07-01), Shinkai
patent: 5852866 (1998-12-01), Kuettner et al.
patent: 5886394 (1999-03-01), Leeuwenburgh
patent: 5892425 (1999-04-01), Kuhn et al.
Nguyen et al., “Silc-Compatible Inductors and LC Passive Filters”,IEEE Journal of Solid-State Circuits, vol. 25, No. 4, 1990 No Date.
“Microwave Inductors and Capacitors in Standard Multilevel Interconnect Silicon Technology”IEEE Transactions on Microwave Theory and Technique, vol. 44, No. 1, Jan. 1996.
Lewin Per Thomas
Zhou Shu-Ang
Burns Doane Swecker & Mathis L.L.P.
Donovan Lincoln
Nguyen Tuyen
Telefonaktiebolaget LM Ericsson
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