Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2000-03-09
2001-11-06
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S202000, C333S219000
Reexamination Certificate
active
06313719
ABSTRACT:
TECHNICAL FIELD
This invention relates to electrical filters.
BACKGROUND OF THE INVENTION
Transmitter and/or receiver (henceforth referred to generically as “transceiver”) technology has evolved over the decades from the use of wires, electro-mechanical components, and machined waveguide structures to the use of coax and thick film/thin film microstrip/stripline-based circuitry. But even with this evolution, the recent proliferation of, and resulting stiff competition among, wireless communications products have led to price/performance demands on transceivers that conventional technologies find difficult to meet. And some of the more expensive components of a transceiver are the “front end” filters.
Planar filters have been of interest to transceiver designers in recent years because of their relatively small size, low cost, and ease of manufacture. A planar filter is generally implemented using flat transmission-line structures, such as microstrip and stripline transmission lines separated from a ground plane by a dielectric layer. A typical implementation defines the planar filter as conductive traces on one side of a printed circuit (PC) board, defines the ground plane as a conductive layer on the other side of the PC board, and uses the laminate of the PC board for the dielectric. An illustrative example of such a planar filter is disclosed in U.S. Pat. No. 5,990,765.
Although the use of planar filters is advantageous, the planar-filter designs known to the inventors do not take sufficient advantage of the filter configuration and layout to maximize filter performance.
SUMMARY OF THE INVENTION
This invention is directed to solving these and other problems and disadvantages of the prior art. According to the invention, a filter of electrical signals comprises a signal input, a signal output, and one or more resonator elements coupled serially end-to-end between the input and the output across gaps that separate the one or more elements from the input, the output, and each other. Significantly, the one or more elements form a serpentine shape such that at least two portions of the serpentine shape are positioned side-by-side parallel to each other. The side-by-side portions effect additional coupling between the resonator elements. Preferably, the filter is a band pass filter, and the additional coupling forms a notch in the passband of the filter.
The invention provides a low-cost, high-performance filter, e.g., for radio frequency and microwave communications systems. It can be integrated with advanced packaging technology for no tuning and a better performance (steeper skirts on the filter passband) than conventional filter designs deliver, to achieve an overall improvement in transceiver performance.
These and other features and advantages of the invention will become more apparent from the following description of an illustrative embodiment of the invention considered together with the drawing.
REFERENCES:
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Oates, D.E. et al: “Superconducting Thin-Film YBA2CU307-X Resonators And Filters”, May 29, 1991, Proceedings Of The Annual Symposium On Frequency Control, US, New York, IEEE, vol. SYMP. 45, pp. 460-466.
Takemoto, J.H. et al.: “High-TC Superconducting Microstrip Resonators And Filters On LAAI03”, May 29, 1991, Proceedings Of The Annual Symposium On Frequency Control, US, New York, IEEE, vol. SYMP. 45, pp. 477-481.
Barnett Ron
Low Yee Leng
Ma Zhengxiang
Tai King L
Wu Hui
Avaya Technology Corp.
Jones Stephen E.
Pascal Robert
Volejnicek David
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