Cascaded surface wave device filters
CA 2178438 C · Owner: Northern Telecom Limited · Inventors: Xu, Yufeng; Chen, Zhuo-Hui; Dai, Ji-Dong
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A cascaded surface wave device filter comprises two 2-pole surface wave device filters connected in cascade. The 2-pole filters each provide a balun function between balanced and unbalanced signal connections and have either their unbalanced or their balanced signal connections interconnected in the cascade to reduce electro-magnetic feedthrough and improve spurious mode suppression. The 2-pole filters are conveniently longitudinally coupled double mode surface wave resonators which are described or transversely coupled double mode surface wave resonators. Higher order filters can be provided by connecting further 2-pole filters in the cascade. The cascaded filter is particularly useful for …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed June 6, 1996 and granted November 20, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended June 6, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by June 6, 2018.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.