Analog phase shifter
CA 2036099 C · Owner: American Telephone And Telegraph Company · Inventors: Daughters, Timothy E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An analog voltage-controlled phase shifter is disclosed which is smaller in size and provides a larger phase shift for a smaller change of capacitance ofpresently available voltage controlled phase shifters. These unexpected advantages are obtained by using lumped elements to simulate the normally used ?/4 transmission lines of the hybrid portion of the phase shifter and by eliminating or reducing the value of the capacitors normally present at the varactor nodes of the hybrid. The capacitance fully or partially removed from the varactor nodes of the hybrid can be selectively fully or partially added to the varactors.
Read the whole patent
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 February 11, 1991 and granted October 18, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 11, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 11, 2013.
- 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.