Distortion-free chopper-based signal mixer
CA 2196938 A1 · Owner: Whitecar, John Elliott · Inventors: Harris, Richard Bruce; Hirschenberger, Frank Michael; Whitecar, John Elliott
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An AM-modulated carrier signal is converted to a lower carrier frequency through mixing with a square wave local oscillator signal. A field-effect transistor chops the modulated signal according to the square wave signal so that a chopped or sampled version of the modulated signal is created without passing the signal through a semiconductor junction. A filter then selects the desired mixing product. Thus, a distortion free mixing of the signal is obtained using low cost components including a JFET switch and a square wave output from a microcontroller.
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 6, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended February 6, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 6, 2019.
- 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.