Patents by Inventor Torbjorn I. Randahl

Torbjorn I. Randahl has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5553132
    Abstract: To generate a ringing signal by means of a subscriber line interface circuit having two final stages, each for supplying an individual subscriber line wire, one of the subscriber line wires is connected to one of the input terminals of an operational amplifier, the other input terminal of which being connected to the interconnecting point between two series connected resistors having the same resistance. The output terminal of the operational amplifier is connected, via a first resistor, to a current input terminal of the subscriber line interface circuit for generating a first current. A signal generator, via a second resistor, is also connected to said current input terminal for generating a second current. The final stages of the subscriber line interface circuit are supplied with current from current input terminal to drive the final stages to generate the ringing signal.
    Type: Grant
    Filed: January 20, 1995
    Date of Patent: September 3, 1996
    Assignee: Telefonaktiebolaget LM Ericsson
    Inventor: Torbjorn I. Randahl