Patents by Inventor Philippe Ridel

Philippe Ridel 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).

  • Amplifier circuit with automatic gain control and hearing aid equipped with such a circuit
    Patent number: 4509022
    Abstract: An amplifier system comprising an input transducer, an amplifier and an output transducer connected in cascade, and an automatic gain control circuit comprising a variable resistor for taking off a voltage which varies with the signal from the input transducer and supplies said voltage to a rectifier and an RC filter. The filter output is connected to the base of a first transistor having a collector that directly drives the base of a second transistor which is connected to the input of the amplifier in such a way that it bypasses the input signal of said amplifier to a greater extent as the signal across the variable resistor increases.
    Type: Grant
    Filed: February 28, 1983
    Date of Patent: April 2, 1985
    Assignee: U.S. Philips Corporation
    Inventor: Philippe Ridel