Patents by Inventor Kari T. Lehtinen

Kari T. Lehtinen 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).

  • Arrangement for transmitting and receiving radio frequency signal at two frequency bands
    Patent number: 6014551
    Abstract: The present invention relates to an arrangement for transmitting a radio-frequency signal at two different frequency bands and for receiving at two different frequency bands. The arrangement can be applied for instance to a transceiver of a radio communications system operating at two different frequency bands, or to a transceiver meant to be used in connection with two different radio communications systems. One of the ideas of the invention is that one and the same filter (72), belonging to the RF front end of the antenna circuit, is used for filtering interference from at least two signals located at different frequency bands, in which case the number of filters (72, 75) can be reduced. By means of the solution suggested in the invention, also the number of controllable switches (73) provided on the signal path of the RF front end can be minimized.
    Type: Grant
    Filed: July 16, 1997
    Date of Patent: January 11, 2000
    Assignee: Nokia Mobile Phones Ltd.
    Inventors: Mikko Pesola, Kari T. Lehtinen
  • Method for generating frequencies in a direct conversion transceiver of a dual band radio communication system, a direct conversion transceiver of a dual band radio communication system and the use of this method and apparatus in a mobile station
    Patent number: 5983081
    Abstract: The invention relates to a method for generating frequencies in a direct conversion transceiver of a radio communication system operating in two different frequency bands. In this method a first frequency band comprises a first transmission frequency band and a first reception frequency band, and a second frequency band comprises a second transmission frequency band and a second reception frequency band. The frequencies are Generated by using one frequency synthesizer (12) and a reference oscillator (14), which generates an essentially constant mixing frequency (L04).
    Type: Grant
    Filed: March 25, 1997
    Date of Patent: November 9, 1999
    Assignee: Nokia Mobile Phones, Ltd.
    Inventor: Kari T. Lehtinen
  • Output power control and envelope shaping for a pulsed transmitter
    Patent number: 5675611
    Abstract: Some mobile station cellular networks use either amplitude modulation or constant envelope modulation depending on the situation. The pulsed transmitter of the mobile station is switched on and off by a first control signal (TXP) and the output power envelope shaping of the pulse to be transmitted is controlled in the feedback loop by a second control signal (TXC). According to the invention the output power is controlled by a third control signal (TXCE) which in the amplitude modulation case switches off the feedback loop for the period of the information transfer and which at other times closes the feedback loop.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: October 7, 1997
    Assignee: Nokia Mobile Phones Ltd.
    Inventors: Kari T. Lehtinen, Jouko Hakkanen