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Transmitter

  • US 6,625,470 B1
  • Filed: 03/02/2000
  • Issued: 09/23/2003
  • Est. Priority Date: 03/02/2000
  • Status: Expired due to Term
First Claim
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1. A dual band transmitter comprising a lower band power amplifier for operating at a lower band frequency;

  • a higher band power amplifier for operating at a higher band frequency;

    the amplifiers each having an output;

    antenna means;

    combining means for coupling signals from said amplifiers to said antenna means;

    a lower band transmit path between the output of the lower band power amplifier and the combining means;

    a higher band transmit path between the output of the higher band power amplifier and the combining means;

    a switch which is switchable between a first and a second state, a stub having a first end coupled to the higher band transmit path and a second end coupled to the switch, whereby the second end of the stub is substantially closed or opened in dependence upon the state of the switch, and switch operating means for controlling the state of said switch so that, when said lower band power amplifier is active, said stub reduces substantially the propagation of spurious harmonics from the lower band transmit path in the higher band transmit path and said higher band power amplifier and, when said higher band power amplifier is active, said stub enables higher band frequency signals to propagate along said higher band transmit path from said higher band power amplifier to said antenna means.

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