Radio frequency transmitter having switched mode power supply

  • US 5,831,548 A
  • Filed: 10/17/1997
  • Issued: 11/03/1998
  • Est. Priority Date: 06/05/1995
  • Status: Expired due to Term
First Claim
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1. A hand-held radio frequency transmitter for use in generating a coded radio frequency transmission comprising:

  • a switched mode power supply energizable by a battery for delivering a pre-selected, uniform potential greater than the potential of the battery to an oscillator;

    an oscillator coupled to be driven by the switched mode power supply; and

    a modulator for controlling operation of the oscillator to cause the oscillator to be modulated by coded signals and for controlling operation of the switched mode power supply for enabling and disabling current flowing therethrough;

    wherein said switched mode power supply is coupled in a feedback loop with said modulator wherein the feedback loop signals said modulator when the switched mode power supply reaches the pre-selected, uniform potential effective for minimizing transmitter frequency drift.

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