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High frequency receiving apparatus

  • US 5,600,680 A
  • Filed: 09/08/1995
  • Issued: 02/04/1997
  • Est. Priority Date: 06/01/1993
  • Status: Expired due to Fees
First Claim
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1. A high frequency receiving apparatus comprising:

  • a mixer for mixing a local oscillation signal with a high frequency input signal to obtain an intermediate frequency signal;

    a local oscillation device for controlling a frequency of an oscillator with a PLL system on the basis of an oscillation frequency of a reference solid-state oscillation element and for sending said local oscillation signal to said mixer;

    a detection oscillator for generating an oscillation signal for picture synchronous detection;

    a picture synchronous detector for producing a detection output having a specific phase difference from said oscillation signal of said detection oscillator based upon said intermediate frequency signal;

    a phase comparator for comparing a phase difference between said intermediate frequency signal and said oscillation signal of said detection oscillator;

    a variable capacitive element equivalently connected in parallel to said reference solid-state oscillation element of said local oscillation device for converting a voltage change into a capacitance change; and

    a voltage feedback device for applying an output voltage of said phase comparator to said variable capacitive element.

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