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FSK modulator using saw resonator with switchable capacitors

  • US 5,532,654 A
  • Filed: 06/01/1995
  • Issued: 07/02/1996
  • Est. Priority Date: 06/28/1994
  • Status: Expired due to Term
First Claim
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1. In combination with an amplifier for oscillation, an FSK modulator comprising:

  • a surface acoustic wave resonator connected to said amplifier;

    a switching circuit connected in series with said surface acoustic wave resonator, said switching circuit including one or more fixed-capacity capacitors and a semiconductor switch having first and second terminals and being capable of being set in an ON condition or an OFF condition wherein said semiconductor switch is respectively conductive or non-conductive between said first and second terminals and thereby causing one or a combination of said fixed-capacity capacitors to be connected in series with said surface acoustic wave resonator; and

    an input terminal connected to said semiconductor switch for receiving input signals for setting said semiconductor switch selectably in said ON or OFF condition.

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