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Voltage controlled oscillator, frequency synthesizer and communication apparatus

  • US 7,221,920 B2
  • Filed: 07/15/2004
  • Issued: 05/22/2007
  • Est. Priority Date: 07/24/2003
  • Status: Expired due to Fees
First Claim
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1. A voltage controlled oscillator, comprising:

  • a resonator configured to oscillate with an initial oscillation frequency during a starting period of oscillation and with a steady oscillation frequency during a steady state oscillation, the resonator including a film bulk acoustic resonator having a series resonance frequency higher than the steady oscillation frequency; and

    a negative resistance circuit connected to the resonator, configured to drive the resonator, the negative resistance circuit having a positive increment for reactance in the steady state oscillation compared with reactance in the starting period.

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