Apparatus and method for extending tuning range of electro-acoustic film resonators
AssigneeNational Semiconductor Corporation
InventorDieter Scherer
Life of this patent
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Abstract
A tuning circuit for adjusting an oscillation frequency of an oscillator circuit. The tuning circuit comprises a film bulk acoustic wave resonator (FBAR) having a series resonance frequency and a parallel resonance frequency, and an inductor coupled in series or parallel with the film bulk acoustic wave resonator. The series connection of the inductor and FBAR decreases the series resonance frequency. The parallel connection of the inductor and the FBAR increases the parallel resonance frequency. The tuning circuit further comprises a varactor coupled in series or parallel with the inductor and the FBAR combination. The varactor tunes the oscillation frequency over the increased tuning range.
Claims20
For use in an oscillator circuit, a tuning circuit for adjusting an oscillation frequency of said oscillator circuit comprising:
- a film bulk acoustic wave resonator having a series resonance frequency and a parallel resonance frequency associated therewith;
- an inductor coupled in parallel between a first input and a second input of said film bulk acoustic wave resonator, said parallel connection of said inductor and said film bulk acoustic wave resonator operable to increase said parallel resonance frequency;
- and
- a tuning capacitor coupled in parallel with said parallel connection of said inductor and said film bulk acoustic wave resonator, said tuning capacitor operable to tune said oscillation frequency between said increased parallel resonance frequency and said series resonance frequency.
A communication device comprising:
- at least one of:
- transmit path circuitry operable to receive an uplink data stream and upconvert said uplink data stream to a higher frequency signal for subsequent transmission through a communication channel;
- and
- receive path circuitry operable to receive a high-frequency signal from said communication channel and downconvert said high-frequency signal to a lower frequency downlink data stream;
- an oscillator circuit associated with said at least one of said transmit path circuitry and said receive path circuitry, said oscillator circuit comprising a tuning circuit for adjusting an oscillation frequency of said oscillator circuit, wherein said tuning circuit comprises:
- a film bulk acoustic wave resonator having a series resonance frequency and a parallel resonance frequency associated therewith;
- an inductor coupled in parallel between a first input and a second input of said film bulk acoustic wave resonator, said parallel connection of said inductor and said film bulk acoustic wave resonator operable to increase said parallel resonance frequency;
- and
- a tuning capacitor coupled in parallel with said parallel connection of said inductor and said film bulk acoustic wave resonator, said tuning capacitor operable to tune said oscillation frequency between said increased parallel resonance frequency and said series resonance frequency.
For use in an oscillator containing a film bulk acoustic wave resonator (FBAR) having a series resonance frequency and a parallel resonance frequency associated therewith, a method of increasing the tuning range of the FBAR comprising the steps of:
- increasing the parallel resonance frequency by coupling an inductor in parallel between a first input and a second input of the FBAR;
- and
- coupling a tuning capacitor in parallel with the parallel connection of the inductor and the film bulk acoustic wave resonator, wherein the tuning capacitor is operable to tune the oscillation frequency between the increased parallel resonance frequency and the series resonance frequency.
Dependencies are inferred from the claim text.