Resonator and device including the same
According to one embodiment, a resonator is disclosed. The resonator includes a vibrator and an attenuation mechanism. The attenuation mechanism selectively attenuates vibration of a spurious mode that is mechanically coupled to a first mode when the vibrator vibrates in the first mode.
1. A resonator comprising:
a substrate;
an anchor part provided on the substrate;
a spring part;
a vibrator disposed above the substrate and connected to the anchor part through the spring part; and
an attenuation mechanism configured to selectively attenuate vibration of a spurious mode that is mechanically coupled to a first mode when the vibrator vibrates in the first mode,
wherein:
the vibrator has an opening,
the anchor part is disposed in the opening when viewed from above the vibrator,
one end of the spring part is connected to an inner wall that defines the opening, another end of the spring part is connected to the anchor part, and
the attenuation mechanism comprises:
a first electrode provided on the substrate;
a second electrode provided on the substrate and disposed to face the first electrode through the anchor part; and
a controller configured to control a first capacitance between the vibrator and the first electrode and a second capacitance between the vibrator and the second electrode such that a difference between the first capacitance and the second capacitance falls in a certain range.
2. The resonator according to claim 1 , wherein:
the attenuation mechanism further comprises
a third electrode provided on the substrate and disposed on a side where the first electrode is provided; and
a fourth electrode provided on the substrate, disposed on a side where the second electrode is provided, and facing the third electrode through the anchor part, and
the controller comprises
an acquisition circuit configured to acquire the difference between the first capacitance and the second capacitance;
a differentiating circuit configured to differentiate a first output signal from the acquisition circuit; and
a voltage generation circuit configured to generate a control voltage based on a second output voltage from the acquisition circuit, the control voltage being to be applied between the third electrode and the fourth electrode to cause the difference between the first capacitance and the second capacitance falls in the certain range.
3. The resonator according to claim 1 , wherein the controller comprises a damper circuit connected to the first electrode and the second electrode.
4. The resonator according to claim 1 ,
wherein the attenuation mechanism comprises:
a first damper circuit connected to the first electrode; and
a second damper circuit connected to the second electrode.
5. The resonator according to claim 1 , wherein the attenuation mechanism is configured to reduce a Q factor of the spurious mode to one or less.
6. The resonator according to claim 1 , wherein the vibrator has a disk shape.
7. The resonator according to claim 1 , wherein the first mode includes an in-plane translation mode.
8. The resonator according to claim 7 , wherein the spurious mode includes an out-of-plane torsion mode, out-of-plane translation mode, or in-plane rotation mode.
9. A resonator comprising:
a substrate;
an anchor part provided on the substrate;
a spring part;
a vibrator disposed above the substrate and connected to the anchor part through the spring part; and
an attenuation mechanism configured to selectively attenuate vibration of a spurious mode that is mechanically coupled to a first mode when the vibrator vibrates in the first mode,
wherein the attenuation mechanism comprises:
a first piezoelectric film provided on a lower surface of the vibrator;
a second piezoelectric film provided on an upper surface of the vibrator and facing the first piezoelectric film;
a third piezoelectric film provided on the lower surface of the vibrator and disposed to face the first piezoelectric film through the anchor part;
a fourth piezoelectric film provided on the upper surface of the vibrator and facing the third piezoelectric film; and
a controller configured to control a first potential difference between the first piezoelectric film and the second piezoelectric film and a second potential difference between the third piezoelectric film and the fourth piezoelectric film such that a difference between the first potential difference and the second potential difference falls in a certain rage.
10. The resonator according to claim 9 , wherein the attenuation mechanism is configured to reduce a Q factor of the spurious mode to one or less.
11. The resonator according to claim 9 , wherein the vibrator has a disk shape.
12. The resonator according to claim 9 , wherein the first mode includes an in-plane translation mode.
13. The resonator according to claim 12 , wherein the spurious mode includes an out-of-plane torsion mode, out-of-plane translation mode, or in-plane rotation mode.
14. A resonator comprising:
a substrate;
an anchor part provided on the substrate;
a spring part;
a vibrator disposed above the substrate and connected to the anchor part through the spring part; and
an attenuation mechanism configured to selectively attenuate vibration of a spurious mode that is mechanically coupled to a first mode when the vibrator vibrates in the first mode,
wherein:
the vibrator has an opening,
the anchor part is disposed in the opening when viewed from above the vibrator,
one end of the spring part is connected to an inner wall that defines the opening, another end of the spring part is connected to the anchor part, and
the attenuation mechanism comprises:
a first lower electrode provided on the substrate;
a second lower electrode provided on the substrate and facing the first lower electrode through the anchor part;
a first upper electrode disposed above the vibrator and facing the first lower electrode;
a second upper electrode disposed above the vibrator to face the second lower electrode; and
a controller configured to control a first capacitance between the first lower electrode and the vibrator and a second capacitance between the first upper electrode and the vibrator, a third capacitance between the second lower electrode and the vibrator, and a fourth capacitance between the second upper electrode and the vibrator such that a difference between the first capacitance and the second capacitance falls in a certain range and a difference between the third capacitance and the fourth capacitance falls in a certain range.
15. The resonator according to claim 14 , wherein the attenuation mechanism is configured to reduce a Q factor of the spurious mode to one or less.
16. The resonator according to claim 15 , wherein the first mode includes an in-plane translation mode.
17. The resonator according to claim 16 , wherein the spurious mode includes an out-of-plane torsion mode, out-of-plane translation mode, or in-plane rotation mode.
18. The resonator according to claim 14 , wherein the vibrator has a disk shape.
19. A resonator comprising:
a substrate;
an anchor part provided on the substrate;
a spring part;
a vibrator disposed above the substrate and connected to the anchor part through the spring part; and
an attenuation mechanism configured to selectively attenuate vibration of a spurious mode that is mechanically coupled to a first mode when the vibrator vibrates in the first mode,
wherein:
the vibrator has an opening,
the anchor part is disposed in the opening when viewed from above the vibrator,
one end of the spring part is connected to an inner wall that defines the opening, another end of the spring part is connected to the anchor part, and
the attenuation mechanism comprises:
an outer circumferential electrode disposed away from the vibrator and disposed along a portion of an outer circumference of the vibrator when viewed from above the vibrator, and the outer circumferential electrode being electrically connected to the vibrator;
a first electrode facing a portion of the outer circumferential electrode;
a second electrode facing a portion of the outer circumferential electrode; and
a controller configured to control a first capacitance between the first electrode and the outer circumferential electrode and a second capacitance between the second electrode and the outer circumferential electrode such that a difference between the first capacitance and the second capacitance falls in a certain range.
20. The resonator according to claim 19 , further comprising a connecting electrode configured to connect the outer circumferential electrode and the vibrator.