Multi-port mechanical resonating devices and related methods
Multi-port devices having multiple electrical ports are described, as are related methods. Some of the multi-port devices may have two input ports and two output ports, and may be driven differentially, in a single-ended mode, in a single-ended to differential mode, or in a differential to single-ended mode. The multi-port devices may include one or more transducers coupled to the electrical ports.
1. A device comprising:
a suspended mechanical resonating structure having a first surface and a second surface opposite the first surface;
a substrate coupled to the suspended mechanical resonating structure such that ends of the suspended mechanical resonating structure are free;
four electrical ports; and
four electrodes formed on the first surface, each one of the four electrodes being coupled to a respective one of the four electrical ports,
wherein the four electrical ports include two input ports configured as a differential input port and two output ports configured as a differential output port, and
wherein the mechanical resonating structure is formed of multiple layers, the layers comprising:
a first temperature compensating layer;
a second temperature compensating layer;
a conductive layer forming a conductive plane, wherein the conductive layer contacts the second temperature compensating layer; and
an active layer comprising a piezoelectric material, wherein the active layer contacts the conductive layer,
wherein the first and second temperature compensating layers compensate for temperature induced changes in a resonance frequency of the mechanical resonating structure,
wherein at least one of the first and second temperature compensating layers comprises Silicon Dioxide, and
wherein the piezoelectric material is Aluminum Nitride or Silicon.
2. The device of claim 1 , wherein
the substrate is coupled to sides of the suspended mechanical resonating structure via a plurality of anchors such that the anchors are substantially parallel to the ends of the suspended mechanical resonating structure.
3. The device of claim 2 , wherein a first electrode and second electrode of the four electrodes are configured to form at least part of a first transducer, and wherein a third electrode and fourth electrode of the four electrodes are configured to form at least part of a second transducer.
4. The device of claim 3 , wherein the first electrode is proximate the third electrode, and wherein the first and third electrodes are separated by a distance approximately equal to a multiple of λ/2, wherein λ is a wavelength of a Lamb wave supported by the mechanical resonating structure, and wherein the distance is measured from an approximate center of each of the first and third electrodes.
5. The device of claim 3 , wherein the first electrode is proximate the third electrode, and wherein the first and third electrodes are separated by a distance approximately equal to a multiple of λ4, wherein λ is a wavelength of a Lamb wave supported by the mechanical resonating structure, and wherein the distance is measured from an approximate center of each of the first and third electrodes.
6. The device of claim 2 , wherein the mechanical resonating structure has a substantially rectangular shape.
7. The device of claim 6 , wherein the mechanical resonating structure has beveled edges.
8. The device of claim 2 , wherein the mechanical resonating structure is substantially ring-shaped.
9. The device of claim 2 , wherein the mechanical resonating structure is substantially disc-shaped.
10. The device of claim 2 , wherein the mechanical resonating structure is substantially planar and is configured to support Lamb waves.
11. The device of claim 10 , wherein the mechanical resonating structure has a thickness value less than approximately two wavelengths of a resonant wave of the mechanical resonating structure.
12. The device of claim 11 , wherein the thickness value is less than approximately one wavelength of a resonant Lamb wave of the mechanical resonating structure.
13. The device of claim 1 , wherein the conductive layer is electrically grounded.
14. The device of claim 1 , wherein the conductive layer is electrically biased.
15. The device of claim 1 , wherein the conductive layer is electrically floating.
16. The device of claim 1 , wherein:
the mechanical resonating structure has a thickness less than approximately three wavelengths of a resonance frequency of the mechanical resonating structure;
the four electrodes are disposed on the first surface of the mechanical resonating structure;
two of the four electrodes are configured to receive a differential input signal; two of the four electrodes are configured to provide a differential output signal;
a first electrode of the two electrodes configured to receive a differential input signal is proximate to a second electrode of the two electrodes configured to receive a differential input signal;
a third electrode of the two electrodes configured to provide a differential output signal is proximate to a fourth electrode of the two electrodes configured to provide a differential output signal; and
the first and third electrodes are separated by a distance approximately equal to a multiple of λ/2, wherein λ is a wavelength of a Lamb wave supported by the mechanical resonating structure, and wherein the distance is measured from an approximate center of each of the first and third electrodes.
17. The device of claim 16 , wherein the thickness of the mechanical resonating structure is less than approximately one wavelength of the resonance frequency of the mechanical resonating structure.
18. The device of claim 1 , wherein
the mechanical resonating structure is substantially planar, the first surface is substantially planar, and the four electrodes are disposed on the first surface of the substantially planar suspended mechanical resonating structure;
and further comprising
a plurality of anchors coupling the mechanical resonating structure to the substrate,
wherein the plurality of anchors contact sides of the mechanical resonating structure and one or more of the anchors are substantially parallel to the ends of the mechanical resonating structure.
19. The device of claim 18 , wherein the device is configured to form at least part of a timing oscillator configured to generate a timing output signal.
20. The device of claim 18 , wherein the device is configured to form at least part of a filter.
21. The device of claim 18 , wherein the device is configured to form at least part of a gyroscope.
22. The device of claim 1 , wherein the second temperature compensating layer has a stiffness that increases with increases in temperature and the first temperature compensating layer has a stiffness that decreases with increases in temperature.
23. The device of claim 2 , wherein the suspended mechanical resonating structure comprises a base on which the four electrodes are formed, wherein the base has a first end having a first width and a second end having the first width, and wherein the base comprises a neck region having a smaller width than the first width.
24. The device of claim 1 , wherein the first temperature compensating layer has a lower acoustic loss than the second temperature compensating layer.