Apparatuses and methods involving suppression of spurious modes in resonator-based circuits
In certain examples, methods and apparatus are directed to a resonator-based circuit which, in operation, has an electrically-conductive band (“band”) at least partially surrounding a center electrode which includes the piezoelectric material of the circuit's resonator. In particular examples, the band acts to electrically load vibrations near resonance and consequently, spurious mode suppression is realized. In more particular example embodiments, the band maintains TE mode while eliminating lateral spurious tones, and in one application-specific example, the resonator-based circuitry and the electrical-conductive band are to provide of facilitate piezoelectric power conversion.
1 . An apparatus comprising:
resonator-based circuitry including a resonator having a center electrode; and
an electrical-conductive band (“band”), having an elongated contiguous region at least primarily surrounding the center electrode and having a width dimension that is smaller than a gap dimension defining a non-metalized separation between the band and the center electrode, to maintain TE mode and to suppress one or more spurious modes at least in part by electrically loading, during operation of the apparatus, piezoelectric material of the resonator.
2 . The apparatus of claim 1 , wherein the band is to suppress one or more spurious modes by providing substantially spurious-free operation of the apparatus, at a resonance frequency on the order of 1 MHz, without spreading out the one or more spurious mode or degrading a FoM (figure of merit) associated with the apparatus, and wherein the resonator has one or more center electrodes, including the center electrode, with the band being contiguously curved throughout the elongated contiguous region.
3 . The apparatus of claim 1 , wherein the band is to mitigate one or more spurious modes, caused by operation of the resonator-based circuitry, by sufficiently suppressing the one or more spurious modes during the operation of the apparatus, that if not suppressed the one or more spurious modes would degrade performance of the apparatus, and the gap dimension is smaller than the width dimension of the band by at least an order of magnitude, and wherein a crystal orientation of the resonator, the width dimension and the gap dimension are set to facilitate the TE mode being maintained or enhanced, while eliminating lateral spurious tones, to induce uniform vibration of the resonator.
4 . The apparatus of claim 1 , wherein the resonator is a piezoelectric-type resonator having a certain crystal orientation, the band has a shape that is round or oval, and the band and the certain crystal orientation are to increase coupling of the TE mode to induce uniform vibration of the resonator.
5 . The apparatus of claim 1 , wherein the band bears an irregular shape that is neither a round shape nor an oval shape, and a certain crystal orientation of the resonator and the band are to increase coupling of the TE mode to induce uniform vibration of the resonator.
6 . The apparatus of claim 1 , wherein the band is to provide an effective electrically loading along a perimeter that at least primarily surrounds the center electrode without any corners formed in the band, and each of the center electrode and the band has a common thickness.
7 . The apparatus of claim 1 , wherein the band is to provide a contiguous conductive perimeter that surrounds the center electrode entirely and that is
without any corners formed in the band, and
characterized as being without terminating ends.
8 . The apparatus of claim 1 , wherein the band has terminating ends, does not have any corners formed in the band, and is to provide a conductive perimeter primarily surrounding the center electrode.
9 . The apparatus of claim 1 , wherein the resonator included in the resonator-based circuitry is a piezoelectric acoustic resonator having at least one of Lithium and Niobate.
10 . The apparatus of claim 1 , wherein the one or more spurious modes are suppressed consistent with a spurious-suppressed region in a range from 0.50 MHz to 0.75 MHz.
11 . An apparatus comprising:
a piezoelectric resonator having at least one center electrode;
signal-processing circuitry, coupled to the piezoelectric resonator, to drive an application-specific circuit; and
a band, having an electrically-conductive contiguous region at least predominantly surrounding the at least one center electrode and having a width dimension that is smaller than a gap dimension defining a non-metalized separation between the band and the at least one center electrode, to maintain TE mode and to mitigate one or more spurious modes during operation of the apparatus at least in part by electrically loading piezoelectric material in the piezoelectric resonator.
12 . The apparatus of claim 11 , wherein the piezoelectric resonator is an acoustic resonator having at least one of Lithium and Niobate.
13 . The apparatus of claim 11 , wherein the signal-processing circuitry, the piezoelectric resonator and the band are to cooperatively operate to facilitate performance of the application-specific circuit, included as part of the apparatus, without adversely affecting operation of the application-specific circuit while the piezoelectric resonator operates at a resonance frequency on the order of 1 MHZ, and wherein the application-specific circuit includes at least one of: piezo-electric power conversion circuitry, RF (radio frequency) filter circuitry, one or more oscillators, and one or more transformers.
14 . The apparatus of claim 11 , wherein the at least one center electrode includes a certain center electrode and the band is a conductive ring that at least predominantly surrounds the certain center electrode to facilitate operation by suppressing spurious modes, and the gap dimension is smaller than the width dimension by at least an order of magnitude, and the width dimension and the gap dimension are set to facilitate the TE mode being maintained or enhanced while eliminating lateral spurious tones.
15 . The apparatus of claim 11 , wherein the electrically-conductive contiguous region of the band adequately surrounds a perimeter of the at least one center electrode to suppress the one or more spurious modes from adversely affecting a Q (quality) factor while maintaining a fractional suppressed region of at least 50% in a range from 50%-75%, and maintaining a spurious-suppressed region to a degree in a range from 0.50 MHz to 1.00 MHz, the width dimension of the band is smaller than the gap dimension by at least an order of magnitude, and the band is configured to enhance TE coupling and therein induce uniform vibration.
16 . The apparatus of claim 11 , wherein the band is connected to a reference node to electrically load piezoelectric material in the piezoelectric resonator.
17 . The apparatus of claim 11 , wherein the band includes a non-conductive separation with conductive material on opposite sides of the band, and with the band being connected to a reference node, as ground a rail or as a common terminal, on each of the opposing sides.
18 . The apparatus of claim 11 , wherein the piezoelectric material in the piezoelectric resonator is electrically loaded to reinforce TE coupling.
19 . The apparatus of claim 11 , wherein the band is to cause suppression of the one or more spurious modes based at least in part on an isotropic piezoelectric coefficient while causing suppression of an anisotropic coefficient, each of the coefficients being specific to the piezoelectric material in the piezoelectric resonator.
20 . The apparatus of claim 11 , wherein the band is to cause suppression of the one or more spurious modes while causing suppression of an anisotropic coefficient which is specific to the piezoelectric material in the piezoelectric resonator.
21 . A method for use with resonator-based circuitry including a resonator having a center electrode, the method comprising:
operating the resonator-based circuitry at a resonance frequency on the order of 1 MHz with an electrical-conductive band having a contiguously curved region at least predominantly surrounding a center electrode of the resonator-based circuitry; and
using the electrical-conductive band, while operating the resonator-based circuitry at the resonance frequency, having a width dimension that is smaller than a gap dimension defining a non-metalized separation between the electrical-conductive band and the center electrode, to maintain TE mode and to suppress one or more spurious modes at least in part by electrically loading piezoelectric material in the resonator.
22 . The method of claim 21 , wherein the resonator-based circuitry and the electrical-conductive band cooperatively interact by providing piezoelectric power conversion.
23 . The method of claim 21 , wherein the gap dimension is smaller than the width dimension by at least an order of magnitude, and the width dimension and the gap dimension are set to facilitate the TE mode being maintained or enhanced, while eliminating lateral spurious tones, to facilitate uniform vibration.