Resonator devices and methods of fabricating resonator devices

According to various embodiments, there is provided a resonator device that includes a first interdigital transducer and a second interdigital transducer that is electrically connected to the first interdigital transducer. Both the first interdigital transducer and the second interdigital transducer are configured to resonate at a common frequency. At least one of an electrode width and an electrode pitch of the first interdigital transducer is different from the respective electrode width and/or electrode pitch of the second interdigital transducer such that spurious peaks of the resonator device are lower in amplitude as compared to spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

TECHNICAL FIELD

Various embodiments relate to resonator devices and methods of fabricating resonator devices.

BACKGROUND

While an ideal resonator should produce an output that includes a signal only at the target resonant frequency, the output of real resonators typically include spurious peaks. When multiple resonators are combined in a circuit or a device, the device output may include spurious peaks that interfere with a target mode of the device.

SUMMARY

According to various embodiments, there may be provided a resonator device including: a first interdigital transducer; and a second interdigital transducer electrically connected to the first interdigital transducer. Both the first interdigital transducer and the second interdigital transducer may be configured to resonate at a common frequency. At least one of an electrode width and an electrode pitch of the first interdigital transducer may be different from the respective electrode width(s) and electrode pitch(es) of the second interdigital transducer such that spurious peaks of the resonator device may be lower in amplitude as compared to spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

According to various embodiments, there may be provided a method of fabricating a resonator device. The method may include: providing a first interdigital transducer and a second interdigital transducer, wherein both the first interdigital transducer and the second interdigital transducer have a common resonant frequency; and electrically connecting the first interdigital transducer to the second interdigital transducer. At least one of an electrode width and an electrode pitch of the first interdigital transducer may be different from that of the second interdigital transducer such that spurious peaks of the resonator device may be lower in amplitude as compared to the spurious peaks of each of the first interdigital transducers and the second interdigital transducer.

According to various embodiments, there may be provided a method including: adjusting at least one of electrode pitches and electrode widths of a first interdigital transducer and a second interdigital transducer until each of the first interdigital transducer and the second interdigital transducer are configured to resonate at a common target frequency and are configured to produce spurious peaks at different frequencies; forming a resonator circuit comprising the first interdigital transducer electrically connected to the second interdigital transducer; determining a frequency response of the resonator circuit; and changing electrical connections between the first interdigital transducer and the second interdigital transducer until spurious peaks of the resonator circuit in the determined frequency response are lower in amplitude as compared to the spurious peaks of each of the first interdigital transducer and the second interdigital transducer. At least one of an electrode width and an electrode pitch of the first interdigital transducer may be different from the at least one of respective electrode width and electrode pitch of the second interdigital transducer.

DESCRIPTION

Embodiments described below in context of the devices are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, for example, a part of one embodiment may be combined with a part of another embodiment.

It will be understood that any property described herein for a specific device may also hold for any device described herein. It will be understood that any property described herein for a specific method may also hold for any method described herein. Furthermore, it will be understood that for any device or method described herein, not necessarily all the components or steps described must be enclosed in the device or method, but only some (but not all) components or steps may be enclosed.

The term “coupled” (or “connected”) herein may be understood as electrically coupled or as mechanically coupled, for example attached or fixed, or just in contact without any fixation, and it will be understood that both direct coupling or indirect coupling (in other words: coupling without direct contact) may be provided.

In order that the invention may be readily understood and put into practical effect, various embodiments will now be described by way of examples and not limitations, and with reference to the figures.

In the context of various embodiments, the phrase “resonator device” may be but is not limited to being interchangeably referred to as a “resonator circuit”.

According to various non-limiting embodiments, a resonator circuit may include a plurality of acoustic resonators with interdigital transducers (IDT) connected in series or in shunt. These acoustic resonators may have the same frequency for their target modes but may have different frequencies for their respective unwanted modes. The IDTs of these acoustic resonators may have, in general, different pitches and/or widths to decouple unwanted modes, while maintaining the same frequency for their target modes. The resonator circuit may achieve improved inter-device mode decoupling without requiring external decoupling components. The resonator circuit may be fabricated monolithically on a single chip.

FIG.1Aillustrates a top view of an interdigital transducer (IDT)100according to various non-limiting embodiments. The IDT100may be a type of resonator. The IDT100may convert electrical signals to vibrations, and may also convert vibrations to electrical signals. The IDT100may vibrate to generate acoustic waves. The IDT100may include a pair of interlocking comb-shaped array of electrodes110aand110b. WhileFIG.1shows the electrodes110aand110bas each having two fingers112, it should be understood that the electrodes110aand110bmay each have any quantity of fingers112as long as there are at least two fingers each for the electrodes110aand110b. Electrodes110and110bmay be at least substantially identical in a non-limiting embodiment. Key design parameters of the IDT100may include the pitch102(denoted herein as P) and the width104(denoted herein as W). The pitch102may be defined as the distance between two adjacent fingers112of the same electrode110aor110b, measured from the centers of the adjacent fingers112. The pitch102may determine a resonant wavelength of the IDT100. The width104may be defined as the width of the fingers112. The width104may be measured in a direction at least substantially parallel to the displacement between adjacent fingers112.

FIG.1Billustrates a cross-sectional view150of the IDT100, as cut across the line AA′ shown inFIG.1A. The IDT100may be formed on the base structure of a thin-film piezoelectric acoustic resonator. The IDT100may include a top electrode110, a piezoelectric layer120and a bottom electrode130. The top electrode110may include the interlocking, in other words, interdigitated, electrodes110aand110b. The piezoelectric layer120may be arranged between the top electrode110and the bottom electrode130. The top electrode110may be connected to an alternating electrical signal, for example, an alternating current (AC) signal such that the electrode110aand the electrode110bmay have opposing polarities at any one time. Consequently, the electric field between two adjacent fingers112may alternate, causing alternating regions of tensile and compressive strain in the piezoelectric layer120to generate acoustic waves. The bottom electrode130may be connected to ground, or a constant voltage (direct current).

FIG.2Aillustrates a graph200A showing the frequency response of a resonator. The graph200A has a horizontal axis202and a vertical axis204. The vertical axis204indicates the magnitude of the output electrical signal in Ohms. The horizontal axis202indicates frequency in Gigahertz (GHz). The graph200A shows a first peak220occurring at about 3.3 GHz which is the target mode noted as P1; a second peak222occurring at about 1.7 GHz, and a third peak224occurring at about 3.6 GHz. The second peak222and the third peak224are unwanted modes noted as P2 and P3 respectively.

FIG.2Billustrates a graph200B showing the frequency response of a resonator ladder circuit. The graph200B has a horizontal axis212and a vertical axis214. The vertical axis214indicates the signal power transferred from the input port to the output port of the resonator ladder circuit in decibels (dB). The horizontal axis212indicates frequency in GHz. The graph200B shows a first peak230occurring at about 3.3 GHz which corresponds to the target passband B1; a second peak232occurring at about 1.7 GHz which is an unwanted passband B2, and a third peak224occurring at about 3.6 GHz which is an unwanted passband B3. The unwanted passband B2 corresponds to the unwanted mode P2, while the unwanted passband B3 corresponds to the unwanted mode P3. In other words, the unwanted modes P2 and P3 may create the unwanted passbands B2 and B3. The unwanted passbands B2 and B3 may remain in the frequency spectrum of the resonator ladder circuit as they may not meet the out-of-band rejection requirement of the resonator ladder circuit. Subsequent paragraphs will describe resonator devices that may attenuate these unwanted passbands, in comparison with conventional resonator devices.

FIG.3illustrates a schematic view of a conventional resonator device300. The resonator device300may consist of a plurality of IDTs100aconnected in series. Each IDT100amay have the same width, for example W=1.9 um. Each IDT100amay also have the same pitch. The resonator device300may receive an input signal at an input port302, and generate an output signal based on the input signal at an output port304.

FIG.4illustrates a graph400showing the frequency response of the resonator device300. The graph400has a horizontal axis402and a vertical axis404. The vertical axis404indicates the signal power transferred from the input port302to the output port340in dB. The horizontal axis402indicates the operating frequency of the resonator device300in GHz. The graph400shows a first peak412occurring at about 3.3 GHz, a second peak410occurring at about 1.7 GHz, and a third peak414occurring at about 3.6 GHz. The peaks correspond to the modes discussed with respect toFIG.2A. The first peak412corresponds to the target mode P1; the second peak410corresponds to the unwanted mode P2, and the third peak414corresponds to the unwanted mode P3. In other words, the second peak410and the third peak414are spurious peaks. The first peak412has the largest value of −1.742 dB; whereas, the second peak410has a value of −10.942 dB and the third peak414has a value of −7.82 dB.

FIG.5illustrates a schematic view of a resonator device500according to various non-limiting embodiments. The resonator device500may differ from the conventional resonator device300, in that the plurality of IDTs that are connected in series may include IDTs100awith a first width, and IDTs100bwith a second width. The IDTs100aand100bmay be at least substantially similar, except that they have different widths. The IDTs100aand100bmay have at least substantially the same pitch, such that their resonant frequencies are at least substantially equal in a non-limiting embodiment. As an example, the first width may be 1.9 um, while the second width may be 2.0 um. The IDTs100aand the IDTs100bmay be arranged alternately, such that each IDT100ais immediately adjacent, in other words, directly connected, to an IDT100b.

FIG.6illustrates a graph600showing the frequency response of the resonator device500. The graph600shows a first peak612having a value of −1.667 dB at about 3.3 GHz, a second peak610having a value of −14.724 dB occurring at about 1.7 GHz, and a third peak614having a value of −10.244 dB occurring at about 3.6 GHz. The first peak612corresponds to the target mode P1; the second peak610corresponds to the unwanted mode P2, and the third peak614corresponds to the unwanted mode P3. As compared to the frequency response of the conventional resonator device300, in the frequency response of the resonator device500, the unwanted modes P2 and P3 are attenuated. The unwanted mode P2 is attenuated by about 3.78 dB while the unwanted mode P3 is attenuated by about 2.42 dB. The target mode P1 is unaffected, or even amplified by about 0.075 dB.

FIG.7illustrates a schematic view of a conventional resonator device700. The resonator device700may include a ladder filter circuit. The ladder filter circuit may include a first plurality of IDTs100aconnected in series like in the resonator device300, and a second plurality of IDTs100bconnected to the first plurality of IDTs100ain shunt, in other words, in parallel. The first plurality of IDTs may be referred herein as “series resonators”, while the second plurality of IDTs may be referred herein as “shunt resonators”. All of the IDTs100amay have the same width, for example a first width, W=1.9 um. All of the IDTs100amay also have the same pitch. All of the IDTs100cmay have the same width, which may be the same or may be different, from the first width. All of the IDTs100cmay also have the same pitch, which may be the same or may be different, from the pitch of the IDTs100a. The resonator device700may receive an input signal at an input port302, and generate an output signal based on the input signal at an output port304.

FIG.8illustrates a graph800showing the frequency response of the resonator device700. The graph800has a horizontal axis802and a vertical axis804. The vertical axis804indicates the signal power transferred from the input port302to the output port340in dB. The horizontal axis802indicates the operating frequency of the resonator device700in GHz. The graph800shows a first peak812occurring at about 3.3 GHz, a second peak810occurring at about 1.7 GHz, and a third peak814occurring at about 3.6 GHz. The peaks correspond to the passbands discussed with respect toFIG.2B. The first peak812corresponds to the target band B1; the second peak810corresponds to the unwanted passband B2, and the third peak814corresponds to the unwanted passband B3. The first peak812has the largest value of −1.835 dB, whereas the second peak810has a value of −11.769 dB and the third peak814has a value of −8.304 dB.

FIG.9illustrates a schematic view of a resonator device900according to various non-limiting embodiments. Like the resonator device700, the resonator device900may include a first plurality of IDTs connected in series and a second plurality of IDTs100cconnected in shunt to the first plurality of IDTs. The resonator device900may differ from the conventional resonator device700, in that the first plurality of IDTs may include IDTs100awith a first width, and IDTs100bwith a second width, like in the resonator device500. The IDTs100aand100bmay have at least substantially identical pitch in a non-limiting embodiment. All of the IDTs100cmay have the same width, which may be the same or may be different, from the first width or the second width. The resonator device900may receive an input signal at an input port302, and generate an output signal based on the input signal at an output port304. The resonant frequency of the shunt resonators, i.e. the second plurality of IDTs, may be lower than the resonant frequency of the series resonators, i.e. the first plurality of IDTs.

FIG.10illustrates a graph1000showing the frequency response of the resonator device900. The graph1000shows a first peak1012corresponding to the target passband B1 as having a value of −1.754 dB at about 3.3 GHz, a second peak1010corresponding to the unwanted passband B2 as having a value of −18.925 dB occurring at about 1.7 GHz, and a third peak1014corresponding to the unwanted passband B3 as having a value of −14.217 dB occurring at about 3.6 GHz. As compared to the frequency response of the conventional resonator device700, in the frequency response of the resonator device900, the unwanted passbands B2 and B3 are attenuated. The unwanted passband B2 is attenuated by more than 7 dB while the unwanted passband B3 is attenuated by about 6 dB. The target passband B1 is unaffected, or even amplified by about 0.08 dB.

FIG.11illustrates a schematic view of a resonator device1100according to various non-limiting embodiments. Like the resonator device900, the resonator device1100may include a first plurality of IDTs connected in series and a second plurality of IDTs connected in shunt to the first plurality of IDTs, and the first plurality of IDTs may include IDTs of different widths. The resonator device1100may differ from the resonator device900, in that the second plurality of IDTs may include IDTs100cwith a first pitch, and IDTs100dwith a second pitch. For example, the first pitch may be 4.8 um while the second pitch may be 4.74 um. The IDTs100cand100dmay have at least substantially the same width in a non-limiting embodiment. The width of the IDTs100cand100dmay be different from the widths of the first plurality of IDTs100aand100b. The width of the second plurality of IDTs100cand100dmay be less than the widths of the first plurality of IDTs100aand100b. For example, the width of the second plurality of IDTs100cand100dmay be 1.5 um. The IDTs100cand the IDTs100dmay be arranged alternately such that each IDT of the first plurality of IDTs may be directly connected to both IDT100cand IDT100d.

FIG.12illustrates a graph1200showing the frequency response of the resonator device1100. The graph1200shows a first peak1212corresponding to the target passband B1 as having a value of −1.751 dB at about 3.3 GHz, a second peak1210corresponding to the unwanted passband B2 as having a value of −20.506 dB occurring at about 1.7 GHz, and a third peak1214corresponding to the unwanted passband B3 as having a value of −14.217 dB occurring at about 3.6 GHz. Like the resonator device900, the resonator device1100may attenuate the unwanted passbands B2 and B3 without attenuating the target passband B1. As compared to the frequency response of the resonator device900, in the frequency response of the resonator device1100, the unwanted passband B2 is further attenuated by 1.58 dB while the target passband B1 and the unwanted passband B3 are unaffected. This shows that the unwanted passbands may be further attenuated by having a mix of shunt resonators of different pitches.

FIG.13illustrates a schematic view of a resonator device1300according to various non-limiting embodiments. The resonator device1300may be similar to the resonator device1100, except that the arrangement of the second plurality of IDTs100cand100dare reversed. The quantity of IDTs100cand100dmay also differ from that in the resonator device1100.

FIG.14illustrates a graph1400showing the frequency response of the resonator device1300. The graph1400shows a first peak1412corresponding to the target passband B1 as having a value of −1.398 dB at about 3.3 GHz, a second peak1410corresponding to the unwanted passband B2 as having a value of −18.254 dB occurring at about 1.7 GHz, and a third peak1414corresponding to the unwanted passband B3 as having a value of −15.121 dB occurring at about 3.6 GHz. Like the resonator device900, the resonator device1300may attenuate the unwanted passbands B2 and B3 without attenuating the target passband B1. As compared to the frequency response of the resonator device1100, in the frequency response of the resonator device1300, the unwanted passband B2 is amplified by about 2.25 dB, the unwanted passband B3 is further attenuated by about 0.90 dB while the target passband B1 is amplified by about 0.35 dB. This shows that the arrangement of the shunt resonators may also affect the attenuation of the unwanted passbands.

FIG.15illustrates a cross-sectional view of a resonator device1500according to various non-limiting embodiments. The resonator device1500may include a first IDT100aand a second IDT100b. Each of the first IDT100aand the second IDT100bmay be at least substantially identical, or at least similar in their physical composition. Each of the first IDT100aand the second IDT100bmay include a top electrode110, a piezoelectric layer120and a bottom electrode130, like described for the IDT100with respect toFIG.1B. The first IDT100aand the second IDT100bmay each be configured to resonate at the same frequency. The first IDT100aand the second IDT100bmay have different widths104, i.e. W1≠W2. The first IDT100aand the second IDT100bmay have the same pitch in a non-limiting embodiment. Alternatively, the first IDT100aand the second IDT100bmay have different pitches102, i.e. P1≠P2, but their resonant frequencies may still be at least substantially the same, by having different physical compositions. For example, the thickness(es) of at least one of the top electrode110, the piezoelectric layer120, and the bottom electrode130of the first IDT100amay be different from that of the second IDT100b. The first IDT100amay be connected to the second IDT100b, by at least one of electrical and acoustic connection1550. The electrical connection may be an electrically conductive material, which may be formed out of the same material as the top electrode110, for example, during the process of patterning the interlocking electrodes110aand110b. The acoustic connection may arise out of the first IDT100aand the second IDT100bbeing in close proximity, for example, being arranged on the same wafer, such that vibrations of the two IDTs may couple together.

FIG.16illustrates a cross-sectional view of a resonator device1600according to various non-limiting embodiments. The resonator device1600may be similar to the resonator device1500, except that the first IDT100aand the second IDT100bmay be conjoined at at least one of the piezoelectric layer120and the bottom electrode layer130. The electrical connection may be created, in the same process of creating the top electrode110. The top electrode110may be created by depositing an electrically conductive material such as a metal, over the piezoelectric layer120, and etching the electrically conductive material to form the interlocking electrodes110aand110b. The electrical connection may be formed in the same process of forming the interlocking electrodes110aand110b. The acoustic connection may arise out of the first IDT100aand the second IDT100bsharing the same piezoelectric layer120which vibrates in response to electrical signals.

According to various non-limiting embodiments, the resonator devices may operate in any one of Surface Acoustic Wave (SAW), Lamb or other lateral wave modes.

According to various non-limiting embodiments, the resonator devices may include, or may be part of, a filter, a transducer or other frequency-selective devices.

According to various non-limiting embodiments, a plurality of the resonator devices may be provided on a single wafer. Each resonator device may function as a filter, and the plurality of resonator devices may be connected to form a filter bank or a multiplexer. Each filter may be decoupled to the other filters in the bank by having its IDT pitch and width designed to reject the unwanted modes.

FIG.17illustrates a graph1700showing the frequency responses of two IDTs100that have different widths. The graph1700has a horizontal axis202and a vertical axis204. The graph1700includes a first plot1702and a second plot1704. The first plot1702is the frequency response of a first IDT having a pitch of 4.8 um and a width of 1.9 um. The second plot1704is the frequency response of a second IDT having a pitch of 4.8 um and a width of 2.0 um. The magnified diagram1712shows that the target modes of the first plot1702and the second plot1704coincide at around 3.3 GHz, corresponding to the target mode P1. The magnified diagrams1710and1712show that the unwanted modes P2 and P3 of the first plot1702and the second plot1704differ. In other words, the spurious peaks of IDTs100may be sensitive to the width of the IDTs. Therefore, the resonator devices described in the earlier paragraphs may be able to decouple the unwanted acoustic modes by having a mixture of IDTs that have different widths connected in series.

FIG.18illustrates a graph1800showing the frequency responses of two IDTs100that have different pitches. The graph1800includes a first plot1802and a second plot1804. The first plot1802is the frequency response of a first IDT having a pitch of 4.8 um and a width of 1.5 um. The second plot1804is the frequency response of a second IDT having a pitch of 4.74 um and a width of 1.5 um. The magnified diagram1812shows that the target modes of the first plot1802and the second plot1804coincide at around 3.3 GHz, corresponding to the target mode P1, and are about the same in amplitude. The magnified diagrams1810and1812show that the unwanted modes P2 and P3 of the first plot1802and the second plot1804differ. In other words, the spurious peaks of IDTs100may be sensitive to the pitch of the IDTs. Therefore, the resonator devices described in the earlier paragraphs may be able to decouple the unwanted acoustic modes, by having a mixture of IDTs that have different pitches connected in parallel.

According to various non-limiting embodiments, the resonator devices may decouple unwanted acoustic modes, by having a mixture of IDTs that have different pitches and different widths. These IDTs may be connected in series and/or in parallel.

FIG.19illustrates a graph1900that shows the dispersion diagram for various vibration modes in an IDT100. The graph1900has a horizontal axis1902and a vertical axis1904. The vertical axis1904indicates frequency in Megahertz (MHz). The horizontal axis1902indicates wave number in meters. Plot1910represents a fundamental mode vibration which is an antisymmetric wave, denoted as A0. Plot1912represents a fundamental mode vibration which is a symmetric wave, denoted as S0. Plot1914represents a first mode vibration which is an antisymmetric shear horizontal wave, denoted as A1(SH1). Plot1916represents a first mode vibration which is a transverse wave, denoted as S1(TE1). Plot1918represents a second mode vibration which is a shear horizontal wave, denoted as S2(SH2). The graph1900shows how the frequency of each wave varies according to changes in the wave number. Multiple modes may be supported for each given wavelength/wave as represented by the pitch/width of the IDT100. The graph1900shows that some of the modes are less sensitive to wave number changes. For example, the frequency of S1(TE1) is less sensitive to wave number change as compared to the frequency of S0.

FIG.20illustrates a flow diagram2000of a method for decoupling unwanted acoustic modes according to various non-limiting embodiments. The method may achieve the decoupling by connecting two or more acoustic resonators together to form a resonator circuit. The acoustic resonators may be IDTs100. The resulting resonator circuit may be any one of the resonator devices500,900,1100,1300,1500, or1600. The method may begin at a first step2002. From the first step2002, the method may proceed to step2004, in which geometries of at least two acoustic resonators may be designed to resonate at a common target frequency. Step2004may include selecting or varying various design parameters of the IDTs100. These design parameters may include pitch and width, as well as the materials and thicknesses of layers in the IDTs. Step2006may include simulating and observing the harmonic and/or modal responses of the acoustic resonators from step2004. Step2008may include determining based on the simulations from step2006, whether the at least two acoustic resonators have the same resonant frequency. If the acoustic resonators do not have the same target frequency, the method may proceed to step2004to design new geometries for the acoustic resonators until the acoustic resonators achieve the same resonant frequency. Otherwise, the method may proceed to step2010. Step2010may include determining based on the simulations from step2006, whether the unwanted frequencies, i.e. the frequencies of the spurious peaks of the acoustic resonators are different. If the acoustic resonators have spurious peaks at the same frequencies, the method may proceed to step2004to design new geometries for the acoustic resonators until the acoustic resonators have spurious peaks at different frequencies. Otherwise, the method may proceed to step2014.2014may include connecting the acoustic resonators designed at step2004, to form the resonator circuit. Step2016may include simulating the resonator circuit formed at step2016. Step2018may include determining based on the simulation results from step2016, whether vibrations at the target frequency band remain unaffected, i.e. not attenuated. If the target frequency band is attenuated, the method may proceed to step2014to change the circuit connection or configuration. For example, the acoustic resonators may be re-arranged as to their positions in the circuit, or may be re-connected from series to parallel or vice versa. Otherwise, the method may proceed to step2020. Step2020may include determining based on the simulation results from step2016, whether the unwanted frequencies are attenuated. If the unwanted frequencies are attenuated, the method may be completed in step2024. In other words, the resonator circuit formed in step2014may decouple unwanted acoustic modes. Otherwise, the method may proceed to step2014to change the circuit connection or configuration.

According to various non-limiting embodiments, a resonator device may include a first IDT and a second IDT that may be electrically connected to the first IDT. The resonator device may include, or may be part of, any one of the resonator devices500,900,1100,1300,1500, and1600. The first IDT and the second IDT may be configured to resonate at a common frequency. At least one of an electrode width and an electrode pitch of the first IDT may be different from the respective electrode width and/or electrode pitch of the second IDT. As a result of the difference in electrode pitch and/or width of the first IDT and the second IDT, spurious peaks of the resonator device may be lower in amplitude as compared to spurious peaks of each of the first IDT or the second IDT. The first IDT and the second IDT may be connected in series, like the IDTs100aand100bin the resonator devices500,900,1100and1300. The first IDT and the second IDT may be connected in parallel, like the IDTs100cor100dwith respect to the IDTs100aand100bin the resonator devices900,1100and1300. The first IDT and the second IDT may have a common bottom electrode, like described with respect to the resonator1600. The first IDT and the second IDT may have a common piezoelectric layer, also like described with respect to the resonator1600. The resonator device may further include a first plurality of IDTs connected in series and a second plurality of IDTs connected in shunt, like described with respect to the resonator devices900,1100and1300. Each IDT of the first plurality of IDTs may be configured to resonate at the common frequency. Each of the first IDT and the second IDT may be connected to the first plurality of IDTs in series, for example the first IDT may be one of the IDTs100aand the second IDT may be one of the IDTs100bin the resonator device900,1100or1300.

FIG.21illustrates a flow diagram2100of a method for fabricating a resonator device according to various non-limiting embodiments. Element2102may include providing a first IDT and a second IDT. The first IDT and the second IDT may be any one of the IDTs100a,100b,100c, and100d. Both the first IDT and the second IDT may have a common resonant frequency. Element2104may include electrically connecting the first IDT to the second IDT, for example, in series or in parallel. The first IDT may have at least one of an electrode width and an electrode pitch that is different from the corresponding electrode width and/or an electrode pitch of the second IDT, such that spurious peaks of the resonator device may be lower in amplitude as compared to the spurious peaks of each of the first interdigital transducers and the second interdigital transducer. In other words, the difference in pitch and/or width between the first IDT and the second IDT may result in attenuation of the spurious peaks, i.e. undesired signals. The resonator device that may be fabricated may include, or may be part of, any one of the resonator devices500,900,1100,1300,1500and1600.

FIG.22illustrates a flow diagram2200of a method according to various non-limiting embodiments. The method may include, or may be part of, the method described with respect toFIG.20. The method may be a method for decoupling unwanted modes in a resonator device. Element2202may include adjusting at least one of electrode pitches and/or electrode widths of a first IDT and a second IDT until each of the first IDT and the second IDT are configured to resonate at a common target frequency and are configured to produce spurious peaks at different frequencies. At least one of an electrode width and/or an electrode pitch of the first IDT may be different from the respective electrode width and/or electrode pitch of the second IDT. Element2204may include forming a resonator circuit that may include the first IDT electrically connected to the second IDT. Element2206may include determining a frequency response of the resonator circuit. Element2208may include changing electrical connections between the first IDT and the second IDT until spurious peaks of the resonator circuit in the determined frequency response are lower in amplitude as compared to the spurious peaks of each of the first IDT and the second IDT.

The following examples pertain to further embodiments.

Example 1 is a resonator device including: a first interdigital transducer; and a second interdigital transducer electrically connected to the first interdigital transducer; wherein both the first interdigital transducer and the second interdigital transducer are configured to resonate at a common frequency; and wherein at least one of an electrode width and an electrode pitch of the first interdigital transducer is different from the at least one of respective electrode width and electrode pitch of the second interdigital transducer such that spurious peaks of the resonator device are lower in amplitude as compared to spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

In example 2, the subject-matter of example 1 can optionally include that the second interdigital transducer is electrically connected to the first interdigital transducer in series.

In example 3, the subject-matter of any one of examples 1 or 2 can optionally include that the second interdigital transducer is electrically connected to the first interdigital transducer in parallel.

In example 4, the subject-matter of any one of examples 1 to 3 can optionally include that the first interdigital transducer and the second interdigital transducer have a common bottom electrode.

In example 5, the subject-matter of any one of examples 1 to 4 can optionally include that the first interdigital transducer and the second interdigital transducer have a common piezoelectric layer.

In example 6, the subject-matter of any one of examples 1 to 5 can optionally include: a first plurality of interdigital transducers connected in series and a second plurality of interdigital transducers connected in shunt; wherein each interdigital transducer of the first plurality of interdigital transducers is configured to resonate at the common frequency.

In example 7, the subject-matter of example 6 can optionally include that each of the first interdigital transducer and the second interdigital transducer are connected to the first plurality of interdigital transducers in series.

In example 8, the subject-matter of any one of examples 6 to 7 can optionally include that each interdigitated transducer of the second plurality of interdigitated transducers is configured to resonate at a lower frequency than the common frequency.

In example 9, the subject-matter of any one of examples 1 to 8 can optionally include that the first interdigital transducer and the second interdigital transducer are formed on a single wafer.

In example 10, the subject-matter of any one of examples 1 to 9 can optionally include that the first interdigital transducer is configured to produce spurious peaks at different frequencies than the second interdigital transducer.

Example 11 is a method of fabricating a resonator device, the method including: providing a first interdigital transducer and a second interdigital transducer, wherein both the first interdigital transducer and the second interdigital transducer have a common resonant frequency; and electrically connecting the first interdigital transducer to the second interdigital transducer; wherein at least one of an electrode width and an electrode pitch of the first interdigital transducer is different from that of the second interdigital transducer such that spurious peaks of the resonator device are lower in amplitude as compared to the spurious peaks of each of the first interdigital transducers and the second interdigital transducer.

In example 12, the subject-matter of example 11 can optionally include that providing the first interdigital transducer and the second interdigital transducer includes: forming a piezoelectric layer over a bottom electrode layer; depositing an electrode material over the piezoelectric layer; and patterning the electrode material to form a pair of interdigitated electrodes for each of the first interdigital transducer and the second interdigital transducer,

In example 13, the subject-matter of any one of examples 11 to 12 can optionally include that providing the first interdigital transducer and the second interdigital transducer includes: forming both the first interdigital transducer and the second interdigital transducer on a single wafer.

In example 14, the subject-matter of any one of examples 11 to 13 can optionally include: connecting a first plurality of interdigital transducers in series; connecting a second plurality of interdigital transducers in shunt; wherein each interdigital transducer of the first plurality of interdigital transducers is configured to resonate at the common frequency.

In example 15, the subject-matter of example 14 can optionally include: connecting each of the first interdigital transducer and the second interdigital transducer to the first plurality of interdigital transducers in series.

In example 16, the subject-matter of any one of examples 14 to 15 can optionally include that each interdigitated transducer of the second plurality of interdigitated transducers is configured to resonate at a lower frequency than the common frequency.

Example 17 is a method including: adjusting at least one of electrode pitches and electrode widths of a first interdigital transducer and a second interdigital transducer until each of the first interdigital transducer and the second interdigital transducer are configured to resonate at a common target frequency and are configured to produce spurious peaks at different frequencies; wherein at least one of an electrode width and an electrode pitch of the first interdigital transducer is different from the at least one of respective electrode width and electrode pitch of the second interdigital transducer; forming a resonator circuit including the first interdigital transducer electrically connected to the second interdigital transducer; determining a frequency response of the resonator circuit; and changing electrical connections between the first interdigital transducer and the second interdigital transducer until spurious peaks of the resonator circuit in the determined frequency response are lower in amplitude as compared to the spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

In example 18, the subject-matter of example 17 can optionally include that each the first interdigital transducer and the second interdigital transducer includes a top electrode layer, a piezoelectric layer and bottom electrode layer, wherein the method further includes: varying thickness of at least one of the top electrode layer, a piezoelectric layer and bottom electrode layer of both the first interdigital transducer and the second interdigital transducer, until spurious peaks of the resonator circuit in the determined frequency response are lower in amplitude as compared to the spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

In example 19, the subject-matter of any one of examples 17 to 18 can optionally include that each the first interdigital transducer and the second interdigital transducer includes a top electrode layer, a piezoelectric layer and bottom electrode layer, wherein the method further includes: varying thickness of at least one of the top electrode layer, a piezoelectric layer and bottom electrode layer of both the first interdigital transducer and the second interdigital transducer, until each of the first interdigital transducer and the second interdigital transducer are configured to resonate at a common target frequency and are configured to produce spurious peaks at different frequencies.

In example 20, the subject-matter of any one of examples 17 to 19 can optionally include: simulating harmonic responses of the first interdigital transducer and the second interdigital transducer to determine whether each of the first interdigital transducer and the second interdigital transducer are configured to resonate at the common target frequency and are configured to produce spurious peaks at different frequencies.