Dual-mode surface acoustic wave (DMS) filter with modulated interdigital transducer

Abstract

An apparatus for a dual-mode surface acoustic wave (SAW) filter having a modulated interdigital transducer is disclosed. In an example aspect, the apparatus includes a dual-mode surface acoustic wave filter having at least one interdigital transducer. The interdigital transducer includes a first bus, a second bus, and a plurality of fingers extending from the first bus toward the second bus. The plurality of fingers includes a first set of fingers having a first spatial property. The plurality of fingers also includes a second set of fingers having a second spatial property different from the first spatial property. The second spatial property includes at least two fingers of the second set of fingers positioned adjacent to each other.

Description

Technical Field

[0001] This disclosure relates generally to wireless transceivers and other components employing filters, and more specifically to implementing a dual-mode surface acoustic wave (DMS) filter having multiple sets of fingers that are modulated differently. Background Technology

[0002] Electronic devices use radio frequency (RF) signals to transmit information. These RF signals enable users to talk to friends, download information, share pictures, remotely control home appliances, and receive GPS information, to name just a few consumer-oriented examples. To transmit or receive RF signals within a given frequency band, electronic devices can use filters to allow signals within the band to pass and suppress (e.g., reduce) interference or noise at frequencies outside the band. However, designing filters that provide filtering for RF applications, including those utilizing frequencies above 100 MHz, can be challenging. Summary of the Invention

[0003] An apparatus for implementing a dual-mode surface acoustic wave (DMS) filter is disclosed, the DMS filter having multiple sets of fingers modulated differently. Each set of fingers may be part of a different region, wherein at least one region has modulated fingers. For example, a corresponding transition region of the dual-mode DMS filter may include multiple sets of fingers respectively located at adjacent outer edges of two corresponding interdigital transducers. Each corresponding set of fingers may have different spatial properties. Within a given interdigital transducer, the two sets of fingers may also have different spatial properties. Examples of such different spatial properties include spacing, metallization ratio, number of fingers per unit cell, unit width, and whether a particular bus has adjacent fingers, and whether there are no intermediate fingers from the opposing bus between adjacent fingers. The corresponding spatial properties on at least a portion of each set of fingers may be substantially uniform. In some specific embodiments, these spatial properties may be adjusted to modulate the fingers differently within at least one interdigital transducer to change the filter characteristics. For example, by modulating the fingers as described herein, a two-mode surface acoustic wave filter can be constructed to have at least one steeper skirt in the filter's frequency response. A steeper skirt allows adjacent frequency bands to be closer together without causing interference.

[0004] In an example, an apparatus for filtering is disclosed. The apparatus includes a dual-mode surface acoustic wave (SAW) filter, which includes at least one interdigital transducer. The at least one interdigital transducer includes a first bus, a second bus, and a plurality of fingers extending from the first bus toward the second bus. The plurality of fingers includes a first set of fingers having a first spatial property. The plurality of fingers also includes a second set of fingers having a second spatial property different from the first spatial property. The second spatial property includes at least two fingers in the second set of fingers being positioned adjacent to each other.

[0005] In an example, a method for manufacturing a dual-mode surface acoustic wave (SAW) filter is disclosed. The method includes providing a first set of fingers for at least one interdigital transducer of the dual-mode SAW filter. The first set of fingers extends from a first busbar of the at least one interdigital transducer toward a second busbar of the at least one interdigital transducer, wherein the first set of fingers has a first spatial property. The method also includes providing a second set of fingers for the at least one interdigital transducer of the dual-mode SAW filter. The second set of fingers extends from the first busbar toward the second busbar, wherein the second set of fingers has a second spatial property different from the first spatial property. The second spatial property includes at least two fingers in the second set of fingers being positioned adjacent to each other.

[0006] In an example, an apparatus for filtering is disclosed. The apparatus includes a dual-mode surface acoustic wave (SAW) filter comprising at least one interdigital transducer. The at least one interdigital transducer includes a first region having a plurality of fingers arranged such that fingers from different busbars of the at least one interdigital transducer alternate, wherein the plurality of fingers in the first region have a first spacing. The at least one interdigital transducer also includes a second region having a plurality of other fingers arranged such that at least two adjacent fingers extending from the same busbar of the at least one interdigital transducer have a second spacing different from the first spacing. Attached Figure Description

[0007] Figure 1 An example operating environment for a two-mode surface acoustic wave filter with a modulated interdigital transducer (IDT) is illustrated.

[0008] Figure 2 An example wireless transceiver is shown, which includes a dual-mode surface acoustic wave filter that may have a modulated interdigital transducer.

[0009] Figure 3 An example component of a two-mode surface acoustic wave filter that can have a modulated interdigital transducer is shown.

[0010] Figure 4-1An example implementation of a dual-mode surface acoustic wave filter using a stack of thin-film surface acoustic wave filters is illustrated.

[0011] Figure 4-2 An example implementation of a dual-mode surface acoustic wave filter using a high-quality temperature-compensated surface acoustic wave filter stack is illustrated.

[0012] Figure 5 An example electrode structure for a two-mode surface acoustic wave filter that may include a modulated interdigital transducer is illustrated.

[0013] Figure 6 An example of a modulated interdigital transducer is illustrated, comprising multiple regions having multiple sets of fingers, the multiple regions including regions having adjacent fingers.

[0014] Figure 7 An example of two modulated interdigital transducers is illustrated, comprising multiple regions with multiple sets of fingers, wherein each interdigital transducer includes a region with adjacent fingers.

[0015] Figure 8 Example graphs depicting two example transfer functions are shown, one of which can be generated by implementing various aspects of a two-mode surface acoustic wave filter with a modulated interdigital transducer.

[0016] Figure 9 Three example cell arrangements for interdigital transducers used to modulate dual-mode surface acoustic wave filters are illustrated.

[0017] Figure 10 Examples Figure 9 Example graphs of two aspects of three example modulated interdigital transducers with three example unit arrangements.

[0018] Figure 11 An example dual-mode surface acoustic wave filter including three example modulated interdigital transducers is illustrated.

[0019] Figure 12 Examples Figure 11 An enlarged view of a portion of an example dual-mode surface acoustic wave filter, where each of the two interdigital transducers has been divided into two sub-interdigital transducers.

[0020] Figure 13 Examples Figure 11 Example curves for two aspects of an example dual-mode surface acoustic wave filter.

[0021] Figure 14 Examples Figure 11 and Figure 12 Example graphs depicting two aspects of an example first modulated interdigital transducer.

[0022] Figure 15 Examples Figure 11 and Figure 12 Example graphs depicting two aspects of an example second modulated interdigital transducer.

[0023] Figure 16 This is a flowchart illustrating an example process for manufacturing a two-mode surface acoustic wave filter with a modulated interdigital transducer. Detailed Implementation

[0024] To transmit or receive radio frequency signals within a given frequency band, electronic devices can use filters to allow signals within the band to pass and suppress (e.g., attenuate) interference or noise with frequencies outside the band. Electroacoustic devices (e.g., “acoustic filters” or “microacoustic filters”) can be used in many applications to filter high-frequency signals, such as those with frequencies greater than 100 MHz. Acoustic filters are tuned to allow certain frequencies (e.g., frequencies within their passband) to pass and attenuate other frequencies (e.g., frequencies outside their passband, such as frequencies within their stopband). Using piezoelectric materials as the vibrating medium, acoustic filters operate by transforming an electrical signal wave propagating along an electrical conductor into an acoustic wave (e.g., an acoustic signal wave) formed across the piezoelectric material, which can filter specific frequencies. The acoustic wave is then converted back to an electrically filtered signal. Acoustic filters can include electrode structures that transform or convert between electrical waves and acoustic waves.

[0025] Sound waves are formed across piezoelectric materials, and their speed is significantly less than that of electromagnetic waves. Generally, the speed of a wave is proportional to its wavelength. Therefore, after converting an electrical signal wave into a sound signal wave, the wavelength of the sound signal wave is significantly smaller than that of the electrical signal wave. This smaller wavelength of the sound signal wave allows for the use of smaller filter devices to perform filtering. This permits the use of acoustic filters in space-constrained devices, including portable electronic devices such as mobile phones.

[0026] However, designing a broadband acoustic filter with a compact design that also provides a sufficiently steep skirt for the filter's frequency response can be challenging. The frequency response of a bandpass filter, plotted as attenuation versus frequency, can resemble the shape of the letter "n". The top of the "n" roughly corresponds to the passband of the bandpass filter. The frequencies outside the "n" roughly correspond to the stopband of the filter. The two sides of the "n" typically slope in the transition region between the lower and upper parts of the passband and stopband. This sloping portion of the graph is sometimes referred to as the skirt of the frequency response.

[0027] Generally, a steeper skirt means a more abrupt change between the frequencies that pass through and those that are blocked. Therefore, a steeper skirt offers more options for using near frequencies that are "just outside" the filter's passband. Electronic devices can use multiple frequency bands, including the band used for the passband of a given filter. Other frequency bands can be above or below the passband, one closer to the passband than the other. If the closer frequency band is above the passband of a given filter, the high-frequency side (or "right") of the skirt can be the focus for providing a steep skirt to avoid interband interference. On the other hand, if the closer frequency band is below the passband of a given filter, the low-frequency side (or "left") of the skirt can be the focus for providing a steep skirt to avoid interband interference.

[0028] Another factor that can affect the shape or slope of the skirt portion of the frequency response is the acoustic material used in the SAW filter. For example, lithium niobate (LiNbO3)122 (LN122) is a substrate used in SAW filters with relatively low speeds. This lower speed allows the filter to be relatively small. However, for the LN122 SAW filter, the reflection sign of the electrodes is positive, compared to most materials currently used in SAW filters. This positive reflection sign causes the resonant frequency of a uniform grid strip with, for example, two fingers per wavelength (λ) to appear at the upper stopband edge (or right skirt). Most materials used in SAW filters to date have a negative reflection sign for the electrodes; therefore, their resonant frequencies are at the lower stopband edge (or left skirt).

[0029] In filters such as dual-mode SAW (DMS) filters (or sometimes called dual-mode) filters, the interdigital transducers' fingers are periodically arranged such that their resonant frequencies occur within the passband. Therefore, the upper stopband edge of each transducer in a DMS on a positively reflecting substrate material lies above the left skirt of the filter. DMS filters are advantageous due to their small size, but they are primarily used for receiver (Rx) filters because their power endurance is less than that of ladder filters.

[0030] In most systems, the Rx band is higher than the corresponding Tx band. Therefore, the Rx filter can be designed to provide a steep left skirt. Generally speaking, providing a steep skirt involves creating a long delay time for the signal. In the DMS track, the intracavity delay time at the transition between two interdigital transducers, each with two fingers per wavelength, is insufficient due to the stopband of the interdigital transducers at higher frequencies, resulting in insufficient wave penetration into the interdigital transducers. As used herein, employing two fingers per wavelength is referred to as the standard finger arrangement or normal modulation of interdigital transducers.

[0031] In some methods, the delay in the cavity between two interdigital transducers with a standard finger arrangement can be increased by increasing the distance between them. However, this additional space is not used for any excitation. Therefore, the track length is increased to obtain a pre-spaced impedance. In an alternative method, a modified metallization ratio can be achieved, where the reduced (e.g., minimized) strip reflectivity is located near the transition region between the interdigital transducer connected to the input port and the interdigital transducer connected to the output port. However, limitations on the metallization ratio due to manufacturing constraints typically do not allow for the necessary reduction.

[0032] A DMS filter with a steep left skirt can be produced using a material with negative reflection symbols and electrodes, because the stopband of such interdigital transducers within the DMS is significant above the left skirt. This contrasts with substrate materials with positive reflection symbols and electrodes, such as LN122. In the example implementation, for materials with positive reflection symbols, the stopband formed by the fingers near the transition between the two interdigital transducers shifts in a manner that does not prevent the necessary cavity length. Therefore, modulation of these fingers similarly does not prevent the necessary delay time that may produce a steep skirt. Such modulation of the interdigital transducers allows the stopband of the interdigital transducers to shift from the frequency with the maximum excitation.

[0033] In some specific implementations, the interdigital transducer is modulated using cells of length nλ and 2n+1 fingers within each cell, where λ corresponds to the wavelength targeted by the filter. Within each cell, the fingers are connected to alternating buses. This linear arrangement of such cells produces spatial properties of the fingers (e.g., property geometry), where, after a length nλ, two adjacent fingers from two different cells are connected at the same bus. These two adjacent fingers are not separated by an intermediate finger from an opposing bus. Examples of such repeating cellular arrangements are described overall in this paper, including references. Figure 9 Specific examples, where n=2, n=3 and n=4.

[0034] In this type of cell, the finger period is nλ / (2n+1), therefore, compared to a normal finger cell with a finger period of λ / 2, the corresponding stopband is shifted towards higher frequencies. Compared to a larger... n Compared to the value, the relatively smaller one in this formula n This value results in a relatively small finger cycle. Manufacturing constraints regarding the minimum structure width may influence design considerations. A relatively large... n This value reduces the frequency shift between the maximum excitation below the stopband and the stopband boundary. Therefore, n A reasonable upper limit can be derived from the stopband width. For example, the higher the reflectivity of each band, and therefore the wider the stopband, the greater the maximum effective reflectivity. n The lower the value, the better.

[0035] A DMS filter with only interdigital transducers fully modulated according to the cellular scheme described above may not be suitable for broadband filtering. This is because, in this case, the cavity is formed by reflectors at both ends of the DMS track. A very long cavity can result in a very small frequency distance between adjacent frequency dips. Furthermore, the unnecessarily long acoustic delay leads to increased insertion attenuation due to acoustic propagation losses. Therefore, the interdigital transducers of a DMS filter can include some fingers modulated based on the described cellular scheme for generating adjacent fingers, and can also include other fingers modulated differently, such as two standard fingers per wavelength.

[0036] In an example implementation of the DMS level, the DMS filter comprises three interdigital transducers arranged in symmetrical orbits, each with reflectors at both ends. In this tri-interdigital transducer DMS filter, each interdigital transducer includes a region with two fingers per wavelength and a region with modulation units, as described herein. In the example, the modulation regions of the interdigital transducers face each other. To achieve better phase relationships, adjustments can be made at the boundaries of these modulation regions within the interdigital transducers and at the boundaries between the interdigital transducers. For this purpose, the modulation region of the transducer can “begin” with an incomplete modulation unit on the side of the modulation region adjacent to the standard finger region.

[0037] In some cases, such as for relatively long modulation unit regions, several strips may be removed at the ends facing adjacent interdigital transducers. To create a smoother, more gradual spacing distribution, adjustments are made near the ends of the identified regions to result in chirps with varying spacing. Some (e.g., two or more) floating or grounded metal strips may also be positioned between two adjacent interdigital transducers connected to different electrical ports (e.g., an input port and an output port).

[0038] In these ways, a dual-mode surface acoustic wave (SAW) filter can include at least one interdigital transducer with different regions. The different regions are modulated differently. In one example aspect, one region has normally modulated fingers, where each cell is one wavelength wide and has two fingers. Another region has modulated fingers such that each cell has a width that is a multiple of the wavelength and includes an odd number of fingers based on that multiple. For example, the spacing can also vary between the two regions. Using these or other described techniques, the steepness of the skirt can be increased. For materials with positive reflection symbols having electrodes, the left skirt can be made steeper. Furthermore, for materials with negative reflection symbols having electrodes, the right skirt can be steeper. This allows the wireless transceiver to be designed to operate in frequency bands that are closer together along the electromagnetic spectrum.

[0039] Figure 1An example environment 100 for operating a dual-mode surface acoustic wave filter with a modulated interdigital transducer is illustrated. In environment 100, an example computing device 102 communicates with a base station 104 via a wireless communication link 106 (wireless link 106). In this example, the computing device 102 is depicted as a smartphone. However, the computing device 102 can be implemented as any suitable computing or electronic device, such as a modem, cellular base station, broadband router, access point, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, wearable computer, server, network-attached storage (NAS) device, smart appliance or other Internet of Things (IoT) device, medical device, vehicle-based communication system, radar, radio device, etc.

[0040] Base station 104 communicates with computing device 102 via wireless link 106, which can be implemented as any suitable type of wireless link. Although depicted as a cellular network tower, base station 104 can represent or be implemented as another device, such as a satellite, server equipment, terrestrial television broadcasting tower, access point, peer-to-peer device, mesh network node, etc. Therefore, computing device 102 can communicate with base station 104 or another device via a wireless connection.

[0041] Wireless link 106 may include a downlink transmitting data or control information from base station 104 to computing device 102, an uplink transmitting other data or control information from computing device 102 to base station 104, or both downlink and uplink. Wireless link 106 may be implemented using any suitable communication protocol or standard, such as (e.g., 2G, 3G, 4G, 5G, or 6G) cellular (e.g., IEEE 802.11, e.g., Wi-Fi). ® ); IEEE 802.15 (e.g., Bluetooth) ® ); IEEE 802.16 (e.g., WiMAX) ® ); etc. In some implementations, the wireless link 106 may provide power wirelessly, and the base station 104 or computing device 102 may include a power source.

[0042] As shown in the figure, computing device 102 includes an application processor 108 and a computer-readable storage medium 110 (CRM 110). The application processor 108 may include any type of processor, such as a multi-core processor, that executes processor-executable code stored in the CRM 110. The CRM 110 may include any suitable type of data storage medium, such as volatile memory (e.g., random access memory (RAM)), non-volatile memory (e.g., flash memory), optical media, magnetic media (e.g., disk), etc. In the context of this disclosure, the CRM 110 is implemented to store instructions 112, data 114, and other information of computing device 102, and therefore does not include transiently propagated signals or carrier waves.

[0043] The computing device 102 may also include an input / output port 116 (I / O port 116) and a display 118. The I / O port 116 enables data exchange or interaction with other devices, networks, or users. The I / O port 116 may include a serial port (e.g., a Universal Serial Bus (USB) port), a parallel port, an audio port, an infrared (IR) port, a user interface port such as a touchscreen, etc. The display 118 displays graphics from the computing device 102, such as a user interface associated with an operating system, program, or application. Alternatively or additionally, the display 118 may be implemented as a display port or virtual interface through which the graphical content of the computing device 102 is displayed.

[0044] The wireless transceiver 120 of computing device 102 provides connectivity to a suitable network and other electronic devices connected thereto. The wireless transceiver 120 can facilitate communication over any suitable type of wireless network, such as a wireless local area network (WLAN), peer-to-peer (P2P) network, mesh network, cellular network, ultra-wideband (UWB) network, wireless wide area network (WWAN), and / or wireless personal area network (WPAN). In the context of example environment 100, the wireless transceiver 120 enables computing device 102 to communicate with base station 104 and the network connected thereto. However, the wireless transceiver 120 can also enable computing device 102 to communicate "directly" with other devices or networks.

[0045] Wireless transceiver 120 includes circuitry and logic for transmitting and receiving communication signals via antenna 122. Components of wireless transceiver 120 may include amplifiers, switches, mixers, analog-to-digital converters, filters, etc., for conditioning communication signals (e.g., for generating or processing signals). Wireless transceiver 120 may also include logic for performing in-phase / quadrature (I / Q) operations such as synthesis, encoding, modulation, decoding, demodulation, etc. In some cases, components of wireless transceiver 120 are implemented as separate transmitter and receiver entities. Additionally or alternatively, wireless transceiver 120 may be implemented using multiple or different parts to achieve corresponding transmit and receive operations (e.g., separate transmit and receive chains). Generally, wireless transceiver 120 processes data and / or signals associated with data transmitted from computing device 102 via antenna 122.

[0046] exist Figure 1 In the example shown, the wireless transceiver 120 includes at least one dual-mode surface acoustic wave (SAW) filter 124 (DMS filter 124). The DMS filter 124 can be implemented, for example, as a longitudinally coupled dual-mode SAW (LDMS) filter. The DMS filter 124 can be implemented using, for example, a thin-film SAW (TFSAW) filter stack or a high-quality temperature-compensated SAW (HQTC) filter stack. Generally, the DMS filter 124 can excite at least two wave modes. In the example embodiment, the DMS filter 124 excites a dominant wave mode (e.g., a plate mode) and a cavity mode.

[0047] The dual-mode surface acoustic wave filter 124 includes at least two interdigital transducers 126 and at least one transition region 128. The transition region 128 may exist between two adjacent interdigital transducers 126, across two adjacent interdigital transducers 126, or some combination thereof. Additionally or alternatively, although the rectangle representing the transition region 128 may be... Figure 1 The interdigital transducers 126 are depicted separately, but each interdigital transducer 126 may include at least one transition region 128. Regarding Figure 3 Examples of the interdigital transducer 126 and the transition region 128 are further described.

[0048] Each interdigitated transducer 126 may include at least one spatial attribute 130. Furthermore, the at least one spatial attribute 130 of each interdigitated transducer 126 may be substantially uniform (e.g., substantially stable, constant, or static) over a portion of the interdigitated transducer 126 (such as the transition region 128). Generally, the term "substantially uniform" can mean that the spatial attribute varies by less than ±1% over a portion of a given region (e.g., over at least two pairs of adjacent fingers or over two cells within the transition region 128). For example, the value of the spatial attribute may vary by ±1%, ±0.75%, ±0.50%, or less over a specific portion of the transition region 128. This amount of variation can explain minor differences caused by process variations.

[0049] Examples of spatial attributes 130 include spacing 132, metallization ratio 134, cell width 136, number of fingers per cell 138, and whether two fingers extending from the same generatrix are adjacent to each other 140 (finger adjacency relationship 140). Spacing 132 may represent the average distance between adjacent fingers of the interdigital transducer 126. Metallization ratio 134 represents the average width of adjacent fingers divided by spacing 132. Metallization ratio 134 may be represented by the Greek letter eta (η).

[0050] The cell width 136 is related to the width of the region in the interdigital transducer 126 where the finger pattern repeats. For example, the cell width 136 may be the minimum number of fingers forming the repeating finger pattern. The cell width 136 can be measured or defined according to the target or corresponding wavelength (λ), such as a multiple of the wavelength (nλ). The number of fingers per cell 138 relates to how many fingers are present in each cell. For normal modulation, there are two fingers per wavelength, and the cell is one wavelength wide and includes two fingers. However, the specific implementation described has more fingers per cell with a larger cell width.

[0051] The finger adjacency relationship 140 corresponds to whether two fingers extending from the same busbar are adjacent in a given interdigitated transducer 126. Example implementations include an odd number of fingers per unit, thus allowing for two adjacent fingers extending from the same busbar, where the two adjacent fingers are part of different units. The following is relative to... Figure 6 , Figure 7 and Figure 9 Example description.

[0052] The dual-mode surface acoustic wave (SAW) filter 124 can be implemented as a broadband filter. For example, the bandwidth of the dual-mode SAW filter 124 can be greater than (including greater than or equal to) approximately 4% of the center frequency of its passband. In some specific implementations, this bandwidth enables the dual-mode SAW filter 124 to filter frequencies associated with multiple frequency bands. The following section discusses... Figure 2 An example of a wireless transceiver 120 is described.

[0053] Figure 2 An example wireless transceiver 120 is illustrated, including a dual-mode surface acoustic wave filter 124 that may have a modulated interdigital transducer. Generally, the wireless transceiver 120 can transmit wireless signals via at least one antenna 122. In the depicted configuration, the wireless transceiver 120 includes a transmitter 202 and a receiver 204, which are coupled to a first antenna 122-1 and a second antenna 122-2, respectively. In other embodiments, the transmitter 202 and receiver 204 may be connected to the same antenna via a duplexer (not shown). The transmitter 202 is shown as including at least one digital-to-analog converter 206 (DAC 206), at least one first mixer 208-1, at least one amplifier 210 (e.g., a power amplifier), and at least one filter 240. The filter 240 may be implemented as an acoustic filter, which may be a bandpass filter.

[0054] Receiver 204 includes at least one dual-mode surface acoustic wave filter 124, at least one amplifier 212 (e.g., a low-noise amplifier), at least one second mixer 208-2, and at least one analog-to-digital converter 214 (ADC 214). The first mixer 208-1 and the second mixer 208-2 are coupled to a local oscillator 216. Although not explicitly shown, the digital-to-analog converter 206 of transmitter 202 and the analog-to-digital converter 214 of receiver 204 may be coupled to (…). Figure 1 The application processor 108 or another processor (e.g., modem or baseband or communications processor) associated with the wireless transceiver 120.

[0055] In some implementations, the wireless transceiver 120 is implemented using multiple circuits (e.g., multiple integrated circuits), such as transceiver circuitry 236 and radio frequency front-end (RFFE) circuitry 238. Therefore, the components forming the transmitter 202 and receiver 204 are distributed across such circuits in these implementations. Figure 2 As shown, transceiver circuitry 236 includes a digital-to-analog converter 206 for transmitter 202, a mixer 208-1 for transmitter 202, a mixer 208-2 for receiver 204, and an analog-to-digital converter 214 for receiver 204. In other embodiments, digital-to-analog converter 206 or analog-to-digital converter 214 may be implemented on a separate circuit that may include application processor 108 or a modem. RF front-end circuitry 238 includes an amplifier 210 for transmitter 202, a filter 240 for transmitter 202, a dual-mode surface acoustic wave filter 124 for receiver 204, and an amplifier 212 for receiver 204.

[0056] During transmission, transmitter 202 generates an RF transmission signal 218 transmitted using antenna 122-1. To generate the RF transmission signal 218, digital-to-analog converter 206 provides a pre-up-converted transmission signal 220 to first mixer 208-1. The pre-up-converted transmission signal 220 can be a baseband signal or an intermediate frequency (IF) signal. First mixer 208-1 uses a local oscillator (LO) signal 222 provided by local oscillator 216 to up-convert the pre-up-converted transmission signal 220. First mixer 208-1 generates an up-converted signal, referred to as a pre-filtered transmission signal 224. The pre-filtered transmission signal 224 can be an RF signal and may include some noise or unwanted frequencies, such as harmonic frequencies. Amplifier 210 amplifies the pre-filtered transmission signal 224 and passes the amplified pre-filtered transmission signal 224 to filter 240.

[0057] Filter 240 filters the amplified pre-filtered transmit signal 224 to generate a filtered transmit signal 226. As part of the filtering process, filter 240 reduces noise or unwanted frequencies within the pre-filtered transmit signal 224. Transmitter 202 provides the filtered transmit signal 226 to antenna 122-1 for transmission. The emitted or transmitted filtered transmit signal 226 is represented by radio frequency transmit signal 218.

[0058] During reception, antenna 122-2 receives radio frequency (RF) received signal 228 and transmits RF received signal 228 to receiver 204. Dual-mode surface acoustic wave (SAW) filter 124 receives the received RF received signal 228, which is represented by a pre-filtered received signal 230. Dual-mode SAW filter 124 filters noise or unwanted frequencies within the pre-filtered received signal 230 to generate a filtered received signal 232. As described herein (e.g., see references...). Figure 5 , Figure 7 , Figure 11 and Figure 12 The dual-mode surface acoustic wave filter 124 (e.g., as a receiving filter for receiver 204) may include at least one DMS track. However, the receiving filter may include at least one DMS track and one or more other acoustic elements (e.g., microacoustic resonators).

[0059] Amplifier 212 of receiver 204 amplifies the filtered received signal 232 and passes the amplified filtered received signal 232 to a second mixer 208-2. The second mixer 208-2 uses a local oscillator signal 222 to down-convert the amplified filtered received signal 232 to generate a down-converted received signal 234. Analog-to-digital converter 214 converts the down-converted received signal 234 into a digital signal, which can be processed by application processor 108 or another processor associated with wireless transceiver 120 (e.g., a modem, baseband, or communications processor). Although wireless transceiver 120 is depicted as having one mixer 208 in each of transmitter 202 and receiver 204, wireless transceiver 120 can alternatively be implemented using a superheterodyne architecture.

[0060] Generally speaking, Figure 2 An example configuration of the wireless transceiver 120 is illustrated. Other configurations of the wireless transceiver 120 may support multiple frequency bands and share antenna 122 across multiple transceivers. Those skilled in the art will appreciate various other configurations that may include a dual-mode surface acoustic wave (SAW) filter 124. For example, the dual-mode SAW filter 124 may be integrated within a duplexer or common unit of the wireless transceiver 120. Furthermore, some specific implementations of the wireless transceiver 120 may use the dual-mode SAW filter 124 to implement filter 240. Additionally, the dual-mode SAW filter 124 may be external to the wireless transceiver 120. Figure 1 This is implemented in computing device 102. See next for reference. Figure 3 This describes a specific implementation example of a dual-mode surface acoustic wave filter 124.

[0061] Figure 3 An example component of a dual-mode surface acoustic wave filter 124, which may have a modulated interdigital transducer 126, is illustrated. In the depicted configuration, the example dual-mode surface acoustic wave filter 124 includes an electrode structure 302, a piezoelectric layer 304, and at least one substrate layer 306. The electrode structure 302 comprises a conductive material (such as a metal) to form electrodes and may include one or more layers. The one or more layers may include one or more metal layers and may optionally include one or more adhesive layers. As an example, the metal layers may be composed of aluminum (Al), copper (Cu), silver (Ag), gold (Au), tungsten (W), platinum (Pt), or some combination or doping form thereof. The adhesive layers may be composed of, for example, chromium (Cr), titanium (Ti), molybdenum (Mo), or some combination thereof.

[0062] Electrode structure 302 may include two or more interdigital transducers 126-1, 126-2…126-N, wherein NIn this document, it is an integer greater than one. Interdigital transducers 126-1…126-N convert electrical signals into acoustic waves and acoustic waves into filtered electrical signals. Each interdigital transducer 126 includes at least two comb structures 308-1 and 308-2. Each comb structure 308-1 and 308-2 includes a busbar 310 (e.g., a conductive segment or rail) and a plurality of fingers 312 (e.g., electrode fingers). The electrode structure 302 may optionally include two or more reflectors 314. In an example embodiment, the plurality of interdigital transducers 126-1 to 126-N are arranged between two reflectors 314, which reflect acoustic waves back to the plurality of interdigital transducers 126-1 to 126-N. About Figures 4-1 to 7 , Figure 9 , Figure 11 and Figure 12 Further examples of electrode structure 302 and interdigital transducers 126-1…126-N are described.

[0063] One or more physical characteristics of the interdigital transducers 126-1…126-N can be characterized by spatial attributes 130. Specifically, spatial attributes 130 describe the positioning, arrangement, patterning, and / or physical characteristics of the fingers 312 within the electrode structure 302. Example spatial attributes 130 include spacing 132, metallization ratio 134, cell width 136, number of fingers per cell 138, and finger adjacency 140. These spatial attributes 130 can vary on the electrode structure 302 on an individual basis or in a coordinated manner.

[0064] In some cases, transition region 128 represents one or more sets of fingers 312 located at adjacent outer edges of two adjacent interdigital transducers (e.g., IDT126-1 and 126-2). However, transition region 128 may also, or alternatively, represent one or more sets of fingers 312 present within a single interdigital transducer 126. Regarding... Figure 5 Examples of the transition region 128 are further described in the accompanying figures. These figures also depict examples of different combinations of the spatial properties 130 of different groups of fingers 312.

[0065] Generally speaking, the techniques used to implement a dual-mode surface acoustic wave (DMS) filter 124 having at least one transition region 128 with different spatial properties 130 can be applied to different types of DMS filters. For example, these techniques can be stacked with filters that do not include a compensation layer (e.g., Figure 4-1 Thin-film surface acoustic wave filter stacks) and filter stacks including compensation layers (e.g., Figure 4-2 It is used together with a high-quality temperature-compensated filter stack.

[0066] In specific embodiments, the piezoelectric layer 304 can be implemented using a variety of different materials exhibiting piezoelectric properties (e.g., the ability to convert mechanical energy into electrical energy or vice versa). Examples of materials include lithium niobate (LiNbO3), lithium tantalate (LiTaO3), quartz, aluminum nitride (AlN), scandium aluminum nitride (AlScN), or some combination thereof. Generally, the material forming the piezoelectric layer 304 can have a crystalline structure. This crystalline structure is defined by the ordered arrangement of particles (e.g., atoms, ions, or molecules). In some embodiments, the piezoelectric layer 304 has an electromechanical coupling factor (k) greater than or equal to approximately 4%. 2 ).

[0067] The substrate layer 306 includes one or more sublayers that can support passivation, temperature compensation, power handling, mode suppression, etc. As an example, the substrate layer 306 may include at least one compensation layer 326, at least one charge trapping layer 328, at least one support layer 330, or some combination thereof. These sublayers may be considered as part of the substrate layer 306 or as separate layers on their own.

[0068] The compensation layer 326 can provide temperature compensation so that the dual-mode surface acoustic wave filter 124 can achieve a target frequency temperature coefficient based on the thickness of the piezoelectric layer 304. In some embodiments, the thickness of the compensation layer 326 can be customized to provide mode suppression (e.g., suppression of stray plate modes). In example embodiments, the compensation layer 326 can be implemented using at least one silicon dioxide (SiO2) layer, at least one doped silicon dioxide layer, at least one silicon nitride layer, at least one silicon oxynitride layer, or some combination thereof. In some applications, the substrate layer 306 may not include, for example, the compensation layer 326, to reduce the cost of the dual-mode surface acoustic wave filter 124.

[0069] The charge trapping layer 328 can trap induced charges at the interface between the compensation layer 326 and the support layer 330 to, for example, suppress nonlinear substrate effects. The charge trapping layer 328 may include at least one polycrystalline silicon (poly-Si) layer (e.g., a polycrystalline silicon layer or polymorphic silicon layer), at least one amorphous silicon layer, at least one silicon nitride (SiN) layer, at least one silicon oxynitride (SiON) layer, at least one aluminum nitride (AlN) layer, diamond-like carbon (DLC), diamond, or some combination thereof.

[0070] The support layer 330 allows acoustic waves to form across the surface of the piezoelectric layer 304 and reduces the amount of energy leaking into the substrate layer 306. In some embodiments, the support layer 330 may also function as a compensation layer 326. Generally, the support layer 330 is made of a non-conductive material that provides isolation. For example, silicon (Si) (e.g., doped high-resistivity silicon), sapphire (e.g., alumina (Al₂O₃)), silicon carbide (SiC), fused silica, quartz, glass, diamond, or some combination thereof can be used to form the support layer 330. In some embodiments, the support layer 330 has a coefficient of thermal expansion (TEC) similar to that of the piezoelectric layer 304. The support layer 330 may also have a specific crystal orientation to support the suppression or attenuation of stray modes.

[0071] In some respects, the dual-mode surface acoustic wave filter 124 can be considered as a resonator or formed from multiple resonators. Sometimes, the dual-mode surface acoustic wave filter 124 can be connected to other resonators associated with the same or different layer stacks as the dual-mode surface acoustic wave filter 124. The following discusses... Figure 4-1 and Figure 4-2 Examples describing electrode structure 302, piezoelectric layer 304, and substrate layer 306.

[0072] Figure 4-1 An example implementation of a dual-mode surface acoustic wave (SAW) filter 124 using a stack of thin-film SAW filters is illustrated. Figure 4-1 The top of the image shows a three-dimensional perspective view 400-1 of the dual-mode surface acoustic wave filter 124, and... Figure 4-1 The bottom of the image shows a two-dimensional cross-sectional view 400-2 of the dual-mode surface acoustic wave filter 124.

[0073] The dual-mode surface acoustic wave filter 124 includes at least one electrode structure 302, at least one piezoelectric layer 304, and at least one substrate layer 306. In the configuration depicted in the two-dimensional cross-sectional view 400-2, the piezoelectric layer 304 is disposed between the electrode structure 302 and the substrate layer 306. Figure 4-1 A portion of the electrode structure 302 depicted includes at least a portion of an interdigital transducer 126 (IDT 126). The electrode structure 302 may include... Figure 4-1 One or more additional interdigital transducers 126 not explicitly shown. Furthermore, Figure 4-1 The interdigital transducer 126 depicted may include Figure 4-1 Additional finger-like features 312 not explicitly shown in the text.

[0074] In the three-dimensional perspective view 400-1, the interdigital transducer 126 is shown as having two comb-like structures 308-1 and 308-2, wherein fingers 312 extend from two busbars 310-1 and 310-2 toward each other. As shown, the fingers 312 are interlocked between the two busbars 310-1 and 310-2 of the interdigital transducer 126 (e.g., arranged in an interdigital manner). In other words, the fingers 312 connected to the first busbar 310-1 extend toward the second busbar 310-2, but are not connected to the second busbar 310-2. Therefore, a first barrier region 402-1 (e.g., a lateral gap region) exists between the ends of these fingers 312 on the first busbar 310-1 and the second busbar 310-2. Similarly, the fingers 312 connected to the second busbar 310-2 extend toward the first busbar 310-1, but are not connected to the first busbar 310-1. Therefore, there is a barrier region 402-2 between the ends of these fingers 312 from the second busbar 310-2 and the first busbar 310-1.

[0075] Along the directions of generatrices 310-1 and 310-2, there is an overlapping region 404, in which a portion of one finger 312 overlaps with a portion of an adjacent finger 312. Figure 4-1 In this example, two adjacent fingers extend from different busbars 310-1 and 310-2. This overlapping region 404 may be referred to as an aperture, track, or active region, in which an electric field is generated between the fingers 312 to cause acoustic waves 406 to form at least in this region of the piezoelectric layer 304.

[0076] The physical periodicity of the fingers 312 is referred to as the spacing 132 of the interdigital transducers 126. The spacing 132 can be indicated or represented in various ways. For example, in some aspects, the spacing 132 may correspond to a magnitude of the distance between adjacent fingers 312 of the interdigital transducers 126 in the overlapping region 404. For example, this distance may be defined as the distance between the center points of each finger in the fingers 312. When the fingers 312 have a uniform width, this distance can typically be measured between the right (or left) edge of one finger 312 and the right (or left) edge of the adjacent finger 312. In some aspects, the average distance between adjacent fingers 312 of the interdigital transducers 126 can be used as the spacing 132 for a given segment of the overlapping region 404 along the first generatrix 310-1 and the second generatrix 310-2. The frequency of the piezoelectric layer 304 vibration is the dominant resonant frequency of the electrode structure 302. The frequency is determined at least in part by the spacing 132 of the interdigital transducers 126 and other properties of the dual-mode surface acoustic wave filter 124.

[0077] In the three-dimensional perspective view 400-1, the dual-mode surface acoustic wave filter 124 is defined by a first (X) axis 408, a second (Y) axis 410, and a third (Z) axis 412. The first axis 408 and the second axis 410 are parallel to the flat surface of the piezoelectric layer 304, and the second axis 410 is perpendicular to the first axis 408. The third axis 412 is aligned with (e.g., substantially perpendicular or orthogonal to) the normal to the flat surface of the piezoelectric layer 304. The generatrices 310-1 and 310-2 of the interdigital transducer 126 are oriented parallel to the first axis 408. The fingers 312 of the interdigital transducer 126 are oriented parallel to the second axis 410. Furthermore, the orientation of the piezoelectric layer 304 allows acoustic waves 406 to form primarily along or parallel to the first axis 408. Therefore, acoustic waves 406 are formed in a direction substantially perpendicular or orthogonal to the fingers 312 of the interdigital transducer 126.

[0078] Figure 4-2 An example implementation of a dual-mode surface acoustic wave (SAW) filter 124 using a high-quality temperature-compensated SAW filter stack is illustrated. Figure 4-2 The top shows a three-dimensional perspective view 400-3 of the dual-mode surface acoustic wave filter 124, and... Figure 4-2 The bottom of the image shows a two-dimensional cross-sectional view 400-4 of the dual-mode surface acoustic wave filter 124.

[0079] The dual-mode surface acoustic wave filter 124 includes at least one electrode structure 302, at least one piezoelectric layer 304, and at least one compensation layer 326. The compensation layer 326 can provide temperature compensation so that the dual-mode surface acoustic wave filter 124 can achieve a target frequency temperature coefficient. In an exemplary embodiment, the compensation layer 326 may be implemented using at least one silicon dioxide layer.

[0080] In the configuration depicted in the two-dimensional cross-sectional views 400-4, electrode structure 302 is disposed between piezoelectric layer 304 and compensation layer 326. Piezoelectric layer 304 can form the substrate of dual-mode surface acoustic wave filter 124.

[0081] The electrode structure 302 of the high-quality temperature-compensated filter stack can be similar to the one described above. Figure 4-1 The electrode structure 302 described in the thin-film surface acoustic wave filter stack is similar to that described above. Similarly, the piezoelectric layer 304 of the high-quality temperature-compensated filter stack can be similar to that described above. Figure 4-1 The piezoelectric layer 304 is described in the thin-film surface acoustic wave filter stack. However, with Figure 4-1 Compared to the piezoelectric layer 304 stacked in thin-film surface acoustic wave (SAW) filters, the piezoelectric layer 304 stacked in high-quality temperature-compensated SAW filters can be thicker. Similar to... Figure 4-1 Stacked thin-film surface acoustic wave filters, Figure 4-2The high-quality temperature-compensated surface acoustic wave filter stack may also include barrier regions 402-1 and 402-2 and overlapping region 404.

[0082] Those skilled in the art will understand that various filter stacks can be implemented therein for a dual-mode surface acoustic wave filter 124. It should be understood that, although in Figure 4-1 and Figure 4-2 The illustration shows a certain number of fingers 312, but in a given physical implementation, the actual number of fingers, the length and width of the fingers 312 and busbars 310-1 and 310-2, the spacing of the fingers 312, etc., can vary. These parameters depend on the specific application and the characteristics of the target filter. Furthermore, the dual-mode surface acoustic wave filter 124 may include multiple interdigital transducers 126 to achieve a given filter transfer function. See below for further details. Figure 5 An example electrode structure 302 with multiple interdigital transducers 126 is described.

[0083] Figure 5 An example electrode structure 302 is illustrated, which may include a dual-mode surface acoustic wave (DMS) filter 124 comprising modulated interdigital transducers 126. In the depicted configuration, electrode structure 302 includes a plurality of interdigital transducers 126-1 to 126-N to provide DMS tracks, wherein N It usually represents a positive integer. In the specific implementation of the example, the variable N The values ​​can be 3, 4, 5, 7, etc. Therefore, a DMS track can include any number of interdigital transducers. See also... Figure 2 The receive filter (e.g., DMS filter 124) or transmit filter 240 may include at least one DMS track.

[0084] Electrode structure 302 also includes a first reflector 314-1 and a second reflector 314-2. Interdigital transducers 126-1 to 126-N are arranged between the first reflector 314-1 and the second reflector 314-2. Interdigital transducers 126-1 to 126-N can be arranged, for example, spatially or physically sequentially or in series together between the first reflector 314-1 and the second reflector 314-2. With this positioning, reflectors 314-1 and 314-2 reflect sound waves 406 back to interdigital transducers 126-1 to 126-N. Each reflector 314-1 and 314-2 within electrode structure 302 can have a grid structure of two busbars 310 and conductive finger-like strips connected to these two busbars 310. In some specific implementations, the spacing of reflectors 314 can be similar to the spacing 132 of interdigital transducers 126 to reflect sound waves 406 within the resonant frequency range.

[0085] As shown in the figure, each interdigital transducer 126 includes a first busbar 310-1, a second busbar 310-2, and a plurality of fingers 312-1 to 312-B, wherein... B Represents a positive integer. The first busbar 310-1 and the fingers 312-1 to 312-A form at least a portion of the first comb-like structure 308-1, wherein A Indicates less than B A positive integer. Fingers 312-1 to 312-A are connected to the first busbar 310-1 and extend along the second (Y) axis 410 toward the second busbar 310-2 without connecting to it. The second busbar 310-2, along with fingers 312-(A+1) and 312-B, forms at least a portion of the second comb structure 308-2. Fingers 312-(A+1) and 312-B are connected to the second busbar 310-2 and extend along the second (Y) axis 410 toward the first busbar 310-1 without connecting to it.

[0086] The fingers 312 within the interdigital transducer 126 can be associated with, for example, a first transition region 128-1, a central region 502, or a second transition region 128-2. In the depicted example, the central region 502 is positioned along a first axis 408 between the first transition region 128-1 and the second transition region 128-2. The first transition region 128-1 and the second transition region 128-2 are associated with opposite outer edges of the interdigital transducer 126. For example, the first transition region 128-1 is associated with the “left” edge of the interdigital transducer 126 (e.g., the left edge of the left edge of the right edge of the left edge of the right edge of the right edge of the left edge of the right edge of the interdigital transducer 126). Figure 5 The first transition region 128-1 and the second transition region 128-2 are associated with the "right" edge of the interdigital transducer 126, as depicted in the diagram. Although not explicitly shown, the first transition region 128-1 and the second transition region 128-2 may also include the fingers 312 of adjacent interdigital transducers 126. The central region 502 is associated with the center of the interdigital transducer 126 and does not include any additional fingers 312 associated with adjacent interdigital transducers 126. In other embodiments, the first transition region 128-1 and the second transition region 128-2 may also include the fingers 312 of adjacent interdigital transducers 126. Figure 5 Compared to the area shown, the interdigital transducer 126 may include more, fewer, and / or different areas. For example, the interdigital transducer 126 may include a transition region 128 that is not located at or otherwise associated with the edge of the interdigital transducer 126.

[0087] Transition region 128 can facilitate smoother, less abrupt changes in the trajectory of sound waves relative to multiple sets of fingers with different spatial properties 130. At least one transition region 128 may include portions of two adjacent interdigital transducers 126 forming a smooth, continuous transition, and may further include quasi-periodic grids between adjacent elements. Additionally or alternatively, at least one transition region 128 may include finger portions within a single interdigital transducer 126 forming a smooth, continuous transition for the traveling sound waves. Generally, region 128 may include spatial properties 130 that differ from the spatial properties of one or more other regions 128. For example, the spacing 132 of one or more interdigital transducers 126, the metallization ratio 134, the unit width 136, the number of fingers per unit 138, or the finger adjacency 140 may vary on the first axis 408, as referred to below. Figure 6 Further description.

[0088] Figure 6 An example of a modulated interdigital transducer 126 is illustrated, comprising multiple regions having multiple sets of fingers, the multiple regions including regions having adjacent fingers along the same generatrix. For clarity, from Figure 6 , Figure 7 and Figure 9 The shaded area indicating the piezoelectric layer 304 is omitted. As illustrated, the interdigital transducer 126 includes at least two regions: a first region 128-1 and a second region 128-2. The interdigital transducer 126 also includes at least two buses: a first bus 310-1 and a second bus 310-2. These regions may differ from each other in one or more aspects of spatial property 130 (SP 130). Example aspects of spatial property 130 include pitch 132, metallization ratio 134, cell width 136, and finger positioning.

[0089] Finger positioning can include, for example, fingers extending from the same generatrix and adjacent to each other (finger adjacency 140) and fingers extending from the same generatrix and spaced apart by more than one intermediate finger, even if they are positioned continuously along the same generatrix (e.g., gaps exist between continuous fingers). As used herein, adjacent fingers are fingers that do not have intermediate fingers from either generatrix (e.g., including those from opposing generatrixes) and are (e.g., extend from the same generatrix). An example of adjacent fingers is shown at 606. Continuous fingers are fingers that do not have intermediate fingers from the same generatrix and are (e.g., extend from the same generatrix). Thus, two continuous fingers can define a gap in which at least one finger from an opposing generatrix is ​​positioned. An example of continuous fingers is shown at 608. Thus, adjacent fingers are also continuous fingers, but continuous fingers are not necessarily adjacent. In the context of a given cell width 136, finger positioning can also include a number of fingers per cell 138.

[0090] In the specific implementation of the example, (for example, Figures 1 to 5 The dual-mode surface acoustic wave filter 124 includes at least one interdigital transducer 126. The interdigital transducer 126 includes a first bus 310-1, a second bus 310-2, and a plurality of fingers 312 extending from the first bus 310-1 toward the second bus 310-2. Figure 6 For example, these multiple fingers 312 may include those fingers 312 with a cross-shading fill pattern. Two examples of such fingers are shown in... Figure 6 The text clearly indicates that they are finger-shaped objects 312-1 and 312-3.

[0091] Among the plurality of fingers 312 with a cross-shading pattern, there exists a first group of fingers 604-1 having a first spatial attribute 130-1. The first group of fingers 604-1 includes fingers 312-3. The plurality of fingers 312 also includes a second group of fingers 604-2 having a second spatial attribute 130-2 different from the first spatial attribute 130-1. The second group of fingers 604-2 includes fingers 312-1. Figure 6 In the second spatial attribute 130-2, at least two fingers in the second set of fingers 604-2 are positioned adjacent to each other, an example of which is indicated at 606.

[0092] The second set of fingers 604-2 may be positioned adjacent to the first set of fingers 604-1 along the first busbar 310-1 of at least one interdigital transducer 126. Alternatively, another region of another set of fingers with different modulations (e.g., Figure 5 The central region 502 can be located between the first region 128-1, which includes the first set of fingers 604-1, and the second region 128-2, which includes the second set of fingers 604-2.

[0093] In some specific implementations, the first spatial attribute 130-1 of the first group of fingers 604-1 includes the absence of adjacent fingers or their association within the first group of fingers 604-1. In other words, for fingers extending from the first busbar 310-1 and possessing the first spatial attribute 130-1, consecutive fingers are not adjacent because there exists a finger extending from the second busbar 310-2 positioned or located between two consecutive fingers of the first busbar 310-1.

[0094] In some implementations, the second set of fingers 604-2 is positioned at or otherwise associated with the outer edge of at least one interdigital transducer 126. Therefore, the second set of fingers 604-2 may be part of the transition region of another interdigital transducer 126 relative to a given dual-mode surface acoustic wave filter 124. This is referenced below. Figure 7 Further description.

[0095] In some cases, the first spatial attribute 130-1 may include a first spacing of the first set of fingers 604-1. The second spatial attribute 130-2 may include a second spacing of the second set of fingers 604-2, wherein the second spacing differs from the first spacing. For example, the second spacing may be smaller than the first spacing, and vice versa. Figure 6 As depicted, the second spacing of the fingers in the second region 128-2 is smaller than the first spacing of the fingers in the first region 128-1. Additionally or alternatively, the first spatial attribute 130-1 may include a first metallization ratio of the first set of fingers 604-1. The second spatial attribute 130-2 may include a second metallization ratio of the second set of fingers 604-2, wherein the second metallization ratio differs from the first metallization ratio.

[0096] In an exemplary implementation, at least one interdigital transducer 126 may further include a plurality of other fingers 312 extending from the second busbar 310-2 toward the first busbar 310-1. Figure 6 For example, these additional fingers 312 may include those fingers 312 with a dense dot-filled pattern. Two examples of such fingers are shown in... Figure 6 The fingers are explicitly designated as 312-2 and 312-4. Based on the first set of fingers 604-1 and the third set of fingers 604-3, the first region 128-1 may include a plurality of fingers 312 arranged such that the fingers from the different buses 310-1 and 310-2 of the interdigital transducer 126 alternate.

[0097] Among the plurality of other fingers 312 with a dense dot-filled pattern, there is a third group of fingers 604-3 having a first spatial attribute 130-1. The third group of fingers 604-3 includes fingers 312-4. The plurality of other fingers 312 also includes a fourth group of fingers 604-4 having a third spatial attribute 130-3. The fourth group of fingers 604-4 includes fingers 312-2. The third spatial attribute 130-3 includes at least two fingers in the fourth group of fingers 604-4 being separated by a gap 608. The gap 608 has a width sufficient to allow at least two fingers in the second group of fingers 604-2 that are positioned adjacent to each other (as indicated at 606) to be positioned in the fourth group of fingers 604-4, defining the width between at least two fingers defining the gap 608. At least two fingers in the defining gap 608 of the fourth group of fingers 604-4 are not adjacent to each other, but are continuous along the second generatrix 310-2.

[0098] As exemplified, Figure 6Each region 128 has different units 610. The first region 128-1 has first units 610-1. The first unit 610-1 may include, for example, two fingers per unit and a unit width of one wavelength (λ). The second region 128-2 has second units 610-2. The second unit 610-2 may include, for example, five fingers per unit and a unit width of two wavelengths (2λ). This document specifically refers to... Figure 7 and Figure 9 Other examples are described.

[0099] However, generally speaking, the combination of the second group of fingers 604-2 and the fourth group of fingers 604-4 has an odd number of fingers in each of the multiple units 610-2 of the interdigital transducer 126. The width of each unit 610-2 in the multiple units is based on the target wavelength (λ). For example, the width of each unit 610-2 in the multiple units may be based on a multiple (n) or (nλ) of the target wavelength (λ). The illustrated interdigital transducer 126 includes at least one unit 610-2 in the multiple units, which has an odd number of fingers 138 per unit (e.g., Figure 1 and Figure 3 Here, at least one unit 610-2 includes a finger 312 having a second spatial property 130-2 and a third spatial property 130-3.

[0100] To facilitate transition to another region 128 (e.g., first region 128-1), the interdigital transducer 126 may also include at least one partial unit 610-2 (not shown) having fewer fingers than the odd number of fingers 138 per unit. The partial unit may include two or more fingers corresponding to a second spatial attribute 130-2 or a third spatial attribute 130-3. For example, the second region 128-2 may have a partial unit 610-2 comprising three or four fingers, while the “complete” unit 610-2 comprises five fingers. The partial unit 610-2 may be positioned between the complete unit 610-2 with five fingers and the unit 610-1 of the first region 128-1 with two fingers. Reference is made below in particular to… Figure 11 and Figure 12 Further description of examples of some units.

[0101] Figure 7 An example is illustrated of two modulated interdigital transducers 126-1 and 126-2 comprising multiple regions 128 having multiple sets of fingers, wherein each interdigital transducer includes at least one region having adjacent fingers. The first interdigital transducer 126-1 corresponds to Figure 6 The interdigital transducer 126 is depicted in the image. Figure 7The portion of the dual-mode surface acoustic wave filter 124 depicted also includes a portion of the second interdigital transducer 126-2 and a grating separator 702 disposed between the two interdigital transducers 126.

[0102] In an example, the grid bar separator 702 includes at least two metal bars coupled together at opposite ends and extending across the “height” of the dual-mode surface acoustic wave filter 124. The two metal bars are substantially parallel to the plurality of fingers 312 of the first interdigital transducer 126-1 or the second interdigital transducer 126-2, including, depending on whether the word “or” is interpreted as a separator, or substantially parallel to both. As shown, the grid bar separator 702 can be positioned between the first interdigital transducer 126-1 and the second interdigital transducer 126-2. Although not shown, another grid bar separator 702 can be positioned between the second interdigital transducer 126-2 and the third interdigital transducer 126-3 (e.g., if “N>=3”). Figure 3 The interdigital transducers are positioned between each other. Additionally, the grid separator 702 may alternatively include a metal strip (e.g., a single metal strip) extending across the “height” of the dual-mode surface acoustic wave filter 124 (e.g., spanning approximately the space between the two busbars, potentially also including the busbars). In other words, a metal strip can serve as a shielding structure between adjacent interdigital transducers for phase correction.

[0103] In an example implementation, the second interdigital transducer 126-2 may include a third busbar 310-3, a fourth busbar 310-4, and a plurality of other fingers 312. The plurality of other fingers 312 (with a cross-shading pattern) extend from the third busbar 310-3 toward the fourth busbar 310-4. The plurality of other fingers 312 includes a third set of fingers 604-3 having a third spatial attribute 130-3. The plurality of other fingers 312 also includes a fourth set of fingers 604-4 having a fourth spatial attribute 130-4 different from the third spatial attribute 130-3. As shown, the fourth spatial attribute 130-4 includes at least two fingers of the fourth set of fingers 604-4 positioned adjacent to each other, as indicated at 706.

[0104] The fourth set of fingers 604-4 of the second interdigital transducer 126-2 is physically closer to the second set of fingers 604-2 of the first interdigital transducer 126-1 than to the third set of fingers 604-3 of the second interdigital transducer 126-2. This can occur, for example, by positioning the fourth set of fingers 604-4 between the second set of fingers 604-2 and the third set of fingers 604-3, as... Figure 7 As shown.

[0105] As illustrated, the second interdigital transducer 126-2 includes two regions: a third region 128-3 and a fourth region 128-4. The third region 128-3 may include multiple units, such as the third unit 610-3. The third spatial attribute 130-3 of the third set of fingers 604-3 includes the absence of adjacent fingers in the third set of fingers 604-3 and the spacing of the third set of fingers 604-3. In an example, the third spatial attribute 130-3 of the third set of fingers 604-3 may be substantially equivalent to the first spatial attribute 130-1 of the first set of fingers 604-1. Therefore, the third unit 610-3 may be substantially equivalent to the first unit 610-1 in terms of spatial attribute 130. For example, each of the first spatial attribute 130-1 and the third spatial attribute 130-3 may have the same spacing 132, metallization ratio 134, unit width 136, or number of fingers per unit 138, except that there are no adjacent fingers.

[0106] Conversely, the fourth spatial property 130-4 of the fourth group of fingers 604-4 is exemplified as different from the second spatial property 130-2 of the second group of fingers 604-2. For example, the second group of fingers 604-2 includes a first number of fingers in each of the multiple units of the second region 128-2 of the first interdigital transducer 126-1 (e.g., Figure 1 and Figure 3 (of 138). Figure 7 In the example, there are five fingers (138) per unit, as shown in unit 610-2 of the second region 128-2. The fourth group of fingers 604-4 includes a second number of fingers (138) per unit in the multiple units of the fourth region 128-4 of the second interdigital transducer 126-2. Figure 7 In the example, there are instances of seven fingers (138) per cell, as shown in cell 610-4 of the fourth region 128-4. Therefore, in the illustrated example, the first number of fingers per cell differs from (and in this case is less than) the second number of fingers per cell. Other differences between the second spatial attribute 130-2 and the fourth spatial attribute 130-4 may include spacing 132, metallization ratio 134, or cell width 136.

[0107] Figure 8 Example graphs 800 depicting two example transfer functions are shown. Transfer function 801, depicted by a dashed line, represents a two-mode surface acoustic wave filter that does not employ the techniques described herein. On the other hand, transfer function 802, depicted by a solid line, represents a two-mode surface acoustic wave filter 124 that does implement aspects of the techniques described herein, such as through a modulated interdigital transducer 126.

[0108] Left skirt region 804 illustrates how the modulated interdigital transducer 126 can steepen the left skirt. The left skirt of transfer function 802 is steeper than the left skirt of transfer function 801. This steepening of the left skirt can facilitate operation of the wireless transceiver 120 in two close frequency bands, such as receive band 8 (Rx band 8) and transmit band 8 (Tx band 8)). By employing the techniques described herein, the left skirt can be made steeper, which allows the use of piezoelectric materials with positive reflection signs as electrodes, such as lithium niobate (LiNbO3) 122 (LN122), when adjacent lower frequency bands are close to a given frequency band.

[0109] Figure 9 Three example cell arrangements of interdigital transducers for modulating dual-mode surface acoustic wave (SAW) filters are illustrated. As described herein, the modulated interdigital transducers allow the stopband of the transducers to be shifted from the frequency with maximum excitation. In some specific implementations, the interdigital transducers are modulated using cells of width nλ and 2n+1 fingers in each cell, where λ corresponds to the wavelength targeted by the filter, and n This indicates a multiple (e.g., n>=1 or n>=2). Within each cell, fingers can connect to alternating busbars. On the other hand, at cell boundaries, fingers on the same busbar can be adjacent to each other.

[0110] In this type of cell, the finger period is nλ / (2n+1), therefore, compared to a "normal" finger cell with a finger period of λ / 2, the corresponding stopband is shifted towards higher frequencies. n Compared to the value, the relatively smaller one in this formula n This value results in a relatively small finger cycle. Manufacturing constraints regarding the minimum structure width may influence design considerations. A relatively large... n This value reduces the frequency shift between the maximum excitation below the stopband and the stopband boundary. Therefore, n A reasonable upper limit can be derived from the stopband width. For example, the higher the reflectivity of each band, and therefore the wider the stopband, the greater the maximum effective reflectivity. n The lower the value, the better.

[0111] Each interdigital transducer in the depicted interdigital transducer has an example width of 12λ, which extends along the travel path of the acoustic wave along the dual-mode surface acoustic wave filter. The linear arrangement of such units produces a finger spatial property 130, where, after each unit width nλ, two adjacent fingers from two different units are connected at the same busbar. Figure 9An example of such a repeating cellular arrangement is depicted. For a specific example, n=2 at 902-2, n=3 at 902-3, and n=4 at 902-4. In the example modulation at 902-2, the cell width is 2λ, and the cell contains five fingers (2×2+1). In each cell, two fingers emerge from the "top" (e.g., ...). Figure 9 The generatrix (as depicted in the image) extends, and three fingers emerge from the "below" (as shown in the image). Figure 9 (The busbar extension is depicted in the image.)

[0112] At example modulation 902-3, the cell width is 3λ, and the cell contains seven fingers (2×3+1). For each cell, three fingers extend from the "upper" bus and four fingers extend from the "lower" bus. At example modulation 902-4, the cell width is 4λ, and the cell contains nine fingers (2×4+1). In each cell, four fingers extend downward from the "upper" bus and five fingers extend upward from the "lower" bus. In each of these example modulations 902, two fingers are adjacent and extend from the same ("lower") bus. Here, fingers from the same bus are adjacent at the boundary between cells. Another ("upper") bus accommodates adjacent fingers by including a gap between two consecutive but non-adjacent fingers extending from the upper bus.

[0113] As used herein, adjacent fingers are fingers that do not have intermediate fingers originating from any busbar, and consecutive fingers are fingers that do not have intermediate fingers originating from the same busbar. Therefore, adjacent fingers are also consecutive fingers, but consecutive fingers are not necessarily adjacent. Adjacent fingers and consecutive fingers can belong to different units of the interdigitated transducer 126. Although references... Figure 9 Several example modulations are described, but different modulations can be used depending on the cellular scheme or otherwise. n The value is used to modulate the interdigital transducer 126.

[0114] Figure 10 Examples Figure 9 Example curves for two aspects of three example modulations 902-2, 902-3, and 902-4 of an interdigital transducer with three example unit arrangements are shown in Figure 1000. These two aspects are represented by solid lines for the real part of the admittance and dashed lines for reflections at the acoustic port. The thickest or deepest line corresponds to modulation 902-2 with five fingers over two wavelengths. The thinnest or shallowest line corresponds to modulation 902-4 with nine fingers over four wavelengths. The medium-thickness line corresponds to modulation 902-3 with seven fingers over three wavelengths. As shown in Figure 1000, with… n As the value increases, the acoustic port reflection shifts to the left towards lower frequencies. Furthermore, directly below the passband, the admittance typically increases with...n The value increases as it increases.

[0115] Figure 11 An example dual-mode surface acoustic wave filter 124 including three example modulated interdigital transducers is illustrated. As shown in the figure, the dual-mode surface acoustic wave filter 124 is arranged from left to right (e.g., Figure 11 The image depicted includes a first reflector 314-1, a first interdigital transducer 126-1 (IDT 126-1), a first grid separator 702-1 (GD 702-1), a second interdigital transducer 126-2 (IDT 126-2), a second grid separator 702-2 (GD 702-2), a third interdigital transducer 126-3 (IDT 126-3), and a second reflector 314-2. In an exemplary embodiment, the first interdigital transducer 126-1 includes a first region 128-1 and a second region 128-2, which also... Figure 6 and Figure 7 Depicted in the image. The second interdigital transducer 126-2 includes a fourth region 128-4 and a third region 128-3, which are located in... Figure 7 Described in the text.

[0116] In some cases, the dual-mode surface acoustic wave filter 124 can be symmetrical. In this case, the second interdigital transducer 126-2 may include another fourth region 128-4, which is substantially similar to the fourth region 128-4 adjacent to the first interdigital transducer 126-1. Further, the third interdigital transducer 126 may include another second region 128-2 and another first region 128-1. (Refer to the following...) Figure 12 These example interdigital transducers 126 and regions are described.

[0117] Figure 12 Examples Figure 11 An enlarged view of portion 1200 of an example dual-mode surface acoustic wave filter 124, wherein each of the two interdigital transducers has been divided into two sub-interdigital transducers. As illustrated, the first interdigital transducer 126-1 includes a first sub-interdigital transducer 126-11 (sub-IDT 126-11) and a second sub-interdigital transducer 126-12 (sub-IDT 126-12). The second interdigital transducer 126-2 includes a first sub-interdigital transducer 126-21 (sub-IDT 126-21) and a second sub-interdigital transducer 126-22 (sub-IDT 126-22).

[0118] In terms of examples, Figure 11 The geometry of an example symmetric three-IDT DMS orbital is shown in the figure. Figure 12The image shows a portion of the same finger-like structure in magnified form to more clearly illustrate the different parts of the interdigital transducer. The first reflector 314-1 comprises 18 metal strips, six of which are located in… Figure 12 The diagram clearly describes the first sub-interdigital transducer 126-11, which includes 12 normally modulated finger units, each comprising two fingers distributed over one wavelength. Therefore, the first sub-interdigital transducer 126-1 has 24 fingers. Thus, the width of each normally modulated finger unit is approximately one wavelength.

[0119] The second sub-interdigital transducer 126-12 is positioned between the first sub-interdigital transducer 126-11 and the first grid bar separator 702-1. The second sub-interdigital transducer 126-12 is a different modulation portion of the first interdigital transducer 126-1, and includes an odd number of fingers per unit. Each unit of the second sub-interdigital transducer 126-12 has five fingers in two wavelengths (e.g., similar to...). Figure 9 (Modulation 902-2). These three units of this type form the second sub-interdigital transducer 126-12. However, the four fingers of the "left" unit are omitted in this second sub-interdigital transducer 126-12, and this omission forms a partial unit between the two sub-interdigital transducers of the first interdigital transducer 126-1. This partial unit better adapts to the phase of the excitation wave in the first sub-interdigital transducer 126-11 and the second sub-interdigital transducer 126-12 by providing a smooth transition in terms of spacing and metallization ratio (eta). Therefore, in this example, the second sub-interdigital transducer 126-12 includes 11 fingers instead of 15.

[0120] To connect the first subinterdigital transducer 126-11 to the second subinterdigital transducer 126-12, each subinterdigital transducer can be coupled to a common "top" (e.g., ...). Figure 12 The busbar and the common "lower" busbar depicted in the image, the common busbar in Figure 11 As shown in [the image / document]. Figure 12 In the magnified portion 1200, it is clearly visible that the spacing of the second sub-interdigital transducers 126-12 is smaller than that of the first sub-interdigital transducers 126-11.

[0121] To achieve phase adaptation between the first interdigital transducer 126-1 and the second interdigital transducer 126-2 through a reduced spacing variation, two single-finger conductive (e.g., metal) strips are disposed between the two interdigital transducers 126. These are collectively referred to as the first grid bar separator 702-1. Each grid bar separator 702 may be grounded or may be floating (e.g., via a grounded grid bar or a floating grid bar). Each grid bar separator 702 may include more or fewer than two conductive strips, may be omitted from the dual-mode surface acoustic wave filter 124, or may have a different number of fingers than the other grid bar separators.

[0122] The geometry of the second interdigital transducer 126-2 is symmetrical. On the "left side," the first sub-interdigital transducer 126-21 of the second interdigital transducer 126-2 is a modulation section with a unit having three wavelength widths and seven fingers per unit (e.g., as shown in the image). Figure 9 (Modulation 902-3). Two of these units form the first sub-interdigital transducer 126-21, with a total of 14 fingers. On the "right" side of the second interdigital transducer 126-2, the second sub-interdigital transducer 126-22 includes 39 normally modulated fingers with a unit width of one wavelength, and each unit has two fingers. Figure 12 Only a portion of these 39 finger-like structures is shown. However, Figure 11 The diagram depicts these 39 fingers and another fourth region 128-4 adjacent to the second grid bar separator 702-2, which includes an additional 14 fingers across three wavelengths and ( Figure 9 Each unit contains seven finger-shaped modulators 902-3.

[0123] According to Figure 12 The example is obvious: the spacing of the first sub-interdigital transducers 126-21 of the second interdigital transducer 126-2 is greater than the spacing of the second sub-interdigital transducers 126-12 of the first interdigital transducer 126-1, and smaller than the spacing of the second sub-interdigital transducers 126-22 of the second interdigital transducer 126-2. Furthermore, the spacing of the first sub-interdigital transducers 126-11 of the first interdigital transducer 126-1 can be substantially equal to the spacing of the second sub-interdigital transducers 126-22 of the second interdigital transducer 126-2 (e.g., within the expected manufacturing variation, such as within 10%, 5%, or even 1%). It should be understood that, with Figure 11 and Figure 12 Compared to the example shown, the dual-mode surface acoustic wave filter 124 can have different numbers of interdigital transducers 126, different numbers of fingers, different combinations of unit modulation, different spacing, etc.

[0124] Figure 13 Examples Figure 11Example graph 1300 illustrates two aspects of the example dual-mode surface acoustic wave filter 124. Graph 1300 depicts the relationship between the spacing (on the left vertical axis or y-axis) and the number of fingers counted along the width of the example dual-mode surface acoustic wave filter 124 (on the horizontal axis or x-axis). The spacing is shown as a solid line. Graph 1300 also depicts the relationship between the metallization ratio (eta) (on the right vertical axis or y-axis) and the number of fingers counted along the width of the example dual-mode surface acoustic wave filter 124. The metallization ratio (eta) is shown as a dashed line. The number of fingers depicted ranges from 1 to 176.

[0125] As is evident from graph 1300, the spacing on the second sub-interdigital transducer 126-12 of the first interdigital transducer 126-1 and the spacing on the first sub-interdigital transducer 126-21 of the second interdigital transducer 126-2 are smaller than the spacing in the normal modulation section. Since the second sub-interdigital transducer 126-12 has five fingers within two wavelengths, while the first sub-interdigital transducer 126-21 has seven fingers within three wavelengths, the average spacing of the second sub-interdigital transducer 126-12 is smaller than the average spacing of the first sub-interdigital transducer 126-21.

[0126] Figure 14 Examples Figure 11 and Figure 12 Example curves of two aspects of the example first modulated interdigital transducer 126-1 depicted in Figure 1400. Figure 15 Examples Figure 11 and Figure 12 Example graphs 1400 and 1500 depict the same two aspects of the example second modulated interdigital transducer 126-2. These graphs 1400 and 1500 depict the relationship between reflection (on the left vertical axis or y-axis) and frequency (on the horizontal axis or x-axis). Reflection is shown with solid lines. These graphs 1400 and 1500 also depict the relationship between electroacoustic conversion (on the right vertical axis or y-axis) and frequency. Electroacoustic conversion is shown with dashed lines. The frequency range depicted is from 700 MHz to 1300 MHz.

[0127] Therefore, the reflection at the right acoustic port of the reflector and the two sub-sections of the corresponding interdigital transducer 126 are depicted with solid lines. The voltage conversion from the common electrical port of the two sub-sections of the corresponding interdigital transducer 126 to the right acoustic port is shown with dashed lines. Figure 14 Corresponding to the first reflector 314-1 (“REF”), the first sub-interdigital transducer 126-11 (“IDT 11”) of the first interdigital transducer 126-1, and the second sub-interdigital transducer 126-12 (“IDT 12”) of the first interdigital transducer 126-1. Figure 15The first sub-interdigital transducer 126-21 (“IDT 21”) corresponds to the second interdigital transducer 126-2 and the second sub-interdigital transducer 126-22 (“IDT 22”).

[0128] exist Figure 14 and Figure 15 The image shows a contrast between the shifted stopband of the abnormal modulation portion of the interdigital transducer 126 (e.g., the second sub-interdigital transducer 126-12 and the first sub-interdigital transducer 126-21) and the normal modulation portion (e.g., the first sub-interdigital transducer 126-11 and the second sub-interdigital transducer 126-22). The vertical lines at 925 MHz and 960 MHz show the passband of the receiving band 8 (Rx band 8). The stopbands of the two abnormal modulation sub-interdigital transducers 126 (e.g., sub-IDT-12 and sub-IDT-21) are clearly shifted above 925 MHz, but the electroacoustic conversion is close to a local maximum at this frequency.

[0129] Figure 16 This is a flowchart illustrating an example process 1600 for manufacturing a two-mode surface acoustic wave filter with a modulated interdigital transducer. Process 1600 is described as a set of blocks 1602 and 1604 specifying operations that can be performed. However, the operations are not necessarily limited to... Figure 16 The order shown or described herein is not applicable, as these operations can be implemented in an alternative order or in a manner that is wholly or partially overlapping. Furthermore, more, fewer, and / or different operations can be implemented to perform process 1600 or alternative processes. Operations represented by the illustrated boxes of process 1600 can be performed to manufacture (e.g., Figures 1 to 5 , Figure 7 or Figure 11 (of) a dual-mode surface acoustic wave filter 124. More specifically, the operation of process 1600 can be performed at least in part to manufacture (e.g., Figure 1 , Figures 3 to 7 , Figure 9 , Figure 11 or Figure 12 (of) one or more interdigital transducers 126.

[0130] At block 802, a first set of fingers is provided for at least one interdigital transducer of a dual-mode surface acoustic wave filter, wherein the first set of fingers extends from a first busbar of the at least one interdigital transducer toward a second busbar of the at least one interdigital transducer, and wherein the first set of fingers has a first spatial property. For example, a first set of fingers 604-1 may be provided for at least one interdigital transducer 126 of a dual-mode surface acoustic wave filter 124. The first set of fingers 604-1 may extend from the first busbar 310-1 of the at least one interdigital transducer 126 toward the second busbar 310-1 of the at least one interdigital transducer 126, and the first set of fingers 604-1 may have a first spatial property 130-1.

[0131] For example, the first set of fingers 604-1 can be positioned with reflector 314 and can have a first spacing 132. Furthermore, for the first spatial attribute 130-1, the first set of fingers 604-1 can have an even number of fingers 312 per unit 610-1, such as two fingers per wavelength unit or four fingers per wavelength unit, or the first set of fingers 604-1 may not have adjacent fingers.

[0132] At block 804, a second set of fingers is provided for the at least one interdigital transducer of the dual-mode surface acoustic wave filter, wherein the second set of fingers extends from the first busbar toward the second busbar, wherein the second set of fingers has a second spatial property different from the first spatial property, and wherein the second spatial property includes at least two fingers in the second set of fingers being positioned adjacent to each other. For example, a second set of fingers 604-2 may be provided for at least one interdigital transducer 126 of the dual-mode surface acoustic wave filter 124. The second set of fingers 604-2 may extend from the first busbar 310-1 toward the second busbar 310-2, and the second set of fingers 604-2 may have a second spatial property 130-2 different from the first spatial property 130-1. Here, the second spatial property 130-2 may include positioning at least two fingers 312 in the second set of fingers 604-2 adjacent to each other.

[0133] For example, a second set of fingers 604-2 may be disposed between the first set of fingers 604-1 and another interdigital transducer 126, and may have a second spacing 132 different from the first spacing 132 of the first set of fingers 604-1. The corresponding spacing 132 may be part of the corresponding spatial property 130. In some cases, for the second spatial property 130-2, the second set of fingers 604-2 may have an odd number of fingers 312 per unit 610-2, such as five fingers per two wavelength units or seven fingers per three wavelength units, or the second set of fingers 604-2 may have adjacent fingers as indicated at 606.

[0134] The following paragraphs describe some aspects of example implementations and / or example configurations related to the apparatus and / or process presented above.

[0135] Example aspect 1: An apparatus comprising: A dual-mode surface acoustic wave filter, comprising: At least one interdigital transducer, the at least one interdigital transducer including a first busbar, a second busbar, and a plurality of fingers extending from the first busbar toward the second busbar, the plurality of fingers including: The first group of finger-like objects possessing the first spatial property; and A second set of fingers having a second spatial attribute different from the first spatial attribute, wherein the second spatial attribute includes at least two fingers in the second set of fingers being positioned adjacent to each other.

[0136] Example aspect 2: The apparatus according to example aspect 1, wherein: The first spatial attribute includes the first spacing between the first set of fingers; and The second spatial attribute includes a second spacing between the second set of fingers, which is different from the first spacing.

[0137] Example aspect 3: The apparatus according to example aspect 1 or 2, wherein: The first spatial attribute includes the first metallization ratio of the first set of fingers; and The second spatial attribute includes a second metallization ratio of the second set of fingers, which is different from the first metallization ratio.

[0138] Example aspect 4: The apparatus according to any one of the foregoing example aspects, wherein the first spatial attribute of the first set of fingers includes the absence of adjacent fingers in the first set of fingers.

[0139] Example aspect 5: The apparatus according to any one of the foregoing example aspects, wherein the second set of fingers is positioned adjacent to the first set of fingers along the first busbar of the at least one interdigital transducer.

[0140] Example aspect 6: The apparatus according to any one of the foregoing example aspects, wherein the second set of fingers is associated with the outer edge of the at least one interdigital transducer.

[0141] Example aspect 7: The apparatus according to any one of the foregoing example aspects, wherein: The at least one interdigital transducer includes a plurality of other fingers extending from the second busbar toward the first busbar, the plurality of other fingers including: A third set of finger-like objects possessing the first spatial attribute; and A fourth set of fingers having a third spatial property, the third spatial property including at least two fingers in the fourth set of fingers being separated by a gap sufficient to allow at least two fingers in the second set of fingers that are positioned adjacent to each other to be positioned between at least two fingers in the fourth set of fingers.

[0142] Example aspect 8: The apparatus according to example aspect 7, wherein at least two of the fourth set of fingers are not adjacent to each other, but are continuous along the second generatrix.

[0143] Example aspect 9: The apparatus according to example aspect 7, wherein: The combination of the second group of fingers and the fourth group of fingers has an odd number of fingers in each of the plurality of units of the at least one interdigital transducer; and The width of each of the plurality of cells is based on the target wavelength.

[0144] Example aspect 10: The apparatus according to example aspect 9, wherein the at least one interdigital transducer comprises: At least one of the plurality of units having an odd number of fingers in each unit, the at least one unit comprising fingers having the second spatial attribute and the third spatial attribute; and At least one partial unit of the plurality of units has fewer fingers than the odd number of fingers in each unit, the at least one partial unit comprising two or more fingers corresponding to at least one of the second spatial attribute or the third spatial attribute.

[0145] Example aspect 11: The apparatus according to example aspect 9, wherein the width of each of the plurality of cells is based on a multiple of the target wavelength.

[0146] Example aspect 12: The apparatus according to example aspect 11, wherein: Each unit contains an odd number of fingers, including five fingers; and The multiple of the target wavelength includes multiples of two (2).

[0147] Example aspect 13: The apparatus according to example aspect 12, wherein the odd number of fingers per unit comprises: The second group of three fingers; and Two of the fingers in the fourth group of fingers.

[0148] Example aspect 14: The apparatus according to example aspect 11, wherein: Each unit contains an odd number of fingers, including seven fingers; and The multiples of the target wavelength include multiples of three (3).

[0149] Example aspect 15: The apparatus according to example aspect 14, wherein the odd number of fingers per unit comprises: The second group of four fingers; and The third finger in the fourth group of fingers.

[0150] Example aspect 16: The apparatus according to example aspect 11, wherein: Each unit contains an odd number of fingers, including nine fingers; and The multiples of the target wavelength include multiples of four (4).

[0151] Example aspect 17: The apparatus according to example aspect 16, wherein the odd number of fingers per unit comprises: The five fingers in the second group of fingers; and The fourth group of fingers consists of four fingers.

[0152] Example aspect 18: The apparatus according to any one of the foregoing example aspects, wherein: The dual-mode surface acoustic wave filter includes at least one piezoelectric layer; The at least one interdigitated transducer is disposed on the at least one piezoelectric layer; and The at least one piezoelectric layer comprises a material having a positive reflection sign for the electrodes of the dual-mode surface acoustic wave filter.

[0153] Example aspect 19: The apparatus according to example aspect 18, wherein the material having the positive reflection symbol comprises lithium niobate (LiNbO3)122 (LN122).

[0154] Example aspect 20: The apparatus according to any one of the foregoing example aspects, wherein: The at least one interdigital transducer includes a single interdigital transducer; and The single interdigital transducer includes: Including the first sub-interdigital transducer of the first set of fingers; and The second sub-interdigital transducer includes the second set of fingers.

[0155] Example aspect 21: The apparatus according to any one of the foregoing example aspects, wherein: The at least one interdigital transducer includes a first interdigital transducer; The dual-mode surface acoustic wave filter includes: Second interdigital transducer; Third interdigital transducer; First reflector; and Second reflector; and The first interdigital transducer, the second interdigital transducer, and the third interdigital transducer are disposed between the first reflector and the second reflector.

[0156] Example aspect 22: The apparatus according to example aspect 21, wherein: The dual-mode surface acoustic wave filter includes grating spacers, each grating spacer comprising at least one metal strip that extends substantially parallel to the plurality of fingers of the first interdigital transducer across the dual-mode surface acoustic wave filter; and The grid separator is positioned between the first interdigital transducer and the second interdigital transducer.

[0157] Example aspect 23: The apparatus according to example aspect 21 or 22, wherein: The second interdigital transducer includes a third bus, a fourth bus, and a plurality of other fingers extending from the third bus toward the fourth bus, the plurality of other fingers including: A third group of finger-like objects possessing third-space properties; and A fourth set of fingers having a fourth spatial attribute different from the third spatial attribute, wherein the fourth spatial attribute includes at least two fingers in the fourth set of fingers being positioned adjacent to each other.

[0158] Example aspect 24: The apparatus according to example aspect 23, wherein the fourth set of fingers of the second interdigital transducer is physically closer to the second set of fingers of the first interdigital transducer than to the third set of fingers of the second interdigital transducer.

[0159] Example aspect 25: The apparatus according to example aspect 23 or 24, wherein: The third spatial property of the third group of finger-like structures includes: There are no adjacent fingers in the third group of fingers; and The spacing of the third set of fingers; and The third spatial attribute of the third group of fingers is substantially equivalent to the first spatial attribute of the first group of fingers.

[0160] Example aspect 26: The apparatus according to any one of example aspects 23 to 25, wherein: The second set of fingers includes a first number of fingers in each of the plurality of units of the first interdigital transducer; and The fourth group of fingers includes a second number of fingers in each of the multiple units of the second interdigital transducer, wherein the first number of fingers in each unit is different from the second number of fingers in each unit.

[0161] Example aspect 27: The apparatus according to any one of the foregoing example aspects further includes: A wireless transceiver coupled to at least one antenna, the wireless transceiver including the dual-mode surface acoustic wave filter and configured to use the dual-mode surface acoustic wave filter to filter wireless signals transmitted via the at least one antenna.

[0162] Example aspect 28: A method for manufacturing a dual-mode surface acoustic wave filter, the method comprising: A first set of fingers is provided for at least one interdigital transducer of the dual-mode surface acoustic wave filter, the first set of fingers extending from a first busbar of the at least one interdigital transducer toward a second busbar of the at least one interdigital transducer, the first set of fingers having a first spatial property; and The dual-mode surface acoustic wave filter provides a second set of fingers for at least one interdigital transducer, the second set of fingers extending from the first busbar toward the second busbar, the second set of fingers having a second spatial property different from the first spatial property, the second spatial property including at least two fingers in the second set of fingers being positioned adjacent to each other.

[0163] Example aspect 29: The method described according to example aspect 28, wherein: The first spatial attribute includes an even number of fingers per unit in a first region comprising the first set of fingers of the at least one interdigital transducer; and The second spatial attribute includes an odd number of fingers per unit in the second region of the second set of fingers of the at least one interdigital transducer.

[0164] Example aspect 30: An apparatus comprising: A dual-mode surface acoustic wave (SAW) filter, the dual-mode SAW filter comprising at least one interdigital transducer, the at least one interdigital transducer comprising: A first region comprising a plurality of fingers arranged such that fingers from different buses of the at least one interdigitated transducer alternate, the plurality of fingers in the first region having a first spacing; and The second region includes a plurality of other fingers arranged to include at least two adjacent fingers extending from the same busbar of the at least one interdigital transducer, the plurality of other fingers in the second region having a second spacing different from the first spacing.

[0165] The terms “first,” “second,” “third,” and other numerically related indicators are used herein to identify or distinguish items that are similar or related to each other in a given context (such as a particular embodiment, a single diagram, a given component, or a claim). Thus, a first item in one context may differ from a first item in another context. For example, an item identified as “first interdigital transducer” in one context may be identified as “second interdigital transducer” in another context. Similarly, “first set of fingers” or “first spatial property” in one claim may be referred to as “second set of fingers” or “third spatial property” in different claims, respectively. Furthermore, “third set of fingers” in one claim may differ from “third set of fingers” in another claim (e.g., being part of a different interdigital transducer).

[0166] Unless the context otherwise specifies, the use of the word “or” in this document can be interpreted as “inclusive or” or as the use of a term that allows the inclusion or application of one or more items linked by the word “or” (e.g., the phrase “A or B” can be interpreted as allowing only “A”, only “B”, or both “A” and “B”). Additionally, as used herein, the phrase “at least one of” in a list of items refers to any combination of those items (including single members). For example, “at least one of a, b, or c” can cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c). Furthermore, the items represented in the figures and the terms discussed herein can indicate one or more items or terms, and therefore, the singular or plural forms of these items and terms can be referred to interchangeably in this written description.

[0167] Finally, although the subject matter has been described in language specific to structural features or methodological operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or operations described above. This includes not being limited to the organization or combination of the features or the order in which the operations are performed. Rather, these specific features and methods are disclosed as exemplary embodiments for implementing a two-mode surface acoustic wave (SAW) filter with a modulated interdigital transducer.

Claims

1. An apparatus, the apparatus comprising: A dual-mode surface acoustic wave (SAW) filter, comprising: At least one interdigital transducer, the at least one interdigital transducer including a first busbar, a second busbar, and a plurality of fingers extending from the first busbar toward the second busbar, the plurality of fingers including: The first group of finger-like objects possessing the first spatial property; and A second set of fingers having a second spatial attribute different from the first spatial attribute, wherein the second spatial attribute includes at least two fingers in the second set of fingers being positioned adjacent to each other.

2. The apparatus according to claim 1, wherein: The first spatial attribute includes the first spacing between the first set of fingers; and The second spatial attribute includes a second spacing between the second set of fingers, which is different from the first spacing.

3. The apparatus according to claim 1, wherein: The first spatial attribute includes the first metallization ratio of the first set of fingers; and The second spatial attribute includes a second metallization ratio of the second set of fingers, which is different from the first metallization ratio.

4. The apparatus of claim 1, wherein the first spatial attribute of the first group of fingers includes the absence of adjacent fingers in the first group of fingers.

5. The apparatus of claim 1, wherein the second set of fingers is positioned adjacent to the first set of fingers along the first busbar of the at least one interdigital transducer.

6. The apparatus according to claim 1, wherein: The at least one interdigital transducer includes a plurality of other fingers extending from the second busbar toward the first busbar, the plurality of other fingers including: A third group of finger-like objects possessing the first spatial attribute; and A fourth set of fingers having a third spatial property, the third spatial property including at least two fingers in the fourth set of fingers being separated by a gap sufficient to allow at least two fingers in the second set of fingers that are positioned adjacent to each other to be positioned between at least two fingers in the fourth set of fingers.

7. The apparatus of claim 6, wherein at least two of the fourth set of fingers are not adjacent to each other, but are continuous along the second generatrix.

8. The apparatus according to claim 6, wherein: The combination of the second group of fingers and the fourth group of fingers has an odd number of fingers in each of the plurality of units of the at least one interdigital transducer; and The width of each of the plurality of cells is based on the target wavelength.

9. The apparatus of claim 8, wherein the at least one interdigital transducer comprises: At least one of the plurality of units having an odd number of fingers in each unit, the at least one unit comprising fingers having the second spatial attribute and the third spatial attribute; and At least one partial unit of the plurality of units has fewer fingers than the odd number of fingers in each unit, the at least one partial unit comprising two or more fingers corresponding to at least one of the second spatial attribute or the third spatial attribute.

10. The apparatus of claim 8, wherein the width of each of the plurality of units is based on a multiple of the target wavelength.

11. The apparatus according to claim 1, wherein: The dual-mode surface acoustic wave filter includes at least one piezoelectric layer; The at least one interdigitated transducer is disposed on the at least one piezoelectric layer; and The at least one piezoelectric layer comprises a material having a positive reflection sign for the electrodes of the dual-mode surface acoustic wave filter.

12. The apparatus of claim 11, wherein the material having the positive reflection symbol comprises lithium niobate (LiNbO3)122 (LN122).

13. The apparatus according to claim 1, wherein: The at least one interdigital transducer includes a single interdigital transducer; and The single interdigital transducer includes: Including the first sub-interdigital transducer of the first set of fingers; and The second sub-interdigital transducer includes the second set of fingers.

14. The apparatus according to claim 1, wherein: The at least one interdigital transducer includes a first interdigital transducer; The dual-mode surface acoustic wave filter includes: Second interdigital transducer; Third interdigital transducer; First reflector; and Second reflector; and The first interdigital transducer, the second interdigital transducer, and the third interdigital transducer are disposed between the first reflector and the second reflector.

15. The apparatus according to claim 14, wherein: The dual-mode surface acoustic wave filter includes grating spacers, each grating spacer comprising at least one metal strip that extends substantially parallel to the plurality of fingers of the first interdigital transducer across the dual-mode surface acoustic wave filter; and The grid separator is positioned between the first interdigital transducer and the second interdigital transducer.

16. The apparatus according to claim 14, wherein: The second interdigital transducer includes a third bus, a fourth bus, and a plurality of other fingers extending from the third bus toward the fourth bus, the plurality of other fingers including: A third group of finger-like objects possessing third-space properties; and A fourth set of fingers having a fourth spatial attribute different from the third spatial attribute, wherein the fourth spatial attribute includes at least two fingers in the fourth set of fingers being positioned adjacent to each other.

17. The apparatus according to claim 16, wherein: The third spatial property of the third group of finger-like structures includes: The third group of fingers does not contain any adjacent fingers; and The spacing of the third set of fingers; and The third spatial attribute of the third group of fingers is substantially equivalent to the first spatial attribute of the first group of fingers.

18. The apparatus of claim 16, wherein: The second set of fingers includes a first number of fingers in each of the plurality of units of the first interdigital transducer; and The fourth group of fingers includes a second number of fingers in each of the multiple units of the second interdigital transducer, wherein the first number of fingers in each unit is different from the second number of fingers in each unit.

19. A method for manufacturing a dual-mode surface acoustic wave filter, the method comprising: A first set of fingers is provided for at least one interdigital transducer of the dual-mode surface acoustic wave filter, the first set of fingers extending from a first busbar of the at least one interdigital transducer toward a second busbar of the at least one interdigital transducer, the first set of fingers having a first spatial property. as well as The dual-mode surface acoustic wave filter provides a second set of fingers for at least one interdigital transducer, the second set of fingers extending from the first busbar toward the second busbar, the second set of fingers having a second spatial property different from the first spatial property, the second spatial property including at least two fingers in the second set of fingers being positioned adjacent to each other.

20. An apparatus comprising: A dual-mode surface acoustic wave (SAW) filter, the dual-mode SAW filter comprising at least one interdigital transducer, the at least one interdigital transducer comprising: A first region comprising a plurality of fingers arranged such that fingers from different buses of the at least one interdigitated transducer alternate, the plurality of fingers in the first region having a first spacing; and The second region includes a plurality of other fingers arranged to include at least two adjacent fingers extending from the same busbar of the at least one interdigital transducer, the plurality of other fingers in the second region having a second spacing different from the first spacing.

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