A diplexer
By designing multiple series resonators with different pitches and pitch widths in a duplexer, and combining them with a trapezoidal filter structure, the problem of insufficient isolation characteristics in the miniaturization process of the duplexer is solved, achieving higher isolation characteristics and smaller size.
Patent Information
- Application Number
- CN202610122177.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-01-30
- Filing Date
- 2026-01-29
- Publication Date
- 2026-07-31
AI Technical Summary
In the prior art, duplexers have difficulty improving the isolation characteristics between the transmitting and receiving filters while achieving miniaturization, and the need for additional band-stop filters prevents further miniaturization.
By designing multiple series resonators of the transmitting filter in a duplexer, and using electrode index configurations with different pitches and pitch widths, including series resonators with first and second pitches, combined with a trapezoidal filter structure, the isolation characteristics are improved.
Without increasing the size of the duplexer, the isolation characteristics between the transmitting and receiving filters are significantly improved, achieving higher isolation and a smaller size.
Smart Images
Figure CN122496008A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a duplexer. Background Technology
[0002] With technological advancements in recent years, smartphones and other mobile communication terminals have achieved significant miniaturization and weight reduction. As a result, duplexers used in these mobile communication terminals have been adopted, enabling miniaturization. Furthermore, with the rapid increase in mobile communication systems that simultaneously transmit and receive data, the demand for duplexers has also grown dramatically.
[0003] With the evolution of mobile communication systems, the requirements for duplexers are becoming increasingly stringent. In other words, compared to the past, they are required to have superior characteristics and be further miniaturized.
[0004] In particular, higher isolation characteristics are required between the transmitting and receiving filters of a duplexer.
[0005] Patent Document 1 (Japanese Patent Application Publication No. 2012-501564) discloses a method for improving the isolation between a duplexer and two filters. This method involves coupling a receiving filter to an antenna terminal via a band-stop filter within the duplexer. This band-stop filter separates the transmitting path from the receiving path, thereby improving the isolation of the duplexer. Summary of the Invention
[0006] However, in Patent Document 1, an additional band-stop filter is required, which makes miniaturization impossible.
[0007] This disclosure is made to address the aforementioned problems. The purpose of this disclosure is to provide a duplexer with improved isolation characteristics and miniaturized design.
[0008] The duplexers disclosed herein include: Receiver filter Transmitting filter And antenna terminals, The transmitting filter has multiple series resonators and multiple parallel resonators. The plurality of series resonators include IDT electrodes comprising electrode fingers configured with a predetermined pitch. The plurality of series resonators include: A first series resonator comprising a first pitch and a second pitch with a pitch width greater than the first pitch. And a second series resonator comprising a third pitch and a fourth pitch with a pitch width smaller than the third pitch, Wherein, the ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the second pitch is less than the ratio of the electrode index of the third pitch to the sum of the electrode indices of the third pitch and the fourth pitch.
[0009] In some embodiments, the ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the second pitch is less than half the ratio of the electrode index of the third pitch to the sum of the electrode indices of the third pitch and the fourth pitch.
[0010] In some implementations, the difference in pitch width between the first pitch and the second pitch is greater than the difference in pitch width between the third pitch and the fourth pitch.
[0011] In some implementations, the difference between the pitch width of the first pitch and the second pitch is more than twice the difference between the pitch width of the third pitch and the fourth pitch.
[0012] In some implementations, the ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the second pitch is less than one-fifth.
[0013] In some implementations, the first series resonator is positioned in a stage further away from the antenna terminal than the second series resonator.
[0014] In some implementations, the transmitting filter and the receiving filter are trapezoidal filters.
[0015] In some implementations, the duty cycle of the electrode fingers of the first pitch, the second pitch, the third pitch, and the fourth pitch is 50%.
[0016] According to this disclosure, the isolation characteristics of the duplexer can be improved, and miniaturization can be achieved. Attached Figure Description
[0017] Figure 1 This is a longitudinal sectional view of the duplexer in the embodiment.
[0018] Figure 2 An example diagram is provided to illustrate the duplexer in the embodiment having an elastic wave device (resonator).
[0019] Figure 3 A schematic circuit diagram of the duplexer 20 in the embodiment is shown.
[0020] Figure 4 A diagram illustrating the pitch modulation of the series resonator S3 of the transmitting filter 30 of the duplexer 20 in the embodiment.
[0021] Figure 5 A diagram illustrating the pitch modulation of the series resonator S4 of the transmitting filter 30 of the duplexer 20 in the embodiment.
[0022] Figure 6 A diagram illustrating the pitch modulation of the series resonator of the transmitting filter of the duplexer 20 in a comparative example of the embodiment.
[0023] Figure 7 A graph is provided to illustrate the resonance characteristics of the series resonator S3 of the duplexer 20 in the embodiment and the series resonator RS3 of the duplexer in the comparative example.
[0024] Figure 8 A diagram illustrating the isolation characteristics of the duplexer 20 in the embodiment and the duplexer in the comparative example.
[0025] Figure 9 A graph showing the throughput characteristics of the duplexer 20 in the embodiment and the duplexer in the comparative example.
[0026] Figure label: 20 duplexers 23 Wiring board 24 External connection terminals 25 Device Chips 26 Electrode pads 27 bumps 28 Sealing section 29 gaps 30 Transmit Filter 40 Receiver Filter 52 Elastic Wave Devices 52a IDT electrode 52b reflector 52c comb-shaped electrode 52d electrode finger 52e Busbar.
[0027] The embodiments will now be described with reference to the accompanying drawings. It should be noted that in the various figures, the same or corresponding parts are given the same reference numerals, and repeated descriptions of these parts will be appropriately simplified or omitted. Detailed Implementation
[0028] Figure 1 This is a longitudinal sectional view of the duplexer in the embodiment.
[0029] like Figure 1 As shown, the duplexer 20 includes a wiring board 23, an external connection terminal 24, a device chip 25, an electrode pad 26, a bump 27, and a sealing part 28.
[0030] For example, wiring substrate 23 is a multilayer substrate made of resin. For example, wiring substrate 23 is a low temperature co-fired ceramic (LTCC) multilayer substrate made of multiple dielectric layers.
[0031] Multiple external connection terminals 24 are formed on the underside of the wiring board 23.
[0032] Multiple electrode pads 26 are formed on the main surface of the wiring substrate 23. For example, the electrode pads 26 are formed of copper or a copper-containing alloy. For example, the thickness of the electrode pads 26 is 10 μm to 20 μm.
[0033] Bumps 27 are formed on the upper surface of each electrode pad 26. For example, bumps 27 are gold bumps. For example, the height of bumps 27 is 10 μm to 50 μm.
[0034] A gap 29 is formed between the wiring substrate 23 and the device chip 25.
[0035] The device chip 25 is mounted on the wiring substrate 23 via bumps 27 using a flip-chip bonding method. The device chip 25 is electrically connected to multiple electrode pads 26 via multiple bumps 27.
[0036] Device chip 25 is, for example, a surface elastic wave device chip. Device chip 25 includes a piezoelectric substrate formed of a piezoelectric material. The piezoelectric substrate is a substrate formed of a piezoelectric single crystal such as lithium niobate, lithium tantalate, or quartz.
[0037] The thickness of the piezoelectric substrate can be, for example, from 100 μm to 300 μm.
[0038] According to another example, the device chip 25 is a substrate formed by bonding a piezoelectric substrate to a support substrate. The support substrate is, for example, a substrate formed of sapphire, silicon, alumina, spinel, quartz, or glass. In this case, the thickness of the piezoelectric substrate can be, for example, from 0.3 μm to 5 μm.
[0039] An elastic wave device is formed on a piezoelectric substrate. On the main surface of the device chip 25, a duplexer comprising multiple elastic wave devices is formed, the duplexer including a transmitting filter and a receiving filter.
[0040] Transmitting filters are constructed to allow electrical signals in the desired frequency band to pass through. For example, a transmitting filter is a trapezoidal filter consisting of multiple series resonators and multiple parallel resonators.
[0041] The receiving filter is designed to allow electrical signals in the desired frequency band to pass through. For example, the receiving filter is a trapezoidal filter.
[0042] The sealing portion 28 is formed to cover the device chip 25. For example, the sealing portion 28 is formed of an insulator such as a synthetic resin. For example, the sealing portion 28 is formed of a metal.
[0043] When the sealing portion 28 is formed of a synthetic resin, the synthetic resin may be, for example, epoxy resin, polyimide, etc. The sealing portion 28 is preferably made of epoxy resin and is formed by a low-temperature curing process. A gap 29 is formed in the region where the wiring substrate 23 faces the device chip 25.
[0044] Next, refer to Figure 2 An example of an elastic wave device 52 formed on device chip 25 will be described. Figure 2 A diagram illustrating an example of the elastic wave device 52 (resonator) of the duplexer 20 in the embodiment.
[0045] like Figure 2 As shown, IDT (Interdigital Transducer) electrodes 52a and a pair of reflectors 52b are formed on the main surface of the device chip 25. The IDT electrodes 52a and the pair of reflectors 52b are configured to excite elastic waves (mainly SH waves).
[0046] For example, the IDT electrode 52a and the pair of reflectors 52b are formed of an alloy of aluminum and copper. Alternatively, the IDT electrode 52a and the pair of reflectors 52b may also be formed of suitable metals or alloys of these metals, such as aluminum, molybdenum, iridium, tungsten, cobalt, nickel, ruthenium, chromium, strontium, titanium, palladium, and silver.
[0047] For example, the IDT electrode 52a and the pair of reflectors 52b are formed of a stacked metal film consisting of multiple metal layers. For example, the thickness of the IDT electrode 52a and the pair of reflectors 52b is 150 nm to 450 nm.
[0048] IDT electrode 52a includes a pair of comb-shaped electrodes 52c. The pair of comb-shaped electrodes 52c are arranged opposite to each other. The comb-shaped electrodes 52c include a plurality of electrode fingers 52d and a bus bar 52e.
[0049] Multiple electrode fingers 52d are aligned along their long sides. Busbar 52e connects the multiple electrode fingers 52d together.
[0050] One of a pair of reflectors 52b is adjacent to one side of the IDT electrode 52a, and the other is adjacent to the other side of the IDT electrode 52a.
[0051] Next, refer to Figure 3 An example of a bandpass filter formed on device chip 25 will be explained. Figure 3 A schematic circuit diagram of the duplexer 20 in the embodiment is shown.
[0052] like Figure 3 As shown, the duplexer 20 includes a transmit filter 30, a receive filter 40, an antenna terminal ANT, a transmit terminal Tx, a receive terminal Rx, and a ground terminal Gnd.
[0053] The transmitting filter 30 includes multiple series resonators S1 to S5 and multiple parallel resonators P1 to P4. The receiving filter 40 includes multiple series resonators S6 to S9 and multiple parallel resonators P5 to P7. Furthermore, both the transmitting filter 30 and the receiving filter 40 are trapezoidal filters.
[0054] The duplexer 20 is, for example, a duplexer for LTE band 2. The passband of the transmit filter 30 is 1850MHz to 1910MHz. The passband of the receive filter 40 is 1930MHz to 1990MHz.
[0055] Figure 4 This diagram illustrates the pitch modulation of the series resonator S3 of the transmit filter 30 of the duplexer 20 in the embodiment. The numbers on the horizontal axis represent the electrode pair numbers with the resonator center at 0. The central box represents the IDT electrode region, and the left and right boxes represent the reflector regions. Furthermore, the vertical axis represents the electrode pitch in μm.
[0056] In the first pitch region R1 of the IDT electrodes of the series resonator S3, represented by region R1, the pitch is 2.128 μm. The number of electrode finger pairs in the first pitch region R1 is 50 pairs. Furthermore, the duty cycle is 50%.
[0057] In the second pitch region R2 of the IDT electrodes of the series resonator S3, represented by region R2, the pitch is 2.134 μm. The number of electrode finger pairs in the second pitch region R2 is 244 pairs. Furthermore, the duty cycle is 50%.
[0058] Figure 5 This is a diagram illustrating the pitch modulation of the series resonator S4 of the transmitting filter 30 of the duplexer 20 in the embodiment. The horizontal and vertical axes in the diagram are related to... Figure 4 same.
[0059] In the third pitch region R3 of the IDT electrodes of the series resonator S4, represented by region R3, the pitch is 2.128 μm. The number of electrode finger pairs in the third pitch region R3 is 116 pairs. Furthermore, the duty cycle is 50%.
[0060] In the fourth pitch region R4 of the IDT electrodes of the series resonator S4, represented by region R4, the pitch is 2.126 μm. The number of electrode finger pairs in the fourth pitch region R4 is 117 pairs. Furthermore, the duty cycle is 50%.
[0061] Such as combination Figure 4 and Figure 5 As clearly stated in the description, the ratio of the electrode index of the first pitch region R1 to the sum of the electrode indices of the first pitch region R1 and the second pitch region R2 is less than the ratio of the electrode index of the third pitch region R3 to the sum of the electrode indices of the third pitch region R3 and the fourth pitch region R4.
[0062] Furthermore, the ratio of the electrode index of the first pitch region R1 to the sum of the electrode indices of the first pitch region R1 and the second pitch region R2 is less than half the ratio of the electrode index of the third pitch region R3 to the sum of the electrode indices of the third pitch region R3 and the fourth pitch region R4.
[0063] Furthermore, the difference in pitch width between the first pitch region R1 and the second pitch region R2 is greater than the difference in pitch width between the third pitch region R3 and the fourth pitch region R4. Simultaneously, the difference in pitch width between the first pitch region R1 and the second pitch region R2 is more than twice the difference in pitch width between the third pitch region R3 and the fourth pitch region R4. It should be noted that the difference in pitch width refers to the difference expressed as an absolute value, regardless of the sign.
[0064] In addition, such as Figure 4 As shown, the number of electrode finger pairs in the first pitch region R1 is 50 pairs, and the number of electrode finger pairs in the second pitch region R2 is 244 pairs. It can be seen that the ratio of the electrode index of the first pitch region R1 to the sum of the electrode indices of the first pitch region R1 and the second pitch region R2 can be less than one-fifth.
[0065] Furthermore, the series resonator S3 is positioned in a stage that is farther from the antenna terminal ANT than the series resonator S4.
[0066] Figure 6 A diagram illustrating the pitch modulation of the series resonator of the duplexer in a comparative example of the duplexer 20 in the embodiment. Figure 6 (a) is a diagram showing the pitch modulation of the series resonator RS3 in the duplexer of the comparative example, which is located at a position corresponding to the series resonator S3 of the transmitting filter 30 of the duplexer 20 in the embodiment. Figure 6 (b) A diagram illustrating the pitch modulation of the series resonator RS4 in the comparative example duplexer, located at a position corresponding to the series resonator S4 of the transmitting filter 30 of the duplexer 20 in the embodiment. In the comparative example, each series resonator exhibits flat pitch modulation within the IDT electrode region.
[0067] The only difference between series resonator RS3 and series resonator S3 is the pitch modulation in the IDT electrodes; the rest of the structure is the same. The same applies to series resonator RS4 and series resonator S4. Furthermore, since the other structures of the duplexer in the comparative example are the same as those of the duplexer 20 in the embodiment, their description is omitted.
[0068] Figure 7 A diagram is provided to illustrate the resonance characteristics of the series resonator S3 of the duplexer 20 in the embodiment and the series resonator RS3 of the duplexer in the comparative example. The solid line represents the resonance characteristic of the series resonator S3, and the dashed line represents the resonance characteristic of the series resonator RS3.
[0069] like Figure 7 As shown, compared with the resonant characteristics of the series resonator RS3, the resonant characteristics of the series resonator S3 have a smaller attenuation at the poles, but a larger attenuation over a wider range.
[0070] Figure 8 A diagram illustrating the isolation characteristics of the duplexer 20 in the embodiment and the duplexer in the comparative example is provided. Solid lines represent the isolation characteristics of the duplexer 20 in the embodiment, while dashed lines represent the isolation characteristics of the duplexer in the comparative example.
[0071] like Figure 8 As shown, the duplexer 20 in this embodiment exhibits superior isolation characteristics compared to the duplexer in the comparative example. In particular, the isolation characteristics are improved around 1930MHz. This is because two pitch regions are provided in a series resonator, effectively making the series resonator equivalent to two resonators connected in parallel. Consequently, the motor coupling coefficient is reduced, thereby improving the isolation characteristics.
[0072] Figure 9 This diagram illustrates the passband characteristics of the duplexer 20 in the embodiment and the duplexer in the comparative example. Solid lines represent the passband characteristics of the duplexer 20 in the embodiment, and dashed lines represent the passband characteristics of the duplexer in the comparative example. Figure 9 As shown, the passband characteristics of the duplexer 20 in this embodiment are superior to those of the comparative example duplexer. In addition to the improved attenuation characteristics corresponding to the improved isolation around 1930MHz, the attenuation characteristics around 2100MHz are also improved.
[0073] As can be seen from the embodiments described above, the duplexer 20 can improve isolation characteristics without the need for additional band-stop filters or the like. According to the embodiments described above, a duplexer with improved isolation characteristics and miniaturization can be provided.
[0074] While several aspects of at least one embodiment have been described, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art. Such changes, modifications, and improvements are intended to form part of this disclosure and are intended to fall within the scope of this disclosure.
[0075] It should be understood that the implementation of the method and apparatus described herein is not limited to the structural and arrangement details of the constituent elements described above or shown in the accompanying drawings. The method and apparatus can be implemented in other embodiments and can be carried out or performed in various ways.
[0076] The specific embodiments given herein are for illustrative purposes only and are not intended to be limiting.
[0077] The expressions and terms used in this disclosure are for illustrative purposes only and should not be construed as limiting. The use of words such as “comprising,” “having,” “including,” and variations thereof is intended to include the items listed thereafter and their equivalents, as well as any additional items.
[0078] A reference to “or” means that any term described using “or” can be interpreted as referring to one, more, or all of the terms in the record.
[0079] References to front, back, left, right, up, down, horizontal, vertical, front, and back are merely for descriptive convenience. Such references do not imply that the constituent elements of this disclosure are limited to any particular location or spatial orientation. Therefore, the above descriptions and figures are merely illustrative.
Claims
1. A duplexer, comprising: Receiver filter Transmitting filter And antenna terminals, The transmitting filter has multiple series resonators and multiple parallel resonators. The plurality of series resonators include IDT electrodes comprising electrode fingers arranged at a predetermined pitch. The plurality of series resonators A first series resonator comprising a first pitch and a second pitch with a pitch width greater than the first pitch. And a second series resonator comprising a third pitch and a fourth pitch with a pitch width smaller than the third pitch, Wherein, the ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the second pitch is less than the ratio of the electrode index of the third pitch to the sum of the electrode indices of the third pitch and the fourth pitch.
2. The duplexer according to claim 1, wherein, The ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the electrode indices of the second pitch. The ratio of the electrode index of the third pitch to the sum of the electrode indices of the third pitch and the fourth pitch is less than half.
3. The duplexer according to claim 1, wherein, The difference in pitch width between the first pitch and the second pitch is greater than the difference in pitch width between the third pitch and the fourth pitch.
4. The duplexer according to claim 1, wherein, The difference between the pitch width of the first pitch and the second pitch is more than twice the difference between the pitch width of the third pitch and the fourth pitch.
5. The duplexer according to claim 1, wherein, The ratio of the electrode index of the first pitch to the sum of the electrode indices of the first pitch and the second pitch is less than one-fifth.
6. The duplexer according to claim 1, wherein, The first series resonator is located in a stage segment that is farther from the antenna terminal than the second series resonator.
7. The duplexer according to claim 1, wherein, The transmitting filter and the receiving filter are both trapezoidal filters.
8. The duplexer according to claim 1, wherein, The duty cycle of the electrode fingers of the first pitch, the second pitch, the third pitch, and the fourth pitch is 50%.