Improved structure for improving power of SAW filter

Abstract

The utility model discloses an improved structure for improving SAW filter power, which comprises a plurality of SAW filters, each SAW filter is of an MMS structure, the plurality of SAW filters are connected in series to form a series SAW filter bank, and the plurality of series SAW filter banks are connected in parallel to form a cascade SAW filter bank. According to the improved design of the scheme, the acceptable working current and working voltage are greatly improved, so that the power of the whole SAW filter is correspondingly and greatly improved, the SAW filter can work at a receiving end or a transmitting end, the applicable use scene is expanded, and meanwhile, the anti-interference capability is also enhanced through power improvement.

Description

Technical Field

[0001] The utility model relates to the technical field of filters, in particular to an improved structure for increasing the power of a SAW filter. Background Art

[0002] SAW (surface acoustic wave) filter is an elastic wave filter that uses sound waves to propagate on the surface of a piezoelectric substrate material. When an electrical signal is applied to the polished surface of the substrate material, surface acoustic waves propagating along the surface are excited. These sound waves are subject to specific reflections and interference during the propagation process, thereby achieving a filtering function. IDT is the core component of the SAW filter. It consists of a series of alternating metal electrodes (usually aluminum or gold) that are shaped like crossed fingers, hence the name interdigital transducer. These electrodes are deposited on a piezoelectric substrate, and when an alternating electrical signal is applied to the IDT, it excites surface acoustic waves on the piezoelectric substrate. Similarly, when the surface acoustic wave propagates to the IDT, it is also converted into an electrical signal.

[0003] SAW filters are generally LAD (ladder) structures or MMS (multi-mode) structures. Compared with LAD structures, MMS has the advantages of high out-of-band suppression and compact structure, and is one of the commonly used SAW filter technologies. However, the input voltage of the MMS structure is directly loaded on the primary IDT, and the power it can withstand is relatively low. It can only be used at the receiving end, and there are few means to increase its power. Utility Model Content

[0004] The utility model aims to overcome the defect that when the SAW filter in the prior art adopts the MMS structure, the power transfer borne by the IDT can only be used at the receiving end and has great limitations in use, and to provide an improved structure for increasing the power of the SAW filter.

[0005] The purpose of this utility model is achieved through the following technical solutions:

[0006] The improved structure for improving the power of SAW filter comprises several SAW filters, the SAW filters are of MMS structure, several SAW filters are connected in series to form a series SAW filter group, and several series SAW filter groups are connected in parallel to form a cascade SAW filter group.

[0007] The rated operating current and rated operating voltage of a single SAW filter are fixed values. Compared with the filtering work of a single SAW filter, the series SAW filter group designed in this scheme has N series filters in it, and the overall acceptable operating voltage is M times. Similarly, the acceptable operating current of the N parallel series SAW filter group is M times. Compared with the filtering work of a single SAW filter, the acceptable operating current and operating voltage of the improved design of this scheme are greatly improved. Therefore, the power of the overall SAW filter is also greatly improved accordingly, and it can work at the receiving end or the transmitting end, expanding the applicable usage scenarios. At the same time, the power increase also enhances the anti-interference ability.

[0008] Preferably, there are at least four SAW filters, two SAW filters are connected in series to form a series SAW filter group, and two series SAW filter groups are connected in parallel to form a cascade SAW filter group.

[0009] Compared with a conventional single SAW filter that performs the same work requirements, the design of this solution has a voltage on each SAW filter that is 1 / 2 of that of a conventional single SAW filter, and the current is also 1 / 2 of that of a conventional single SAW filter, that is, the power is 1 / 4. Therefore, overall, the design of this solution increases the power of a conventional single SAW filter by 6dBm.

[0010] Preferably, the cascaded SAW filter group is also connected in series with a single SAW filter.

[0011] Preferably, the number of the cascaded SAW filter groups is n, and the n cascaded SAW filter groups are connected in series.

[0012] Preferably, the number of the SAW filters is n. 2 n SAW filters are connected in series to form a series SAW filter group, and the number of the series SAW filter group is also n.

[0013] The voltage loaded on each IDT becomes 1 / n of the original structure, and the current passing through it becomes 1 / n of the original structure, so that the power borne by each IDT becomes 1 / n of the original 2 , the power of the entire filter is n of the original single-stage structure 2 times, that is, the power is increased by 20logn times, that is, when n=2, the power is increased by 6dBm, and when n=3, the power is increased by 9.54dBm.

[0014] The beneficial effects of the present invention are as follows: the rated operating current and rated operating voltage of a single SAW filter are fixed values. Compared with the filtering work of a single SAW filter, the series SAW filter group designed in this scheme has N series-connected filters, and the overall acceptable operating voltage is M times. Similarly, the acceptable operating current of the N parallel series SAW filter group is M times. Compared with the filtering work of a single SAW filter, the acceptable operating current and operating voltage of the improved design of this scheme are greatly improved. Therefore, the power of the overall SAW filter is also greatly improved accordingly, and it can work at the receiving end or the transmitting end, expanding the applicable usage scenarios. At the same time, the power increase also enhances the anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a first structural schematic diagram of the utility model;

[0016] Figure 2 This is a structural schematic diagram of a single SAW filter of the utility model;

[0017] Figure 3 This is another structural schematic diagram of a single SAW filter of the utility model;

[0018] Figure 4 It is a second structural schematic diagram of the utility model;

[0019] Figure 5 yes Figure 1 A specific structural schematic diagram of;

[0020] Figure 6 It is a third structural schematic diagram of the utility model;

[0021] Figure 7 This is a fourth structural schematic diagram of the utility model;

[0022] Figure 8 This is a fifth structural schematic diagram of the utility model;

[0023] Fig. 9 It is a transmission characteristic schematic diagram of the utility model;

[0024] Fig.10 Another transmission characteristic schematic diagram of the utility model. DETAILED DESCRIPTION

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0026] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0027] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0028] Embodiment 1:

[0029] The improved structure for improving the power of SAW filter comprises several SAW filters, the SAW filters are of MMS structure, several SAW filters are connected in series to form a series SAW filter group, and several series SAW filter groups are connected in parallel to form a cascade SAW filter group.

[0030] The voltage loaded on each IDT becomes 1 / n of the original structure, and the current passing through it becomes 1 / n of the original structure, so that the power borne by each IDT becomes 1 / n of the original 2 , the power of the entire filter is n of the original single-stage structure 2 times, that is, the power is increased by 20logn times, that is, when n=2, the power is increased by 6dBm, and when n=3, the power is increased by 9.54dBm.

[0031] The rated operating current and rated operating voltage of a single SAW filter are fixed values. Compared with the filtering work of a single SAW filter, the series SAW filter group designed in this scheme has N series filters in it, and the overall acceptable operating voltage is M times. Similarly, the acceptable operating current of the N parallel series SAW filter group is M times. Compared with the filtering work of a single SAW filter, the acceptable operating current and operating voltage of the improved design of this scheme are greatly improved. Therefore, the power of the overall SAW filter is also greatly improved accordingly, and it can work at the receiving end or the transmitting end, expanding the applicable usage scenarios. At the same time, the power increase also enhances the anti-interference ability.

[0032] Specifically, Figure 1As shown in FIG. 1 , there are four SAW filters F1, two SAW filters are connected in series to form a series SAW filter group, and two series SAW filter groups are connected in parallel to form a cascade SAW filter group. The transmission characteristic diagram of the filter is shown in FIG. Fig. 9 shown.

[0033] Compared with a conventional single SAW filter that performs the same work requirements, the design of this solution has a voltage on each SAW filter that is 1 / 2 of that of a conventional single SAW filter, and the current is also 1 / 2 of that of a conventional single SAW filter, that is, the power is 1 / 4. Therefore, overall, the design of this solution increases the power of a conventional single SAW filter by 6dBm.

[0034] Figure 2 This is a schematic diagram of the structure of the SAW filter using the MMS structure, which uses the 1-3 mode MMS structure. Figure 3 This is another structural diagram of the SAW filter using the MMS structure. It uses the 1-3-5 mode MMS structure, and can also use the 1-3-5-7 mode or more modes of MMS structure. It can be flexibly selected according to actual needs. Figure 5 This is a specific structural diagram of the MMS structure of mode 1-3 adopted in this embodiment.

[0035] Embodiment 2:

[0036] The improved structure for improving the power of the SAW filter has the same principle and implementation method as that of the first embodiment, except that Figure 4 As shown, the SAW filter can be formed by connecting two SAW filters with MMS structure in parallel. The specific structure of the two SAW filters with MMS structure can be adopted. Figure 2 or Figure 3 The structure shown.

[0037] Embodiment 3:

[0038] The improved structure for improving the power of the SAW filter has the same principle and implementation method as that of the first embodiment, except that Figure 6 As shown in Figure 1, the cascaded SAW filter group is also connected in series with a single SAW filter. The transmission characteristic diagram of the filter is shown in Figure 1. Fig.10 shown.

[0039] Embodiment 4:

[0040] The improved structure for improving the power of the SAW filter has the same principle and implementation method as that of the first embodiment, except that Figure 7 As shown in FIG. 1 , the number of cascaded SAW filter groups is 2, and the two cascaded SAW filter groups are connected in series. The transmission characteristic diagram of the filter is shown in FIG. Fig.10 shown.

[0041] Embodiment 5:

[0042] The improved structure for improving the power of the SAW filter has the same principle and implementation method as that of the first embodiment, except that Figure 8 As shown in FIG. 1 , the number of SAW filters is 9, and 3 SAW filters are connected in series to form a series SAW filter group, and the number of series SAW filter groups is also 3. The transmission characteristic diagram of the filter is shown in FIG. Fig. 9 shown.

[0043] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0044] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. An improved structure for increasing the power of a SAW filter, characterized in that: It comprises several SAW filters, the SAW filters are of MMS structure, several SAW filters are connected in series to form a series SAW filter group, and several series SAW filter groups are connected in parallel to form a cascade SAW filter group.

2. The improved structure for increasing the power of a SAW filter according to claim 1 is characterized in that: There are at least four SAW filters, two SAW filters are connected in series to form a series SAW filter group, and two series SAW filter groups are connected in parallel to form a cascade SAW filter group.

3. The improved structure for increasing the power of a SAW filter according to claim 2 is characterized in that: The cascaded SAW filter bank is also connected in series with a single SAW filter.

4. The improved structure for increasing the power of a SAW filter according to claim 2 is characterized in that: The number of the cascaded SAW filter groups is n, and the n cascaded SAW filter groups are connected in series.

5. The improved structure for increasing the power of a SAW filter according to claim 1 is characterized in that: The number of SAW filters is n 2 n SAW filters are connected in series to form a series SAW filter group, and the number of the series SAW filter group is also n.

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