Method for manufacturing filter, filter, and communication device

Abstract

The invention discloses a filter manufacturing method, a filter and communication equipment. The filter is a surface acoustic wave filter, and the manufacturing method of the filter comprises the steps that an antenna end is arranged in the filter, and the antenna end is used for receiving a plurality of signals; a plurality of second IDTs are arranged in the filter, at least one second IDT is replaced with a first IDT in the filter, the area of the first IDT is larger than that of the second IDT, the first IDT is equivalent to the second IDT, the first IDT comprises a plurality of sub-IDTs connected in series, the number of reflecting gratings of the first IDT is the same as that of reflecting gratings of the second IDT, the cross index quantity of the sub-IDTs is larger than or equal to that of the second IDT, and / or the cross index quantity of the sub-IDTs is larger than or equal to that of the second IDT. The aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT; and an output end is arranged in the filter, and the output end is used for outputting the signal filtered by the first IDT.

Description

Technical Field

[0001] The present application relates to the technical field of electronic devices, and in particular to a method for manufacturing a filter, a filter, and a communication device. Background Art

[0002] With the development of communication technology, the number of communication frequency bands is also gradually increasing. For example, from 4 frequency bands in the 2G era to more than 50 frequency bands in the 5G era. With the increase in the number of communication frequency bands, communication technology has also brought challenges to anti-interference capabilities. In order to improve the anti-interference capabilities of channels in different frequency bands, multiple indicators need to be considered comprehensively. For example, passive intermodulation (PIM) signals are a very important indicator of the anti-interference capability of frequency band communication. Passive intermodulation signals can refer to spurious signals generated by two or more frequency signals in passive devices due to the nonlinear characteristics of the devices. If passive intermodulation signals are not suppressed or processed in time, it will cause more serious harm to the communication system. For example, passive intermodulation signals will reduce the quality of communication signals, increase channel interference in the communication system, and may also limit the coverage of the communication system, reduce data transmission rates, and may even cause system performance degradation or equipment failure.

[0003] In recent years, with the continuous advancement of wireless communication technology, the application scenarios of wireless communication systems have become more diverse and complex. In this context, filters in wireless communication systems play a vital role. Filters can be responsible for effectively separating and filtering signals from different application modules to ensure that each module can receive clear and accurate signals, thereby improving communication efficiency and signal quality. However, in this process, the impact of the passive intermodulation signals generated on the communication system has become increasingly prominent. In the related art, surface acoustic wave (SAW) filters are currently widely used in radio frequency filters, but how to reduce the passive intermodulation signals generated by SAW during the operation of the communication system is still in the exploratory stage. Therefore, how to reduce the passive intermodulation signals generated by SAW filters in communication systems to ensure the overall performance of the communication system needs to be solved urgently. Summary of the invention

[0004] In view of this, the embodiments of the present application are directed to providing a method for manufacturing a filter, a filter, and a communication device.

[0005] In a first aspect, a method for manufacturing a filter is provided, which is a surface acoustic wave filter, and the method for manufacturing the filter includes: setting an antenna end in the filter, the antenna end being used to receive multiple signals; setting multiple second IDTs in the filter, replacing at least one second IDT with a first IDT in the filter, the area of ​​the first IDT being larger than the area of ​​the second IDT, the first IDT being equivalent to the second IDT, the first IDT including multiple sub-IDTs connected in series, the number of reflection gratings of the first IDT being the same as the number of reflection gratings of the second IDT, the number of fork indexes of the sub-IDT being larger than or equal to the number of fork indexes of the second IDT, and / or the aperture length of the sub-IDT being larger than or equal to the aperture length of the second IDT; and setting an output end in the filter, the output end being used to output the signal filtered by the first IDT.

[0006] According to the first aspect, the first IDT is electrically connected to the antenna terminal, and the first IDT includes a first series IDT electrically connected to the antenna terminal, or, if at least one parallel IDT is included between the antenna terminal and the first series IDT, the first IDT includes at least one parallel IDT and the first series IDT.

[0007] According to the first aspect, or any implementation method of the first aspect above, the filter includes at least one filter circuit. When the filter includes multiple filter circuits, the multiple filter circuits are electrically connected in parallel. The antenna end is used to input multiple signals into the at least one filter circuit. The at least one filter circuit is electrically connected to the antenna end. The at least one filter circuit is used to filter the multiple signals to obtain a filtered signal. The filtered signal is a frequency signal that the at least one filter circuit needs to output. The output end is used to output the filtered signal. The at least one filter circuit includes a first IDT.

[0008] According to the first aspect, or any implementation method of the first aspect above, at least one sub-filter circuit and at least one sub-isolation circuit are arranged in the filter, at least one sub-filter circuit and one sub-isolation circuit are connected in parallel, at least one sub-filter circuit is electrically connected to the output end, at least one sub-filter circuit is used to filter multiple signals to obtain a first signal, at least one sub-isolation circuit is electrically connected to the load, at least one sub-isolation circuit is used to filter multiple signals to obtain a second signal, wherein the first signal is a frequency signal that the filter needs to output, and the second signal is a frequency signal different from the frequency of the first signal among the multiple signals received by the antenna end, and a first IDT is arranged in at least one sub-isolation circuit, or a first IDT is arranged in at least one sub-filter circuit and at least one sub-isolation circuit.

[0009] According to the first aspect, or any implementation of the first aspect above, a plurality of sub-IDTs connected in series include a first sub-IDT, the aperture area of ​​the second IDT multiplied by the number of fork fingers of the second IDT multiplied by the first number equals the aperture area of ​​the first sub-IDT, the finger width of the second IDT and the sum of the distances between adjacent fork fingers of the second IDT multiplied by the finger length of the second IDT equals the aperture area of ​​the second IDT, and the first number is related to the number of sub-IDTs included in the first IDT.

[0010] According to the first aspect, or any implementation of the first aspect above, the capacitance of the first IDT is equivalent to that of the second IDT, and the number of sub-IDTs included in the first IDT is related to a first indicator, and the first indicator includes one or more of the following: power capacity of the filter; insertion loss of the filter; stopband suppression of the filter.

[0011] In a second aspect, a filter is provided, the filter being a surface acoustic wave filter, the filter comprising: a piezoelectric substrate;

[0012] The antenna end is arranged on the piezoelectric substrate and electrically connected to the antenna, and the antenna end is used to receive multiple signals; the output signal end is arranged on the piezoelectric substrate, and the signal end is used to output signals; multiple resonators are arranged on the piezoelectric substrate, and each resonator includes an IDT, wherein, among the multiple resonators, the IDT area of ​​the resonator closest to the antenna end is the largest among all the resonators. The antenna end is used to receive multiple signals; the first IDT, the first IDT is used to filter multiple signals, the first IDT includes multiple sub-IDTs connected in series, the first IDT is equivalent to the second IDT, the number of reflection gratings of the first IDT is the same as the number of reflection gratings of the second IDT, the number of cross-indexes of the sub-IDT is greater than or equal to the second IDT, and / or the aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT; the output end is used to output the signal filtered by the first IDT.

[0013] According to the second aspect, the IDT of the resonator closest to the antenna end is the first IDT, the IDTs of other resonators are the second IDT, the first IDT and the second IDT are equivalent, the first IDT includes multiple sub-IDTs connected in series, the number of reflection gratings of the first IDT is the same as the number of reflection gratings of the second IDT, the number of cross-indexes of the sub-IDT is greater than or equal to the second IDT, and / or the aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT.

[0014] According to the second aspect, or any implementation of the second aspect above, the filter includes at least one first filtering circuit, or at least one first filtering circuit and at least one first isolation circuit; the first filtering circuit and the first isolation circuit both include multiple series resonators and multiple parallel resonators, one end of at least one first filtering circuit is connected to the antenna end, and the other end is connected to the output signal end, one end of at least one first isolation circuit is connected to the antenna end, and the other end is connected to the load; the first IDT is the first series IDT electrically connected to the antenna end, or, if at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT includes at least one parallel IDT and the first series IDT.

[0015] According to the second aspect, or any implementation of the second aspect above, when the filter includes at least one first filtering circuit, the first IDT is set on the at least one first filtering circuit; when the filter includes at least one first filtering circuit and at least one first isolation circuit, the first IDT is set on the at least one first isolation circuit, or the first IDT is set on at least one first filtering circuit and at least one first isolation circuit.

[0016] According to the second aspect, or any implementation of the second aspect above, a plurality of sub-IDTs connected in series include a first sub-IDT, the aperture area of ​​the second IDT multiplied by the number of fork fingers of the second IDT multiplied by the first number equals the aperture area of ​​the first sub-IDT, the finger width of the second IDT and the sum of the distances between adjacent fork fingers of the second IDT multiplied by the finger length of the second IDT equals the aperture area of ​​the second IDT, and the first number is related to the number of sub-IDTs included in the first IDT.

[0017] In a third aspect, the present application provides a filter, which may include a filter manufactured by a manufacturing method as described in the first aspect or any one of the possible implementations of the first aspect.

[0018] In a fourth aspect, the present application provides a communication device, which may include a filter as described in the second aspect or any one of the possible implementations of the second aspect.

[0019] The present application proposes a method for manufacturing a filter. The method can replace the second IDT with a first IDT having an area larger than that of the second IDT, so that the node voltage of the sub-IDT in the first IDT is reduced under the condition that the first IDT is equivalent to the second IDT, thereby reducing the passive intermodulation signal generated by the sub-IDT. Since the reduction of the passive intermodulation signal is nonlinear, the intermodulation signal of the first IDT is reduced, thereby improving the overall performance of the communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A flowchart of a method for manufacturing a filter provided in an embodiment of the present application.

[0021] Figure 2A A schematic diagram of an IDT structure provided in an embodiment of the present application.

[0022] Figure 2B A schematic diagram of an IDT structure provided in an embodiment of the present application.

[0023] Figure 2C A schematic diagram of an IDT structure provided in an embodiment of the present application.

[0024] Figure 3 A schematic diagram of a circuit flow of a filter provided in an embodiment of the present application.

[0025] Figure 4A yes Figure 3 A schematic diagram of the distribution of a circuit board diagram corresponding to the circuit shown.

[0026] Figure 4B yes Figure 3 Another schematic diagram of the distribution of circuit boards corresponding to the circuit shown.

[0027] Figure 5A It is a schematic diagram for comparing the distribution of circuit board diagrams provided in an embodiment of the present application.

[0028] Figure 5B It is a schematic diagram for comparing the distribution of circuit board diagrams provided in an embodiment of the present application.

[0029] Figure 5C It is a schematic diagram for comparing the distribution of circuit board diagrams provided in an embodiment of the present application.

[0030] Figure 5D It is a schematic diagram for comparing the distribution of circuit board diagrams provided in an embodiment of the present application.

[0031] Figure 5E It is a schematic diagram for comparing the distribution of circuit board diagrams provided in an embodiment of the present application.

[0032] Figure 6 It is a schematic diagram of a communication system provided in an embodiment of the present application.

[0033] Figure 7 yes Figure 6 Schematic diagram of the performance curve of the passive intermodulation signal test results.

[0034] Figure 8 It is a structural schematic diagram of a filter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field based on the present application belong to the scope of protection of the present application.

[0036] With the development of communication technology, the number of communication frequency bands is also gradually increasing. For example, from 4 frequency bands in the 2G era to more than 50 frequency bands in the 5G era. With the increase in the number of communication frequency bands, communication technology has also brought challenges to anti-interference capabilities. In order to improve the anti-interference capabilities of channels in different frequency bands, multiple indicators need to be considered comprehensively. For example, passive intermodulation signals are a very important indicator of the anti-interference capability of frequency band communication. Passive intermodulation signals refer to spurious signals generated by the nonlinear characteristics of devices when two or more frequency signals are mixed in passive devices (such as filters, couplers, cables, connectors, antennas, etc.). These spurious signals may fall within the receiving frequency band of the communication system, which may cause interference to the system. For example, these spurious signals will reduce the quality of the communication signal, increase the channel interference of the communication system, and may also limit the coverage of the communication system, reduce the data transmission rate, and may even cause system performance degradation or equipment failure.

[0037] Exemplarily, when two RF signals F1 and F2 pass through a nonlinear circuit at the same time, multiple frequency components may be generated, for example, a second-order intermodulation signal or a third-order intermodulation signal. Among these generated multiple intermodulation signals, the third-order intermodulation distortion has the greatest impact on the communication system because its frequency is closest to the original signal and its intensity is relatively high. Among them, the third-order intermodulation signal may be 2*F1-F2. This passive intermodulation signal is an important indicator for measuring the degree of nonlinearity of a linear system, and is also an interference signal that needs to be suppressed as much as possible in a communication system.

[0038] In some cases, if passive intermodulation signals are not suppressed or processed in a timely manner, it will cause harm to the communication system. For example, the presence of passive intermodulation signals will significantly reduce the sensitivity of the receiver, resulting in a decrease in communication quality, which in turn affects the user experience. For example, due to the interference of passive intermodulation signals, the communication system may not be able to accurately transmit data, resulting in an increase in bit error rate, a decrease in data transmission rate, and even communication interruption. For another example, during the transmission of high-power signals, the generation of passive intermodulation signals will aggravate the nonlinear distortion of the system, further affecting the stability and reliability of the communication system.

[0039] As the number of communication frequency bands gradually increases, in order to improve the compatibility of communication equipment with different communication standards, the demand for filters in communication systems is also increasing significantly. According to the different needs of the communication system, filters can be divided into different types of filters according to different needs. For example, a surface acoustic wave filter is a specific type of acoustic wave filter. The surface acoustic wave filter uses the characteristics of sound waves propagating along the surface of the medium. These sound waves are called surface acoustic waves. At present, the widely used RF filter in wireless communication terminals is the SAW filter, which is responsible for receiving and transmitting RF signals of the channel and outputting signals of specific frequencies among the input multiple RF signals. With the advent of 5G communication, SAW filters are required to operate at higher frequencies. Among them, the resonator is a key component in the SAW filter and can be used to achieve specific frequency selectivity functions. In some SAW filters, IDT can also be used as a resonator. IDT can convert electrical energy into acoustic energy, thereby exciting surface acoustic waves on the piezoelectric substrate. Parameters such as the frequency characteristics of IDT, the intensity of the excited surface acoustic wave, and the finger spacing have an important influence on the performance of the surface acoustic wave filter. SAW wave filters have the advantages of low transmission loss, good anti-electromagnetic interference (EMI) performance, high reliability, and small and light device size. Therefore, SAW filters are widely used in mobile communication terminal products.

[0040] SAW filters can include piezo on insulator (POI) SAW and normal SAW, depending on the substrate used. POI uses a high-performance POI substrate. SAW devices made based on POI materials have excellent characteristics such as high frequency, high quality factor (Q) value, low temperature sensitivity and large bandwidth, which can meet the needs of high performance and high integration. Normal SAW is made using traditional LT (LiTaO3, lithium tantalate) wafer substrates. The SAW device made from this substrate has a low quality factor Q value and a low bandwidth, and is generally used in communication systems with low performance requirements.

[0041] In recent years, with the continuous advancement of wireless communication technology, the application scenarios of wireless communication systems have become more diverse and complex. In this context, filters in wireless communication systems play a vital role. They are responsible for effectively separating and filtering the signals of different application modules to ensure that each module can receive clear and accurate signals, thereby improving communication efficiency and signal quality. However, in this process, the problem of passive intermodulation signals has become increasingly prominent.

[0042] For example, when a wireless communication system includes a SAW filter, as the power strength of the input signal increases, the strength of the generated passive intermodulation signal also increases. The passive intermodulation signal can cause serious signal interference to the SAW filter and the wireless communication system. When the input signal is x(t) = Acos(ωt), the output signal is:

[0043] y(t)=α 1 Acos(ωt)+α 1 A 2 Acos 2 (ωt)+α 1 A 3 Acos 3 (ωt)+..., where α 1 Acos(ωt) can represent the first-order intermodulation signal, α 1 A 2 Acos 2 (ωt) can represent the second-order intermodulation signal, α1A 3 Acos 3 (ωt) can represent a third-order intermodulation signal, and so on. A can be the signal amplitude of the input signal x(t). It can be understood that when the signal amplitude increases, the strength of the signal also increases, and the power generated becomes larger and larger. It can be seen from the formula of the output signal y(t) that the amplitude of the third-order intermodulation signal is proportional to the cube of the input signal amplitude A. It can also be understood that the relationship between the increase or decrease in the signal strength of the communication system and the resulting passive intermodulation signal strength is nonlinear. Exemplarily, when the amplitude of the input signal decreases by 1db and the strength of the input signal decreases by 1db, the strength of the third-order intermodulation signal decreases by 3db.

[0044] In the related technology, POI SAW and Normal SAW are currently widely used in RF filters, but how to reduce the passive intermodulation signals generated by POI SAW and Normal SAW during the operation of the communication system is still in the exploration stage. In some communication systems, such as high-power communication systems, the passive intermodulation signals generated by POI SAW and Normal SAW will cause serious interference to the channel of the communication system, thereby reducing the overall performance of the communication system.

[0045] Therefore, how to reduce the passive intermodulation signal generated by the SAW filter in the communication system to ensure the overall performance of the communication system needs to be solved urgently.

[0046] To solve the above problems, the present application proposes a method for manufacturing a filter, which can reduce the node voltage of the sub-IDT under equivalent conditions by adjusting the aperture length and / or the index quantity of the sub-IDT, thereby reducing the passive intermodulation signal generated by the sub-IDT. And because the reduction of the intermodulation signal is nonlinear, the intermodulation signal of the first IDT is reduced, thereby improving the overall performance of the communication system.

[0047] Figure 1 is a flow chart of a method for manufacturing a filter provided in an embodiment of the present application, Figure 1 The filter shown may be a SAW filter.

[0048] Figure 1 It includes steps S110 to S130.

[0049] Step S110: setting an antenna end in the filter, where the antenna end can be used to receive multiple signals.

[0050] In some embodiments, according to different functional requirements of the communication system, antennas can be divided into different types according to the different frequency ranges of the signals received by the antennas. For example, low-frequency antennas can receive long-wave or low-frequency signals usually between 30kHz and 300kHz, medium-frequency antennas can receive short-wave and medium-frequency signals usually between 300kHz and 3MHz, and high-frequency antennas can receive short-wave or high-frequency signals usually between 3MHz and 30MHz.

[0051] It is understandable that based on the functional requirements of the communication system, the signal received by the antenna end of the filter may be a signal within a certain frequency range. Optionally, the frequency range depends not only on the functional requirements of the communication system, but also on the size and structure design of the antenna.

[0052] In some embodiments, the site resources of existing base stations can be utilized. For example, the 5G base station antenna can be integrated with the traditional 2G / 3G / 4G base station antenna to achieve multi-band coverage. Therefore, the received signal of the antenna can also include the frequency requirements of the multi-function module in the communication system, wherein the signals of different frequency bands can be multiple signals.

[0053] Step S120 , setting a plurality of second IDTs in the filter, replacing at least one second IDT with a first IDT in the filter, the area of ​​the first IDT being greater than the area of ​​the second IDT, and the first IDT being equivalent to the second IDT.

[0054] In some embodiments, a plurality of second IDTs may be provided in the filter. During the manufacturing process of the filter, the first IDT may be used to replace one of the second IDTs, or the first IDT may be used to replace a plurality of the second IDTs. Optionally, the area of ​​the first IDT is larger than the area of ​​the second IDT, and the first IDT may be equivalent to the second IDT.

[0055] In some embodiments, the first IDT is equivalent to the second IDT, which can be understood as the capacitance of the first IDT and the second IDT being equivalent. Exemplarily, the first IDT may include two IDTs connected in series, and the equivalent capacitance of the first IDT obtained may be the same as the capacitance of the second IDT. For example, the first IDT may include two IDTs with a capacitance of 2PF, which is equivalent to an IDT with a capacitance of 1PF, and the IDT with a capacitance of 1PF may be the second IDT. In other words, the first IDT may be replaced with the second IDT equivalently.

[0056] In some embodiments, when the capacitance of the first IDT and the second IDT are equivalent, the first IDT is used to replace the second IDT. When the antenna end receives multiple signals, if the first sub-IDT includes two first sub-IDTs, the node voltages of the two first sub-IDTs are 1 / 2 of the node voltage of the second IDT. Although the power intensity borne by the first IDT and the second IDT is the same, it can also be understood that the sum of the power intensity borne by the two sub-IDTs is the same as the power intensity of the second IDT. Assuming that the power intensity borne by the second IDT is P, the power intensity of the sub-IDT can be P / 2. At this time, assuming that the power of the third-order intermodulation signal generated by the second IDT is Q, since the third-order intermodulation signal is proportional to the cube of the power generated by the passive device, the third-order intermodulation signal generated by the first sub-IDT is 1 / 8 of the power of the third-order intermodulation signal generated by the second IDT, so the third-order intermodulation signal generated by the two first sub-IDTs is Q / 4.

[0057] In some embodiments, the number of reflection gates of the first IDT may be the same as the number of reflection gates of the second IDT.

[0058] In some embodiments, in a SAW filter, when the number of reflection gratings of the first IDT and the second IDT is the same, the first IDT and the second IDT can be considered to have the same reflection unit. Such a design can be used to ensure that the surface acoustic wave has consistency during propagation and reflection, thereby improving the performance and reliability of the SAW filter.

[0059] In some embodiments, the area of ​​the first IDT is larger than that of the second IDT. For example, when the amount of the forked fingers of the sub-IDT is greater than or equal to that of the second IDT, and the aperture length of the sub-IDT is greater than that of the second IDT, the area of ​​the first IDT can be considered to be larger than that of the second IDT. Alternatively, when the amount of the forked fingers of the sub-IDT is greater than that of the second IDT, and the aperture length of the sub-IDT is greater than that of the second IDT, the area of ​​the first IDT can also be considered to be larger than that of the second IDT.

[0060] In some embodiments, the IDT can transmit and receive surface acoustic waves through a series of periodically arranged metal strips. The metal strips can be understood as interdigitated strips, and the number of interdigits, the aperture of the interdigits, and the distance between adjacent interdigits will affect the resonant frequency of the IDT.

[0061] Exemplarily, the aperture area of ​​the IDT can be equal to the sum of the finger width of the IDT and the distance between adjacent fingers, multiplied by the finger length. When the number of fingers of the IDT is increased, or the aperture of the IDT is increased, or the width or length of a single finger in the IDT is increased, it can also be said that the aperture area of ​​the IDT is increased. At this time, the capacitance value contained in the newly generated IDT is also increased. When the capacitance of the IDT changes, the resonant frequency of the IDT will change, and when receiving the same input signal, the intensity received by the IDT will also change. For example, when the input signal remains unchanged, the aperture area of ​​the IDT doubles, then the power intensity received by the IDT can also be doubled.

[0062] For example, when the number of interdigits of the IDT is reduced, or the aperture of the IDT is reduced, or the width or length of a single interdigit in the IDT is reduced, that is, the aperture area of ​​the IDT is reduced, then the capacitance value of the newly generated IDT is also reduced.

[0063] In some embodiments, if the number of cross-digits of the sub-IDT is greater than or equal to the second IDT, or the aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT, the capacitance of the sub-IDT may be greater than or equal to the second IDT.

[0064] In some embodiments, the sub-IDT can be obtained by adjusting the number of cross-digits of the second IDT or adjusting the aperture length of the second IDT. In other words, the sub-IDT can also be obtained by adjusting the aperture area of ​​the second IDT, thereby obtaining the first IDT.

[0065] In some embodiments, when the capacitance of the first IDT is equivalent to that of the second IDT, multiple sub-IDTs in the first IDT can be obtained by increasing the aperture area of ​​the second IDT. For example, a new IDT can be obtained by adjusting the number of cross-indexes of the second IDT or adjusting the aperture length of the second IDT, and the new IDT can be a sub-IDT.

[0066] Figure 2A This is a possible structural diagram of the second IDT in the embodiment of the present application.

[0067] In some embodiments, Figure 2A The number of cross-indexes of the second IDT in the , is increased to generate a new IDT. Figure 2A The number of crossovers of the second IDT in the equation is doubled, giving Figure 2B Schematic diagram of the IDT structure.

[0068] In some embodiments, Figure 2A The aperture length of the second IDT in the embodiment is increased to generate a new IDT. Figure 2A The aperture length of the second IDT in is doubled, and we get Figure 2C Schematic diagram of the IDT structure.

[0069] The first IDT includes a plurality of sub-IDTs which may be Figure 2B , Figure 2C The newly generated IDT.

[0070] In some embodiments, the plurality of serially connected sub-IDTs may include a first sub-IDT.

[0071] In some embodiments, the aperture area of ​​the second IDT multiplied by the number of fork fingers of the second IDT multiplied by the first number can be equal to the aperture area of ​​the first sub-IDT, and the sum of the finger width of the second IDT and the distance between adjacent fingers of the second IDT multiplied by the finger length of the second IDT is equal to the aperture area of ​​the second IDT, wherein the first number is related to the number of sub-IDTs included in the first IDT.

[0072] Exemplarily, when the number of reflective gratings in the first IDT and the second IDT is the same, the second IDT can obtain a sub-IDT by increasing the area, so that the capacitance of the first IDT including the plurality of sub-IDTs is the same as that of the second IDT.

[0073] For example, the second IDT can be a primary IDT, and by increasing the area, a new IDT, that is, a sub-IDT, can be generated, which is called a secondary IDT. For example, the area of ​​the aperture region electrode finger of the primary IDT is equal to (length of the interdigital strip * width) * interdigital number * 2, and the new IDT aperture region area is obtained. These two new IDTs can be included in the first IDT. In this embodiment, there is no limitation on how the new IDT interdigital strip is designed, as long as the IDT aperture region area meets the requirements.

[0074] Optionally, if the equivalent capacitance of the two secondary IDTs included in the first IDT is different from the capacitance of the second IDT, it is necessary to continue to increase the area to make the first IDT equivalent to the second IDT. For example, based on the two secondary IDTs, any one of the secondary IDTs can be selected, and the area of ​​the electrode finger in the aperture area * the number of the cross fingers of the IDT * 3 / 2 can be used to obtain a new IDT. This new IDT can be a sub-IDT, called a three-level IDT.

[0075] Optionally, if the first IDT includes the above-mentioned primary IDT, secondary IDT or tertiary IDT, the equivalent capacitance is still different from the capacitance of the second IDT. For example, one of the primary IDT, secondary IDT or tertiary IDT can be selected, and the area of ​​the electrode finger in the aperture region*the number of fingers*4 / 3 is adopted.

[0076] Step S130: setting an output terminal in the filter, where the output terminal is used to output the signal filtered by the first IDT.

[0077] In some embodiments, the antenna end of the filter may receive multiple signals, the multiple signals may be filtered through the first IDT, and the filtered signals may be output through the output end of the filter.

[0078] In some embodiments, the output signal of the filter may include an intermodulation interference signal generated by multiple signals passing through the filter.

[0079] The present application proposes a method for manufacturing a filter, which can replace the second IDT with a first IDT having an area larger than that of the second IDT, so that the node voltage of the sub-IDT in the first IDT is reduced under the condition that the first IDT is equivalent to the second IDT, thereby reducing the passive intermodulation signal generated by the sub-IDT. And because the reduction of the intermodulation signal is nonlinear, the intermodulation signal of the first IDT is reduced, thereby improving the overall performance of the communication system.

[0080] As described above, passive intermodulation signals are generated in the process of filtering multiple signals received by the antenna end. Therefore, in the process of filtering multiple signals by the filter, the first IDT can be set at the antenna end close to the filter to reduce the passive intermodulation signals generated after the multiple signals enter, so as to reduce the influence of the passive intermodulation signals on the filter.

[0081] In some embodiments, the first IDT is electrically connected to the antenna terminal, and the first IDT includes a first series IDT electrically connected to the antenna terminal. The first IDT can filter multiple signals when the multiple signals enter the filter, thereby reducing the passive intermodulation signal generated when the signal enters the filter again, thereby reducing the passive intermodulation signal on the overall performance of the filter.

[0082] In some embodiments, if at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT may include at least one parallel IDT and the first series IDT.

[0083] When the first IDT connected to the antenna terminal is a parallel IDT, the parallel IDT may be a sub-IDT. Optionally, if the IDT connected to the antenna terminal is a plurality of parallel IDTs, the plurality of parallel IDTs may be sub-IDTs.

[0084] In some embodiments, a piezoelectric substrate may be provided in the filter, and a plurality of resonators may be provided on the piezoelectric substrate. Optionally, each resonator may include an IDT.

[0085] In some embodiments, the antenna end may be connected to the resonator, and the IDT area of ​​the resonator closest to the antenna end may be the largest among the multiple resonators in the filter. Optionally, the IDT of the resonator closest to the antenna end may be the first IDT.

[0086] Exemplarily, when the antenna end is connected to only one resonator, such as the antenna end is connected to resonator A, and resonator A is connected in series with resonator B, then at this time, the IDT area of ​​resonator A is larger than that of resonator B. The IDT of resonator A may be a first IDT.

[0087] Exemplarily, when the antenna end is connected to multiple resonators and the other ends of the multiple resonators are connected to one resonator, optionally, the IDTs of the multiple resonators form a parallel IDT and are connected in series with another resonator. Then the first IDT may include the parallel IDT and another resonator connected in series therewith. For example, the antenna end is connected to resonators A and B respectively, resonators A and B are connected in parallel, and resonators A and B are connected in series with resonator C respectively. Then the first IDT may include resonators A, B, and C. Optionally, the IDTs of multiple resonators form a parallel IDT and are connected in series with another resonator. Then the first IDT may be any one of the multiple parallel IDTs. For example, the antenna end may be connected to resonators A and B respectively, then resonators A and B are connected in parallel, and resonators A and B are connected in series with resonator C respectively. Optionally, resonators A and B may both be first IDTs, and the IDT areas of resonators A and B are both larger than the IDT area of ​​resonator C. In some embodiments, the IDT areas of resonators A and B may be the same size; in some embodiments, the IDT area of ​​resonator A may be larger than the IDT area of ​​resonator B, but the IDT area of ​​resonator B must be larger than the IDT area of ​​resonator C.

[0088] Based on the above discussion, it can be understood that the IDT area of ​​the resonator connected in series with the antenna terminal can be larger than the IDT area of ​​other resonators.

[0089] In some embodiments, when the module requirements of the communication system are different and signals belonging to different frequency ranges need to be filtered out, different filter circuits can be set in the filter to filter frequency signals belonging to different frequency ranges.

[0090] In some embodiments, a first IDT may be provided in each filter circuit to reduce the passive intermodulation signal generated by the filter circuit, thereby reducing the influence of the passive intermodulation signal on the overall performance of the filter.

[0091] In some embodiments, the filter may include at least one filter circuit. When the filter includes multiple filter circuits, the multiple filter circuits may be electrically connected in parallel. When the antenna end inputs multiple signals into multiple filter circuits, the multiple filter circuits are electrically connected to the antenna end. The multiple filter circuits may be used to filter the multiple signals to obtain different filter signals. These different filter signals may be frequency signals that different filter circuits need to output.

[0092] In some embodiments, each filtering circuit may include a first IDT electrically connected to the antenna terminal, and the first IDT may include a first series IDT electrically connected to the antenna terminal.

[0093] In some embodiments, if at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT may include at least one parallel IDT and the first series IDT.

[0094] In some embodiments, at least one sub-filtering circuit and at least one sub-isolating circuit may be provided in the filter.

[0095] Exemplarily, at least one sub-filter circuit may be the above-mentioned filter circuit, and at least one sub-filter circuit may be used to filter multiple signals received by the antenna end to obtain a first signal. Optionally, the first signal may be a frequency signal that the filter needs to output. Optionally, the first signal includes a frequency signal filtered out by at least one sub-filter circuit. Optionally, the first signal may be a frequency signal that the filter needs to output.

[0096] Exemplarily, at least one sub-isolation circuit can be electrically connected in parallel with at least one sub-filtering circuit, and at least one isolation circuit is connected to a load. Through at least one sub-isolation circuit, multiple signals can be filtered to obtain a second signal. Optionally, the second signal can be a frequency signal different from the frequency of the first signal among the multiple signals received by the antenna end. Optionally, the second signal can be a signal that is not required by the filter.

[0097] In some embodiments, the second signal isolated by at least one sub-isolation circuit may be absorbed by the load.

[0098] In an embodiment of the present application, by setting up at least one sub-isolation circuit, a second signal with a signal frequency different from the first signal among multiple signals received by the antenna end is filtered out and absorbed by the load, thereby reducing the signal reflection of the second signal to the front-end circuit and reducing the interference of the second signal to the first signal, thereby improving the overall performance of the communication system.

[0099] In some embodiments, when at least one sub-isolation circuit filters multiple received signals at the antenna end, the intermodulation signal generated by the passive device in at least one sub-isolation circuit may just fall within the range of the first signal, and the intermodulation signal will be output through at least one sub-filtering circuit, causing signal interference to at least one sub-filtering circuit, thereby affecting the communication system. Optionally, when at least one sub-isolation circuit includes a second IDT, a first IDT with a larger area can be used to replace the second IDT, and the first IDT is equivalent to the second IDT, so as to reduce the intermodulation signal generated on the sub-isolation circuit by increasing the area, thereby improving the overall performance of the system.

[0100] In some embodiments, a first IDT may be provided in both the at least one sub-filtering circuit and the at least one sub-isolating circuit, so as to reduce intermodulation signals generated by the at least one sub-filtering circuit and the at least one sub-isolating circuit.

[0101] Below Figure 3 , Figure 4A , Figure 4B The embodiments of the present application are described by taking the example.

[0102] Figure 3 It is a circuit diagram of a filter in an embodiment of the present application. Figure 4A yes Figure 3 A schematic diagram of a circuit layout distribution.

[0103] Figure 4A In the embodiment, A20 is arranged at a position close to the antenna end. A20 may be a second IDT. In some embodiments, when the number of reflective gratings of the first IDT and the second IDT is the same, the second IDT may obtain a sub-IDT by increasing the area, so that the capacitance of the first IDT including a plurality of sub-IDTs is the same as that of the second IDT. For example, Figure 4B B20 shown in FIG. 1 may be the first IDT equivalent to A20. After A20 is enlarged by 77%, B20 is obtained. Figure 5A As shown, the second IDT may be A20, and the first IDT may be B20.

[0104] Optionally, Figure 4A In the figure, A22 near the antenna end can be increased by 77% to obtain B22, as shown in Figure 5B , the second IDT may be A22 and the first IDT may be B22.

[0105] Optionally, Figure 4A In the figure, A24 near the antenna end can increase the area by 77% to obtain B24, as shown in Figure 5C , the second IDT may be A24 and the first IDT may be B24.

[0106] Optionally, Figure 4A In the figure, A25 near the antenna end can be increased by 77% to obtain B25, as shown in Figure 5D , the second IDT may be A25 and the first IDT may be B25.

[0107] Optionally, Figure 4A In the figure, the area of ​​A29 near the antenna end can be increased by 77% to obtain B29, as shown in Figure 5E , the second IDT may be A29 and the first IDT may be B29.

[0108] By setting the first IDT close to the antenna end, after receiving multiple signals at the antenna end of the filter, filtering can be performed through the first IDT to timely reduce the node voltage of the sub-IDT in the first IDT, thereby effectively reducing the strength of the intermodulation signal and improving the performance of the filter.

[0109] from Figure 3 It can be seen that Figure 3 In the embodiment, the first filter circuit group and the second filter circuit group are connected to the output end, therefore, the first filter circuit group and the second filter circuit group can be sub-filter circuits; the third filter circuit group and the fourth filter circuit group are connected to the load, therefore, the third filter circuit group and the fourth filter circuit group can be sub-isolation circuits.

[0110] like Figure 3 As shown, the first group of sub-filter circuits corresponds to the IDTs A11 to A19, so A11 can be the IDT closest to the antenna end in the first group of sub-filter circuits; the second group of sub-filter circuits corresponds to the IDTs A1 to A10, so A1 can be the IDT closest to the antenna end in the second group of sub-filter circuits; the first group of sub-isolation circuits corresponds to the IDTs A20 to A24, so A20 can be the IDT closest to the antenna end in the first group of sub-isolation circuits; the second group of sub-isolation circuits corresponds to the IDTs A25 to A29, so A25 can be the IDT closest to the antenna end in the second group of sub-isolation circuits.

[0111] In some embodiments, the frequency of the passive intermodulation signal generated by the first group of sub-isolation circuits and the second group of sub-isolation circuits during the second filtering process may just fall within the frequency range that the first group of sub-filter circuits and / or the second group of sub-filter circuits can pass, that is, within the frequency range of the first signal, thereby interfering with the communication signal of the first group of sub-filter circuits and / or the second group of sub-filter circuits. In some embodiments, the first IDT can be set in the first group of sub-isolation circuits and the second group of sub-isolation circuits to reduce the interference caused by the intermodulation signal generated by the first group of sub-isolation circuits and the second group of sub-isolation circuits to the first signal of the first group of filter circuits and the second group of filter circuits.

[0112] In some embodiments, the first IDT can be set at the position of A1, A11, A20, A25. By setting the first IDT at a position close to the antenna end in different filtering circuits, multiple signals can be input into at least one sub-filtering circuit and / or at least one sub-isolation circuit, and filtered through the first DIT to timely reduce the node voltage of the sub-IDT in the first IDT, thereby effectively reducing the strength of the intermodulation signal, thereby improving the performance of the filter.

[0113] For example, Figure 6The communication system schematic diagram shown is used to test the intermodulation interference signal of the SAW filter, and the strength of the intermodulation interference signal corresponding to the input signals of different frequencies can be obtained.

[0114] Figure 6 In the example, the input signals are F1 and F2. Figure 6 The DUT shown in FIG. 1 can be used to test the intermodulation interference signal of the communication system. The DUT can be a SAW filter, and the SAW filter can be used to filter out the frequency signal within the range of 1710-1760 MHz. For example, the layout of the DUT can be Figure 4A .

[0115] Figure 6 It includes steps S610 to S630.

[0116] Step S610, the input signal F1 is 1930MHz, the input signal F2 is 2150MHz, the input signals F1 and F2 first pass through the bridge, and the signals obtained after passing through the bridge can be filtered through a filter for filtering out the frequency range of 1930-2200MHz to obtain the input signals F1 and F2. The signals obtained after passing through the bridge can also be filtered through a filter for filtering out the frequency range of 1710-1760MHz to filter out the interference signals generated by F1 and F2 passing through the bridge.

[0117] And connect the filtered interference signal to the load.

[0118] Step S620: After step S610, it can be ensured that the input signals entering the antenna end of the device under test are only F1 and F2 signals. After the input signals F1 and F2 enter the device under test, the device under test can generate a third-order intermodulation signal PIM, where PIM=2*F1-F2=1710MHz. Since the device under test is a SAW filter that can be used to filter out frequency signals within the range of 1710-1760MHz, the output end of the device under test can output the third-order intermodulation signal PIM=1710MHz and the input signals F1 and F2.

[0119] In step S630, the third-order intermodulation signal PIM outputted in step S620 may enter a spectrum analyzer to detect the energy level of the intermodulation signal.

[0120] Table 1 can be obtained by adjusting the frequencies of the input signals F1 and F2 and performing steps S610 to S630 in sequence.

[0121] Table 1

[0122]

[0123]

[0124] Figure 7 yes Figure 6 The performance curve diagram of the DUT is shown in Table 1. Figure 7 It can be obtained that when the input signals F1 and F2 change but the signal strength remains unchanged, for example, when the signal strengths of F1 and F2 are both 14dBm sine waves, the worst result of the generated third-order intermodulation signal is -87dBm.

[0125] According to the manufacturing method of the embodiment of the present application, Figure 6 The IDT included in the filter of the device under test is equivalently replaced by the first IDT. Exemplarily, the layout of the device under test can be Figure 4B Alternative Figure 4A , Figure 4B The IDT near the antenna end is Figure 4A The IDT area at the same position in the image is increased. It can be understood that Figure 4A The IDT in can be the second IDT, Figure 4B The IDT with an increased area may be the first IDT. When the input signals F1 and F2 are the same, the following steps are performed in sequence: Figure 6 Steps S610 to S630 in , thereby obtaining Table 2.

[0126] Table 2

[0127]

[0128] It can be seen from Table 2 that when the input signals F1 and F2 change but the signal strength remains unchanged, such as when the signal strengths of F1 and F2 are both 14dBm sine waves, the worst result of the generated third-order intermodulation signal is -93dBm. Compared with Table 1, it can be seen that the use of the solution in the embodiment of the present application reduces the signal strength of the third-order intermodulation signal by 6dB. Therefore, the solution in the embodiment of the present application can reduce the strength of the intermodulation signal to improve the performance of the entire communication system.

[0129] In some embodiments, when the first IDT is equivalent to the second IDT, for example, the capacitance of the first IDT is equivalent to the capacitance of the second IDT, the number of sub-IDTs included in the first IDT is also related to the first indicator. The first indicator may include one or more of the following: power capacity of the filter; insertion loss of the filter; stopband suppression of the filter.

[0130] In some embodiments, the power capacity of a filter may refer to the maximum input power that the filter can withstand without being damaged.

[0131] In some embodiments, the insertion loss of the filter may describe the degree of attenuation of the signal power by the filter. The insertion loss of the filter may affect the power loss of the signal when passing through the filter.

[0132] In some embodiments, the stopband suppression of the filter refers to the filter's ability to attenuate signals within the stopband range, which is an important indicator for measuring the performance of the filter selection. The higher the stopband suppression, the stronger the filter's ability to suppress out-of-band interference signals.

[0133] In some embodiments, the power handling of the filter, the insertion loss of the filter, and the stop-band rejection of the filter are related to the overall power performance of the filter.

[0134] In some embodiments, the number of IDTs in the filter is related to the overall power performance of the filter. Exemplarily, when the filter meets the first indicator, the number of sub-IDTs in the first IDT, the number of cross-indexes of the sub-IDTs, or the length of the aperture can be further determined. For example, when the input power of the filter is 30w, the filter can work normally. Based on this premise, the content of the first IDT can be determined; optionally, when the input power of the filter is 31w, the filter can no longer work normally. Based on this premise, it is necessary to ensure that the filter can work normally before determining the content of the first IDT.

[0135] When the filter is under the power that can work normally, consider setting the first DIT to meet the index of testing the passive intermodulation signal. It is understandable that if the filter can no longer work normally, it is meaningless to consider the impact of the passive intermodulation signal on the communication system at this time.

[0136] The method embodiment of the present application is described in detail above. Based on the above content, the present application also proposes a filter. Figure 8 It should be understood that the description of the above method embodiment corresponds to the description of the filter, so the parts not described in detail can refer to the above method embodiment.

[0137] Figure 8 A filter 800 is provided in an embodiment of the present application, and the filter 800 may be a surface acoustic wave filter.

[0138] The filter 800 may include a piezoelectric substrate. In some embodiments, the piezoelectric substrate is a key substrate material in the filter and may affect the performance of the filter. For example, the piezoelectric effect of the piezoelectric substrate is crucial to the performance of the filter.

[0139] The filter 800 may include an antenna terminal, which may be disposed on the piezoelectric substrate and electrically connected to the antenna, and the antenna terminal may be used to receive a plurality of signals.

[0140] The filter 800 may include an output signal terminal, which may be disposed on a piezoelectric substrate. The signal terminal may be used to output a signal, and may also be understood as a signal that needs to be filtered out by the output filter 800 .

[0141] The filter 800 may include a plurality of resonators, which may include a first resonator and an Nth resonator, wherein the first resonator may be connected to the antenna terminal, and the Nth resonator may be connected to the output terminal. Each resonator may include an IDT. In some embodiments, among the plurality of resonators, the IDT area of ​​the resonator closest to the antenna terminal is the largest among all the resonators, such as the first resonator is the resonator closest to the antenna terminal, and the IDT area of ​​the first resonator is the largest among all the resonators.

[0142] by Figure 5A For example, Figure 5A It can be a schematic diagram of a circuit layout distribution of the filter 800.

[0143] exist Figure 5A In the example, B20 can be considered as the resonator closest to the antenna end. In some embodiments, B20 can be the resonator with the largest IDT area among all resonators in the filter 800. That is, the IDT area of ​​B20 is larger than the IDT areas of B1 to B29.

[0144] In some embodiments, the IDT of the resonator closest to the antenna end may be a first IDT, such as the first resonator, and the IDTs of other resonators may be second IDTs.

[0145] In some embodiments, the first IDT may be equivalent to the second IDT. For example, the first IDT may be equivalent to the second IDT in capacitance. For example, when the first IDT includes two IDTs with a capacitance of 2PF, it may be equivalent to an IDT with a capacitance of 1PF, and the IDT with a capacitance of 1PF may be the second IDT. In other words, the first IDT may be replaced with the second IDT in capacitance.

[0146] In some embodiments, the first IDT may include a plurality of sub-IDTs connected in series, and the number of reflection gratings of the first IDT may be the same as the number of reflection gratings of the second IDT. Exemplarily in the filter 800, when the number of reflection gratings of the first IDT and the second IDT is the same, it can be considered that the first IDT and the second IDT have the same reflection unit to ensure that the surface acoustic wave has consistency during propagation and reflection, thereby improving the performance and reliability of the SAW filter.

[0147] In some embodiments, the amount of the forked fingers of the sub-IDT may be greater than or equal to the second IDT, and / or the aperture length of the sub-IDT may be greater than or equal to the aperture length of the second IDT. Exemplarily, when the amount of the forked fingers of the sub-IDT is greater than or equal to the second IDT and the aperture length of the sub-IDT is greater than the aperture length of the second IDT, it can be considered that the area of ​​the first IDT is greater than the second IDT. Or, when the amount of the forked fingers of the sub-IDT is greater than the second IDT and the aperture length of the sub-IDT is greater than the aperture length of the second IDT, it can also be considered that the area of ​​the first IDT is greater than the second IDT.

[0148] In some embodiments, the filter includes multiple second IDTs, and the second IDT closest to the antenna end can be replaced by the first IDT to generate a new filter. The original filter can be called the first filter, and the new filter can be called the second filter. The area of ​​the first IDT is larger than the area of ​​the second IDT, and the first IDT is equivalent to the second IDT. Exemplarily, the first IDT can include multiple sub-IDTs connected in series, and the capacitance of the first IDT is equivalent to that of the second IDT. Exemplarily, the number of reflection gratings of the first IDT can be the same as the number of reflection gratings of the second IDT, and the number of cross-indexes of the sub-IDT can be greater than or equal to the second IDT, and / or the aperture length of the sub-IDT can be greater than or equal to the aperture length of the second IDT.

[0149] In some embodiments, when the capacitance of the first IDT is equivalent to that of the second IDT, multiple sub-IDTs in the first IDT can be obtained by increasing the aperture area of ​​the second IDT. For example, a new IDT can be obtained by adjusting the number of cross-indexes of the second IDT or adjusting the aperture length of the second IDT, and the new IDT can be a sub-IDT.

[0150] In some embodiments, the plurality of serially connected sub-IDTs may include a first sub-IDT.

[0151] In some embodiments, the aperture area of ​​the second IDT multiplied by the number of fork fingers of the second IDT multiplied by the first number can be equal to the aperture area of ​​the first sub-IDT, and the sum of the finger width of the second IDT and the distance between adjacent fingers of the second IDT multiplied by the finger length of the second IDT is equal to the aperture area of ​​the second IDT, wherein the first number is related to the number of sub-IDTs included in the first IDT.

[0152] In some embodiments, when the first filter and the second filter described above are used to filter the same signal, since the first IDT is equivalent to the second IDT, the node voltage of each sub-IDT in the first IDT is reduced relative to the node voltage of the second IDT, thereby reducing the passive intermodulation signal generated by each sub-IDT. Since the reduction of the passive intermodulation signal is nonlinear, the total intermodulation signal generated by the first IDT in the second filter is lower than the intermodulation signal generated by the second IDT in the first filter. It can be understood that when the first IDT is used to replace the second filter generated by the second IDT closest to the antenna end in the first filter, the intermodulation signal generated by the second filter is lower than the intermodulation signal generated by the first filter under the premise that the input signal remains unchanged, thereby improving the overall performance of the communication system.

[0153] In some embodiments, the filter may include at least one first filter circuit, or at least one filter circuit and at least one isolation circuit. The first filter circuit and the first isolation circuit each include a plurality of resonators connected in series and a plurality of resonators connected in parallel, one end of the at least one first filter circuit is connected to the antenna end, and the other end is connected to the output signal end, and one end of the at least one first isolation circuit is connected to the antenna end, and the other end is connected to the load.

[0154] like Figure 3 The filter shown may include two first filter circuits and two first isolation circuits. The two first filter circuits respectively include a circuit composed of IDTs A11 to A19 and a circuit composed of IDTs A1 to A10, and the two first filter circuits are connected to the output end. The two first isolation circuits respectively include a circuit composed of IDTs A20 to A24 and a circuit composed of IDTs A25 to A29, and the two first isolation circuits are connected to the load.

[0155] In some embodiments, the first IDT is the first series IDT electrically connected to the antenna end, exemplarily, as Figure 3 As shown, the first IDT can be A11, A1, A20, A25. For example, taking a circuit composed of IDTs A1 to A10 as an example, if A1 is removed, A3 and A2 are both connected to the antenna end, then A2 and A3 are connected in parallel, and both A2 and A3 can be the first IDT.

[0156] In some embodiments, if at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT includes at least one parallel IDT and the first series IDT.

[0157] In some embodiments, the filter may include at least one first filter circuit, in which a first IDT is disposed. Exemplarily, the first IDT may be disposed in the at least one filter circuit, at a position closest to the antenna end.

[0158] In some embodiments, the filter may include at least one first filtering circuit and at least one first isolation circuit. For example, the first IDT may be disposed in at least one first isolation circuit, or the first IDT may be disposed in at least one first filtering circuit and at least one first isolation circuit at the same time.

[0159] To achieve the above object, the present invention further provides a communication device, the communication device comprising the filter described above. Since the communication device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0160] In addition, an embodiment of the present application also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a computer, the operations in the filter manufacturing method provided in the above embodiment are implemented. The specific steps will not be repeated here.

[0161] It should be understood that the terms "system" and "network" in this application can be used interchangeably. In addition, the terms used in this application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. The terms "first", "second", "third" and "fourth" in the specification and claims of this application and the accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions.

[0162] In the embodiments of the present application, a "field" may also be referred to as a "field", a "subfield" or a "subfield". A field may occupy one or more bytes (byte / octet), or a field may occupy one or more bits (bit).

[0163] In the embodiments of the present application, the "indication" mentioned can be a direct indication, an indirect indication, or an indication of an association relationship. For example, A indicates B, which can mean that A directly indicates B, for example, B can be obtained through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can be obtained through C; it can also mean that there is an association relationship between A and B.

[0164] In the embodiment of the present application, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0165] In the embodiments of the present application, the term "corresponding" may indicate that there is a direct or indirect correspondence between the two, or an association relationship between the two, or a relationship of indication and being indicated, configuration and being configured, etc.

[0166] In the embodiments of the present application, "pre-definition" or "pre-configuration" can be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in the device, and the present application does not limit the specific implementation method. For example, pre-definition can refer to what is defined in the protocol.

[0167] In the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0168] In the embodiments of the present application, the term "include" may refer to direct inclusion or indirect inclusion. Optionally, the term "include" mentioned in the embodiments of the present application may be replaced with "indicate" or "used to determine". For example, "A includes B" may be replaced with "A indicates B" or "A is used to determine B".

[0169] In various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0170] In the embodiments of the present application, the "protocol" may refer to a standard protocol in the communication field, for example, it may include a WiFi protocol and related protocols used in future WiFi communication systems, and the present application does not limit this.

[0171] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0172] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0173] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0174] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that can be read by a computer or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0175] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for manufacturing a filter, characterized in that: The filter is a surface acoustic wave filter, comprising: An antenna terminal is arranged in the filter, and the antenna terminal is used to receive multiple signals; A plurality of second IDTs are arranged in the filter, at least one of the second IDTs is replaced by a first IDT in the filter, an area of ​​the first IDT is larger than an area of ​​the second IDT, and the first IDT is equivalent to the second IDT, The first IDT includes a plurality of sub-IDTs connected in series, the number of reflection gratings of the first IDT is the same as the number of reflection gratings of the second IDT, the number of fork indexes of the sub-IDT is greater than or equal to the number of fork indexes of the second IDT, and / or the aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT; An output terminal is provided in the filter, and the output terminal is used to output the signal filtered by the first IDT.

2. The manufacturing method according to claim 1, characterized in that: The first IDT is electrically connected to the antenna end, The first IDT includes a first series IDT electrically connected to the antenna terminal, or, If at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT includes the at least one parallel IDT and the first series IDT.

3. The manufacturing method according to claim 1 or 2, characterized in that: The filter includes at least one filter circuit. When the filter includes a plurality of filter circuits, the plurality of filter circuits are electrically connected in parallel. The antenna end is used to input the multiple signals into the at least one filter circuit, The at least one filter circuit is electrically connected to the antenna end, and the at least one filter circuit is used to filter the multiple signals to obtain a filter signal, and the filter signal is a frequency signal that the at least one filter circuit needs to output. The output end is used to output the filtered signal. The at least one filtering circuit includes the first IDT.

4. The manufacturing method according to claim 1 or 2, characterized in that: include: At least one sub-filter circuit and at least one sub-isolation circuit are arranged in the filter, and the at least one sub-filter circuit and the one sub-isolation circuit are connected in parallel. The at least one sub-filter circuit is electrically connected to the output end, and the at least one sub-filter circuit is used to filter the multiple signals to obtain a first signal. The at least one sub-isolation circuit is electrically connected to the load, and the at least one sub-isolation circuit is used to filter the multiple signals to obtain a second signal. Wherein, the first signal is the frequency signal that the filter needs to output, The second signal is a frequency signal of the plurality of signals received by the antenna end that is different from the frequency of the first signal. The first IDT is disposed in the at least one sub-isolation circuit, or the first IDT is disposed in the at least one sub-filtering circuit and at least one sub-isolation circuit.

5. The manufacturing method according to claim 1, characterized in that: The plurality of serially connected sub-IDTs include a first sub-IDT, The aperture area of ​​the second IDT multiplied by the number of cross-digits of the second IDT multiplied by the first number equals the aperture area of ​​the first sub-IDT. The sum of the interdigital width of the second IDT and the distance between adjacent interdigits of the second IDT multiplied by the interdigital length of the second IDT is equal to the aperture area of ​​the second IDT. The first number is related to the number of sub-IDTs included in the first IDT.

6. The manufacturing method according to claim 1, characterized in that: The first IDT and the second IDT are equivalent in that the capacitance of the first IDT and the second IDT are equivalent, and the number of sub-IDTs included in the first IDT is related to a first indicator, and the first indicator includes one or more of the following: The power capacity of the filter; Insertion loss of the filter; The stopband rejection of the filter.

7. A filter, characterized in that: The filter is a surface acoustic wave filter, and the filter comprises: Piezoelectric substrate; An antenna end, disposed on the piezoelectric substrate and electrically connected to the antenna, the antenna end being used to receive multiple signals; An output signal terminal is arranged on the piezoelectric substrate, and the signal terminal is used to output a signal; A plurality of resonators are disposed on the piezoelectric substrate, each of the resonators comprising an IDT, in, Among the plurality of resonators, the IDT area of ​​the resonator closest to the antenna end is the largest among all the IDT areas of the resonators.

8. The filter according to claim 7, characterized in that The IDT of the resonator closest to the antenna end is the first IDT, and the IDTs of the other resonators are the second IDTs. The first IDT and the second IDT are equivalent. The first IDT includes multiple sub-IDTs connected in series. The number of reflection gratings of the first IDT is the same as the number of reflection gratings of the second IDT. The number of cross-indexes of the sub-IDT is greater than or equal to the second IDT, and / or the aperture length of the sub-IDT is greater than or equal to the aperture length of the second IDT.

9. The filter according to claim 8, characterized in that The filter includes at least one first filtering circuit, or at least one first filtering circuit and at least one first isolation circuit; The first filtering circuit and the first isolating circuit each include a plurality of the resonators connected in series and a plurality of the resonators connected in parallel, one end of the at least one first filtering circuit is connected to the antenna end, and the other end is connected to the output signal end, and one end of the at least one first isolating circuit is connected to the antenna end, and the other end is connected to the load; The first IDT is the first series IDT electrically connected to the antenna end, or, If at least one parallel IDT is included between the antenna end and the first series IDT, the first IDT includes the at least one parallel IDT and the first series IDT.

10. The filter according to claim 9, characterized in that When the filter includes the at least one first filter circuit, the first IDT is arranged on the at least one first filter circuit; When the filter includes the at least one first filtering circuit and the at least one first isolating circuit, the first IDT is disposed on the at least one first isolating circuit, or the first IDT is disposed on the at least one first filtering circuit and the at least one first isolating circuit.

11. The filter according to claim 8, characterized in that The plurality of serially connected sub-IDTs include a first sub-IDT, The aperture area of ​​the second IDT multiplied by the number of cross-digits of the second IDT multiplied by the first number equals the aperture area of ​​the first sub-IDT. The sum of the interdigital width of the second IDT and the distance between adjacent interdigits of the second IDT multiplied by the interdigital length of the second IDT is equal to the aperture area of ​​the second IDT. The first number is related to the number of sub-IDTs included in the first IDT.

12. A filter, characterized in that: The invention comprises a filter manufactured by the manufacturing method according to any one of claims 1 to 6.

13. A communication device, characterized in that: A filter comprising the filter according to any one of claims 7 to 12.

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