Filter and multiplexer comprising the same

Abstract

The present disclosure provides a filter and a multiplexer including the same. The filter according to the present disclosure includes a plurality of series resonance units connected in series between an input node and an output node of the filter and having a first resonance frequency, a first parallel resonance unit connected in parallel between a connection node and a ground node and having a second resonance frequency less than the first resonance frequency, the connection node being a node at an input end and / or an output end of the series resonance units, and a second parallel resonance unit connected in parallel between the connection node and the ground node and including first and second resonance sub-units connected in series, the first resonance sub-unit having a resonance frequency greater than or equal to the first resonance frequency, and the second resonance sub-unit having a resonance frequency greater than or equal to the second resonance frequency and less than the first resonance frequency. The filter and the multiplexer including the same according to the present disclosure can improve a roll-off characteristic on both sides of a passband of the filter and improve a power capacity of the filter.

Description

Technical Field

[0001] This disclosure relates to the field of electronic circuit technology, and in particular, to filters and multiplexers including such filters. Background Technology

[0002] With the development of wireless communication applications, people have increasingly higher requirements for data transmission rates. Corresponding to these higher data transmission rates is the high utilization rate of spectrum resources and the increasing complexity of the spectrum. The increasing complexity of communication protocols places stringent demands on various performance aspects of radio frequency (RF) systems. In the RF front-end module, RF filters and multiplexers play a crucial role, filtering out out-of-band interference and noise to meet the signal-to-noise ratio requirements of the RF system and communication protocols. With the increasing commercialization of 5G, the demand for multiplexers such as B1, B2, B3, B5, B7, and B8 is also growing significantly.

[0003] Currently, filters and multiplexers based on thin-film bulk acoustic resonators (FBARs) are increasingly widely used due to their advantages such as low insertion loss, steep roll-off characteristics, high selectivity, high power capacity, and strong electrostatic discharge (ESD) resistance.

[0004] However, the rapid development of wireless communication technology has led to increasingly scarce frequency resources, with frequency bands allocated to different signals becoming closer and closer. This has resulted in problems such as mutual interference between signals and system instability, which necessitates filters with better out-of-band attenuation performance to meet the requirements of information transmission.

[0005] Therefore, further improvements are needed to the roll-off characteristics of existing filters. The roll-off characteristic describes the width of the transition region between frequencies on either side of the filter's passband. A smaller roll-off region, i.e., a sharper frequency response curve, indicates a better roll-off characteristic and a filter performance closer to design requirements.

[0006] Therefore, there is still a need in the existing technology for a filter that can improve roll-off characteristics and a multiplexer constructed using that filter. Summary of the Invention

[0007] A brief overview of this disclosure is given below to provide a basic understanding of certain aspects thereof. However, it should be understood that this overview is not an exhaustive summary of this disclosure, nor is it intended to identify key or essential parts of this disclosure, nor is it intended to limit the scope of this disclosure. The purpose of this overview is merely to present some inventive concepts of this disclosure in a simplified form as a prelude to the more detailed description that follows.

[0008] The purpose of this disclosure is to provide a filter that can increase the number of out-of-band transmission zeros in the frequency response curve to enhance out-of-band attenuation, and a multiplexer constructed using the filter.

[0009] According to one aspect of this disclosure, a filter is provided, comprising: a plurality of series resonant units connected in series between an input node and an output node of the filter, the plurality of series resonant units having a first resonant frequency; a first parallel resonant unit connected in parallel between a connection node and a ground node, the connection node being a node at the input and / or output end of the series resonant units, the first parallel resonant unit having a second resonant frequency less than the first resonant frequency; and a second parallel resonant unit connected in parallel between the connection node and the ground node, and comprising a first resonant sub-unit and a second resonant sub-unit connected in series, the resonant frequency of the first resonant sub-unit being greater than or equal to the first resonant frequency, and the resonant frequency of the second resonant sub-unit being greater than or equal to the second resonant frequency and less than the first resonant frequency.

[0010] According to embodiments of this disclosure, the filter further includes: at least one third parallel resonant unit connected in parallel between the connection node and the ground node, and the resonant frequency of the third parallel resonant unit is greater than or equal to the second resonant frequency.

[0011] According to embodiments of this disclosure, the third parallel resonant unit is connected in parallel with the first parallel resonant unit, or at least one of the first parallel resonant units is replaced by the third parallel resonant unit.

[0012] According to embodiments of this disclosure, the second parallel resonant unit and the third parallel resonant unit generate transmission zeros.

[0013] According to embodiments of this disclosure, each of the plurality of series resonant units, the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit is composed of an acoustic resonator.

[0014] According to embodiments of this disclosure, the first parallel resonant unit and / or the third parallel resonant unit include an acoustic resonator or an acoustic resonator and an inductor connected in series between a connection node and a ground node.

[0015] According to embodiments of this disclosure, the first resonator unit and / or the second resonator unit includes an acoustic resonator or a series circuit of an acoustic resonator and an inductor.

[0016] According to embodiments of this disclosure, the acoustic resonator is a surface acoustic wave resonator, a thin-film bulk acoustic wave resonator, a solid-state assembly acoustic wave resonator, or a Lamb wave resonator.

[0017] According to embodiments of this disclosure, both the first resonator unit and the second resonator unit are composed of acoustic resonators, and the acoustic resonators constituting the first resonator unit and the second resonator unit have the same area.

[0018] According to embodiments of this disclosure, at least one of the plurality of series resonant units, the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit is composed of lumped elements including capacitors and inductors.

[0019] According to embodiments of this disclosure, any two of the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit are connected to the same connection node.

[0020] According to another aspect of this disclosure, a multiplexer is provided, which includes the filter according to the above aspects of this disclosure.

[0021] According to the filter disclosed herein and the multiplexer including the filter, it is possible to improve the roll-off characteristics on both sides of the passband of the filter, reduce the power dissipation density, and increase the power capacity of the filter. Attached Figure Description

[0022] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and form a part of this specification. The drawings illustrate embodiments of this disclosure and, together with the following description, serve to illustrate the principles of this disclosure.

[0023] Figure 1 An equivalent circuit diagram of a filter according to the prior art is shown.

[0024] Figure 2 An equivalent circuit diagram of a filter according to a first embodiment of the present disclosure is shown.

[0025] Figure 3 It shows Figure 2 The diagram shows an example of the frequency response curve of the filter.

[0026] Figures 4A to 4F An equivalent circuit diagram of an example filter according to a second embodiment of the present disclosure is shown.

[0027] Figure 5 It shows Figure 4A The diagram shows the zeros on the left side of the passband of the filter.

[0028] Figures 6A to 6F An equivalent circuit diagram of an example filter according to a third embodiment of the present disclosure is shown.

[0029] Figure 7 It shows Figure 6A The diagram shows the zeros on the right side of the passband of the filter.

[0030] Figures 8A to 8E An equivalent circuit diagram of an example filter according to a fourth embodiment of the present disclosure is shown. Detailed Implementation

[0031] In this specification, it will also be understood that when an element is referred to relative to other elements, such as “on,” “connected to,” or “coupled to” other elements, that element may be directly disposed on, directly connected to, or directly coupled to that element, or there may be an intervening third element. Conversely, when an element is referred to in this specification relative to other elements, such as “directly” on, directly connected to, or directly coupled to other elements, there is no intervening element between them.

[0032] The present disclosure will now be described more fully below with reference to the accompanying drawings, in which various embodiments are illustrated. However, the present disclosure may be implemented in many different ways and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the disclosure will be exhaustive and complete, and will fully convey the scope of the disclosure to those skilled in the art. The same reference numerals denote the same elements throughout the drawings. Furthermore, in the drawings, the thickness, proportions, and dimensions of components are enlarged for clarity.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the terms “a,” “an,” “the,” and “at least one” as used herein are not intended to limit the quantity but are intended to include both singular and plural forms. For example, unless the context clearly indicates otherwise, “an element” has the same meaning as “at least one element.” “At least one” should not be construed as limited to the quantity “a.” “Or” means “and / or.” The term “and / or” includes any and all combinations of at least one of the associated listed items.

[0034] Unless otherwise specified, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries shall be interpreted as having the same meaning as in the relevant technical context, and shall not be construed as having a formal meaning in an idealized or overly formal sense unless expressly defined in the specification.

[0035] The meaning of “includes” or “contains” is to specify a nature, quantity, step, operation, element, component, or combination thereof, but does not exclude other natures, quantities, steps, operations, elements, components, or combinations thereof.

[0036] This document describes embodiments with reference to cross-sectional views as idealized implementations. Thus, variations in shape relative to the illustrations are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but should include deviations in shape due to, for example, manufacturing processes. For example, regions shown or described as flat may typically have rough and / or non-linear characteristics. Furthermore, acute angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show precise shapes of the regions and are not intended to limit the scope of the claims.

[0037] In the following description, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0038] Figure 1 An equivalent circuit diagram of a filter 100 according to the prior art is shown.

[0039] like Figure 1 As shown, filter 100 is, for example, a 3.5-step trapezoidal filter, which consists of three series resonant units S11 to S13 and four parallel resonant units P11 to P14.

[0040] like Figure 1 As shown, series resonant units S11 to S13 are connected in series between the input node IN and the output node OUT of the filter 100. Furthermore, an input impedance matching unit (not shown) can be connected in series and / or parallel between the input node IN and the series resonant unit S11, and an output impedance matching unit (not shown) can be connected in series and / or parallel between the series resonant unit S13 and the output node OUT. The input impedance matching unit and the output impedance matching unit can be composed of impedance matching elements such as inductors and capacitors.

[0041] In addition, such as Figure 1 As shown, the parallel resonant units P11 to P14 are connected in parallel between the connection nodes N11 to N14 and the ground node GND. The connection nodes N11 to N14 are the nodes at the input and / or output terminals of the series resonant units S11 to S13.

[0042] The series resonant units S11 to S13 and the parallel resonant units P11 to P14 are collectively referred to herein as "resonant units". Those skilled in the art will recognize that the "resonant unit" referred to herein can consist of a single resonator, or it can consist of a resonator connected in series with an inductor and / or a capacitor in parallel. For example, each of the parallel resonant units P11 to P14 can consist of a resonator and an inductor connected in series between the connection node and the ground node.

[0043] The series resonant units S11 to S13 typically have the same or very close resonant frequencies, and the parallel resonant units P11 to P14 typically also have the same or very close resonant frequencies.

[0044] The resonant frequency of a resonant element when its impedance reaches its minimum value is called the series resonant frequency, and the resonant frequency when its impedance reaches its maximum value is called the parallel resonant frequency. The series resonant frequency of a resonant element is less than its parallel resonant frequency. Within the range between the series and parallel resonant frequencies, the resonant element exhibits inductive impedance and can be considered an inductor, with a quality factor much greater than that of a typical inductor. Furthermore, within the range below the series resonant frequency or above the parallel resonant frequency, the resonant element exhibits capacitive impedance and can be considered a capacitor, with a quality factor much greater than that of a typical capacitor.

[0045] Since the filter 100 according to the prior art is well known to those skilled in the art, its details will not be described in more detail here.

[0046] The inventive concept of this disclosure lies in... Figure 1 The circuit structure of the filter 100 shown in the prior art has been improved to enhance the roll-off characteristics on both sides of the filter's passband. Furthermore, those skilled in the art will recognize that although embodiments of this disclosure are described herein using a trapezoidal filter as an example, this disclosure is not limited thereto. Based on the teachings of this disclosure, those skilled in the art can readily conceive of applying the inventive concepts of this disclosure to other filter circuit topologies besides trapezoidal filters.

[0047] Figure 2 An equivalent circuit diagram of a filter 200 according to a first embodiment of the present disclosure is shown.

[0048] and Figure 1 The filter shown is similar to filter 100. Figure 2 The filter 200 shown includes series resonant units S21 to S23, which are connected in series between the input node IN and the output node OUT of the filter 200; and parallel resonant units P21 to P24, which are connected in parallel between the connection nodes N21 to N24 and the ground node GND. The connection nodes N21 to N24 are nodes at the input and / or output terminals of the series resonant units S21 to S23.

[0049] According to embodiments of this disclosure, the series resonant units S21 to S23 may have the same resonant frequency f1, referred to herein as the "first resonant frequency". Having the same resonant frequency for each series resonant unit S21 to S23 can reduce errors caused by manufacturing processes.

[0050] Unlike Figure 1The filter 100 shown, according to an embodiment of the present disclosure, includes at least one of the parallel resonant units P21 to P24, for example... Figure 2 The parallel resonant unit P24 shown includes a first resonant element P241 and a second resonant element P242 connected in series. The parallel resonant unit P24 is a specific example of a second parallel resonant unit.

[0051] According to embodiments of this disclosure, the parallel resonant units P21 to P23, excluding parallel resonant unit P24, can have the same resonant frequency f2, referred to herein as the "second resonant frequency". Having the same resonant frequency among the parallel resonant units P21 to P24 can reduce errors caused by manufacturing processes.

[0052] According to embodiments of this disclosure, the second resonant frequency f2 is less than the first resonant frequency f1. Parallel resonant units P21 to P23 are specific examples of the first parallel resonant unit.

[0053] According to embodiments of this disclosure, the resonant frequency of the first resonant subunit P241 can be greater than or equal to the first resonant frequency, while the resonant frequency of the second resonant subunit P242 can be greater than or equal to the second resonant frequency and less than the first resonant frequency. Figure 2 The diagram shows that the resonant frequency of the first resonant element P241 is equal to the first resonant frequency f1, and the resonant frequency of the second resonant element P242 is equal to the second resonant frequency f2.

[0054] According to embodiments of this disclosure, each of the series resonant units S21 to S23 and the parallel resonant units P21 to P24 can be composed of an acoustic resonator.

[0055] Furthermore, according to embodiments of this disclosure, each of the first resonator unit P241 and the second resonator unit P242 may be composed of an acoustic resonator, and the acoustic resonators constituting the first resonator unit P241 and the second resonator unit P242 have the same area, which can reduce errors caused by manufacturing processes.

[0056] According to embodiments of this disclosure, the acoustic resonators constituting the above-described resonant units and / or resonator subunits may be, for example, surface acoustic wave resonators, thin-film bulk acoustic wave resonators, solid-state assembly acoustic wave resonators, or Lamb wave resonators.

[0057] Furthermore, according to embodiments of this disclosure, at least one of the series resonant units S21 to S23 and the parallel resonant units P21 to P24 may also be composed of lumped elements including capacitors and inductors.

[0058] Those skilled in the art should recognize that, although this article is based on Figure 2 The 3.5th order trapezoidal filter 200 shown illustrates an embodiment of this disclosure, but the disclosure is not limited thereto. Those skilled in the art will recognize that the inventive concept of this disclosure can be applied to trapezoidal filters of any order.

[0059] Furthermore, although this document describes embodiments of the present disclosure based on the example of a second parallel resonant unit P24 comprising a first resonant subunit P241 and a second resonant subunit P242 connected in series, the present disclosure is not limited thereto. Those skilled in the art will recognize that any one or more of the parallel resonant units P21 to P24 can be a second parallel resonant unit composed of a first resonant subunit and a second resonant subunit connected in series.

[0060] According to embodiments of this disclosure, the parallel resonant unit P24, composed of the first resonant unit P241 and the second resonant unit P242 connected in series, can generate a transmission zero in the frequency response curve of the filter 200.

[0061] In signal processing systems, transmission zeros, or simply zeros, have a decisive influence on the in-band loss and out-of-band attenuation of filters.

[0062] In filter 200, the number and location of transmission zeros are jointly determined by the series resonant frequency and the parallel resonant frequency of each resonant unit. Therefore, by adjusting parameters such as the area and thickness of the acoustic resonators constituting each resonant unit, the series resonant frequency and the parallel resonant frequency of each resonant unit can be adjusted, thereby adjusting the number and location of transmission zeros in the filter.

[0063] Figure 3 It shows Figure 2 The diagram shows an example of the frequency response curve of filter 200. (In the context of plotting...) Figure 3 In the filter 200 with frequency response curves, the resonant frequency of the first resonant subunit P241 of the parallel resonant unit P24 is equal to the first resonant frequency f1, and the resonant frequency of the second resonant subunit P242 of the parallel resonant unit P24 is equal to the second resonant frequency f2.

[0064] Figure 3 Curves 1-2 and 1-1 in the figure show the zero points generated when the parallel resonant unit P24 has only the first resonant subunit P241 and the parallel resonant unit P24 has only the second resonant subunit P242 (at this time, the parallel resonant unit P22 is equivalent to the parallel resonant units P21 to P23).

[0065] Figure 3Curve 2 in the diagram illustrates the zero point generated when the parallel resonant unit P24 has a first resonant subunit P241 and a second resonant subunit P242 connected in series. At this time, from... Figure 3 As can be seen, the zero point shifts to the right (high frequency). This is because the resonant frequency of the second resonant unit P242 (i.e., the second resonant frequency) is lower than the resonant frequency of the first resonant unit P241 (i.e., the first resonant frequency), making the first resonant unit P241 capacitive. Therefore, the resonant frequency (zero point) of the second resonant unit P242 shifts to the right (high frequency). Similarly, the resonant frequency (first resonant frequency) of the first resonant unit P241 is higher than the resonant frequency (second resonant frequency) of the second resonant unit P242, making the second resonant unit P242 capacitive. Therefore, the resonant frequency (zero point) of the first resonant unit P241 shifts to the right (high frequency). The two zero points shown in curve 2 are related to the effective resonant area ratio, resonant frequency difference, and absolute value of the resonant frequency of the acoustic resonators constituting the first and second resonant units P241 and P242.

[0066] Figure 3 Curve 3 shows the frequency response curve of the filter 200 according to the first embodiment of this disclosure. From Figure 3 As can be seen from curve 3, the roll-off characteristics on both sides of the passband of filter 200 are enhanced.

[0067] Compared to the filter 100 according to the prior art, the filter 200 according to the first embodiment of the present disclosure can generate two stopbands by setting two series-connected resonant units in a parallel resonant unit. One stopband falls into the left edge of the passband of the filter, and the other stopband falls into the right edge of the passband of the filter, thereby jointly controlling the edge roll-off on both sides.

[0068] Figures 4A to 4F An equivalent circuit diagram of an example filter 400 according to a second embodiment of the present disclosure is shown. For the sake of brevity, Figures 4A to 4F The filter 400 shown is with Figure 2 The same components of the filter 200 shown are indicated by the same reference numerals, and detailed descriptions of these same components will be omitted. The following will only describe... Figures 4A to 4F The filter 400 shown is Figure 2 The differences of the filter 200 shown will be explained in detail.

[0069] like Figure 4AAs shown, according to the second embodiment of the present disclosure, the resonance frequency f3 of the parallel resonance unit P23 included in the filter 400 may be greater than the second resonance frequency and less than the first resonance frequency, that is, f2 < f3 < f1, which may be referred to as the "third resonance frequency" herein. The parallel resonance unit P23 is a specific example of the third parallel resonance unit.

[0070] According to an embodiment of the present disclosure, the parallel resonance unit P23 may generate a transmission zero. Figure 5 Shows Figure 4A A schematic diagram of the zero point on the left side of the passband of the filter 400 shown. Figure 5 The meanings and values of the abscissa and ordinate in Figure 3 are similar, so they are not shown in Figure 5 . As Figure 5 shown, point A represents the zero point generated by the parallel resonance unit P23 on the left side (low-frequency side) of the passband of the filter 400, and point B represents the zero point generated by the parallel resonance unit P24 on the left side of the passband of the filter 400.

[0071] According to the second embodiment of the present disclosure, by adjusting the resonance frequency of the parallel resonance unit P23, while ensuring a high roll-off on both sides of the passband of the filter 400, the resonance frequency of the parallel resonance unit P24 can be shifted to a lower frequency, increasing the adjustment space for power capacity regulation, and a lower dissipation power density can be obtained, thereby improving the power capacity of the filter.

[0072] Although the filter 400 according to the second embodiment of the present disclosure is described herein in combination with Figure 4A the circuit structure shown, the present disclosure is not limited thereto. Figures 4B to 4F Shows the circuit structure of the filter 400 according to the second embodiment of the present disclosure as another example.

[0073] As Figure 4B shown, the filter 400 may include two second parallel resonance units, that is, the parallel resonance units P21 and P24, where the parallel resonance unit P21 includes a first resonance sub-unit P211 and a second resonance sub-unit P212 connected in series. In Figure 4B , similar to the parallel resonance unit P24, it is shown that the resonance frequency of the first resonance sub-unit P211 of the parallel resonance unit P21 is equal to the first resonance frequency f1, and the resonance frequency of the second resonance sub-unit P212 of the parallel resonance unit P21 is equal to the second resonance frequency f2.

[0074] As Figure 4CAs shown, the filter 400 may include two second parallel resonant units, namely parallel resonant units P21 and P24. The second resonant subunit P242 of the parallel resonant unit P24 has a third resonant frequency f3. Figure 4B compared to, Figure 4C The difference lies in that the second resonant subunit P242 of the parallel resonant unit P24 has a third resonant frequency f3, and the parallel resonant unit P23 has a second resonant frequency f2, where f2 <f3<f1。

[0075] like Figures 4D to 4F As shown, the filter 400 may further include a parallel resonant unit P25. According to embodiments of this disclosure, the parallel resonant unit P25 may have a second resonant frequency f2 and may be connected in parallel with any other parallel resonant unit, i.e., connected to the same connection node. For example, with... Figure 4A compared to, Figure 4D The difference is that the parallel resonant unit P25 can be connected to the same connection node N23 as the parallel resonant unit P23. For example, with Figure 4A compared to, Figure 4E The difference is that the parallel resonant unit P25 can be connected to the same connection node N24 as the parallel resonant unit P24. For example, with Figure 4B compared to, Figure 4F The difference is that the parallel resonant unit P25 and the parallel resonant unit P23 are connected to the same connection node N23.

[0076] According to embodiments of this disclosure, any two of the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit are connected to the same connection node.

[0077] Figures 6A to 6F An equivalent circuit diagram of an example of a filter 600 according to a third embodiment of the present disclosure is shown.

[0078] For the sake of brevity, Figures 6A to 6F The filter 600 shown is in conjunction with Figures 4A to 4F The same components of the filter 400 shown are indicated by the same reference numerals, and detailed descriptions of these same components will be omitted. The following will only describe... Figures 6A to 6F The filter 600 shown is Figures 4A to 4F The differences of the filter 400 shown will be explained in detail.

[0079] According to the third embodiment of this disclosure, such as Figure 6A As shown, Figures 6A to 6F The filter 600 shown is Figures 4A to 4FThe difference between the filter 400 shown is that the resonant frequency f4 of the parallel resonant unit P23 included in the filter 600 can be greater than the first resonant frequency f1, i.e., f4>f1, which can be referred to as the "fourth resonant frequency" in this document. The parallel resonant unit P23 is another specific example of a third parallel resonant unit.

[0080] According to embodiments of this disclosure, the parallel resonant unit P23 can generate a transmission zero. Figure 7 It shows Figure 6A A schematic diagram of the zeros on the right side of the passband of filter 600. Figure 7 The meaning and values ​​of the x and y coordinates in the figure Figure 3 Similar, therefore not in Figure 7 As shown in the image. Figure 7 As shown, point m11 represents a zero generated on the right side (high-frequency side) of the passband of filter 600 by one of the parallel resonant units P23 and P24 and the series resonant units S21 to S23, and point m12 represents a zero generated on the right side of the passband of filter 600 by another of the parallel resonant units P23 and P24 and the series resonant units S21 to S23. According to an embodiment of this disclosure, the parallel resonant frequency of the resonant unit that generates the zero m12 is far from the passband, which can effectively reduce the power dissipation density, thereby increasing the power capacity of the entire filter 600.

[0081] According to the third embodiment of this disclosure, by adjusting the resonant frequency of the parallel resonant unit P23, while ensuring a high roll-off on both sides of the passband of the filter 600, the resonant frequency of the parallel resonant unit on the right side of the passband of the control filter 600 can be shifted to a higher frequency, thereby obtaining a lower power dissipation density and improving the power capacity of the filter.

[0082] Although this article combines Figure 6A The circuit structure shown describes a filter 600 according to a third embodiment of the present disclosure, but the present disclosure is not limited thereto. Figures 6B to 6F The circuit structure of a filter 600 according to a third embodiment of the present disclosure is shown as another example.

[0083] Figures 6B to 6F The circuit structure shown is Figures 4B to 4F The circuit structures shown are completely identical in circuit topology, the only difference being the resonant frequency of the parallel resonant unit P23, so they will not be described again here.

[0084] By combining the first embodiment according to the present disclosure with the second embodiment according to the present disclosure, that is, by providing a parallel resonance unit in the parallel resonance unit of the filter with a third resonance frequency f3 greater than the second resonance frequency f2 and less than the first resonance frequency f1 and a fourth resonance frequency f4 greater than the first resonance frequency f1, control on both sides of the filter passband can be achieved to obtain a sharper roll-off characteristic, while obtaining a lower dissipation power density and improving the power capacity of the filter.

[0085] Figures 8A to 8E An equivalent circuit diagram showing an example of a filter 800 according to a fourth embodiment of the present disclosure is shown.

[0086] For simplicity, Figures 8A to 8E In the filter 800 shown, the components identical to those in Figures 4A to 4F and Figures 6A to 6F in the filters 400 and 600 shown are denoted by the same reference numerals, and detailed descriptions of these identical components will be omitted. Only the differences between the filter 800 shown below and Figures 8A to 8E the filters 400 and 600 shown in Figures 4A to 4F and Figures 6A to 6F will be described in detail below.

[0087] Figures 8A to 8E The filter 800 shown can be understood as Figures 4A to 4F the combination of the filter 400 described above and Figures 6A to 6F the filter 600 shown. For example, as shown in Figure 8A , the parallel resonance unit P22 of the filter 800 has a third resonance frequency f3 greater than the second resonance frequency f2 and less than the first resonance frequency f1 (i.e., f2 < f3 < f1), and the parallel resonance unit P23 of the filter 800 has a fourth resonance frequency f4 greater than the first resonance frequency f1 (f1 < f4). That is, in Figures 8A to 8E , f2 < f3 < f1 < f4, where f1 is the first resonance frequency and f2 is the second resonance frequency f2.

[0088] Although the filter 800 according to the fourth embodiment of the present disclosure is described herein in combination with the circuit structure shown in Figure 8A , the present disclosure is not limited thereto. Figures 8B to 8E The circuit structure of a filter 800 according to a fourth embodiment of the present disclosure is shown as another example. For example, compared with Figure 6B and Figure 6C , Figure 8B and Figure 8C are different in that the second resonator unit P242 of the parallel resonance unit P24 has a third resonance frequency f3. In addition, for example, compared with Figure 8C , Figure 8D The difference lies in that the second resonant subunit P212 of the parallel resonant unit P21 also has a third resonant frequency f3. Furthermore, for example, with... Figure 6F compared to, Figure 8E The difference is that the second resonant subunit P242 of the parallel resonant unit P24 has a third resonant frequency f3.

[0089] Furthermore, according to embodiments of this disclosure, a multiplexer is also provided, which includes the filter according to the above embodiments of this disclosure.

[0090] The filter and multiplexer including the filter disclosed herein can ensure very sharp roll-off characteristics on both sides of the passband, while reducing manufacturing difficulty and manufacturing-related errors. More importantly, the filter and multiplexer including the filter disclosed herein can slightly shift the resonant frequencies of the parallel resonant units controlling the left (low-frequency side) and right (high-frequency side) of the passband towards the low-frequency and high-frequency directions, respectively, thereby effectively reducing power dissipation density and increasing the overall power capacity of the filter.

[0091] Although this disclosure has been described with reference to exemplary embodiments thereof, those skilled in the art will understand that various modifications and variations may be made without departing from the spirit and scope of this disclosure as set forth in the claims.

Claims

1. A filter, comprising: Multiple series resonant units are connected in series between the input node and the output node of the filter, and each of the multiple series resonant units has a first resonant frequency; At least one first parallel resonant unit is connected in parallel between a connection node and a ground node, wherein the connection node is a node at the input and / or output of the series resonant unit, and the first parallel resonant unit has a second resonant frequency that is less than the first resonant frequency. as well as At least one second parallel resonant unit is connected in parallel between the connection node and the ground node, and includes a first resonant subunit and a second resonant subunit connected in series, wherein the resonant frequency of the first resonant subunit is greater than or equal to the first resonant frequency, and the resonant frequency of the second resonant subunit is greater than or equal to the second resonant frequency and less than the first resonant frequency. It also includes: at least one third parallel resonant unit, connected in parallel between the connection node and the ground node, wherein the resonant frequency of the third parallel resonant unit is greater than the second resonant frequency. The second parallel resonant unit and the third parallel resonant unit generate transmission zeros.

2. The filter according to claim 1, wherein, The third parallel resonant unit is connected in parallel with the first parallel resonant unit, or One of the at least one first parallel resonant unit is replaced by the third parallel resonant unit.

3. The filter according to claim 1 or 2, wherein, Each of the plurality of series resonant units, the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit is composed of an acoustic resonator.

4. The filter according to claim 3, wherein, The acoustic resonator is a surface acoustic wave resonator, a thin-film bulk acoustic wave resonator, a solid-state assembly acoustic wave resonator, or a Lamb wave resonator.

5. The filter according to claim 1 or 2, wherein, The first parallel resonant unit and / or the third parallel resonant unit includes an acoustic resonator or an acoustic resonator and an inductor connected in series between the connection node and the ground node.

6. The filter according to claim 1 or 2, wherein, The first resonator unit and / or the second resonator unit includes an acoustic resonator or a series circuit of an acoustic resonator and an inductor.

7. The filter according to claim 3, wherein, Both the first resonator unit and the second resonator unit are composed of acoustic resonators, and the acoustic resonators constituting the first resonator unit and the second resonator unit have the same area.

8. The filter according to claim 1 or 2, wherein, At least one of the plurality of series resonant units, the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit is composed of lumped elements including capacitors and inductors.

9. The filter according to claim 1 or 2, wherein, Any two of the first parallel resonant unit, the second parallel resonant unit, and the third parallel resonant unit are connected to the same connection node.

10. A multiplexer comprising a filter according to any one of claims 1 to 9.

Images