Double-passband band-pass filter

Abstract

The invention provides a dual-passband band-pass filter. The dual-passband band-pass filter comprises an input port, an output port, N band gap and bandwidth control units and N-1 inter-unit matching networks, wherein the N band gap and bandwidth control units are connected between the input port and the output port; each inter-unit matching network at least comprises an inductor which is connected between a node between the band gap and the bandwidth control unit and the ground; each band gap and bandwidth control unit comprises a series branch and at least one parallel branch, the series branch comprises at least one series resonator, each parallel branch is arranged between a node of the series branch and the ground and at least comprises one parallel resonator, and the resonant frequency of the parallel resonator is greater than that of the series resonator; the band gaps and the bandwidth control units are sequentially connected through series branches, and one parallel branch of at least one band gap and bandwidth control unit and the matching network between the adjacent units are connected to the same node. The filter provided by the invention is low in cost, small in size and low in dependence on the accuracy of the process.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic communication devices, and in particular to a dual-passband bandpass filter. Background Art

[0002] A dual-passband bandpass filter is a filter with two independent passbands, each of which corresponds to a specific range. Based on this characteristic, dual-passband bandpass filters are currently widely used in electronic devices that need to work in two frequency bands at the same time.

[0003] In the prior art, a dual-passband filter is usually formed by connecting two single-passband filters in parallel. Figure 1 The structure of the existing dual-passband filter is described with a specific embodiment. As shown in the figure, the dual-passband filter includes an input port P in , output port P out , and connected in parallel at the input port P in and output port P out The first single-pass bandpass filter 10 and the second single-pass bandpass filter 20 are arranged between them. The first single-pass bandpass filter 10 includes a series path and three parallel resonators. The series path starts from the input port P in To output port P out The direction includes the series resonator S 11 , series resonator S 12 , series resonator S 13 , series resonator S 14 , series resonator S 15 And the series resonator S 16 , the three parallel resonators are parallel resonators P 11 , parallel resonator P 12 , and the parallel resonator P 13 , where the parallel resonator P 11 One end is connected to the series resonator S 11 and series resonator S 12 The other end is connected through the inductor L 11 Ground, parallel resonator P 12 One end is connected to the series resonator S 13 and series resonator S 14 The node between the parallel resonator P 13 One end is connected to the series resonator S 15 and series resonator S 16 At the node between the parallel resonator P 12 The other end of the parallel resonator P 13 The other end is connected through a common inductor L12 The second single-pass bandpass filter 20 also includes a series path from the input port P to the output port P and three parallel resonators. in To output port P out The direction includes the series resonator S 21 , series resonator S 22 , series resonator S 23 , series resonator S 24 , series resonator S 25 And the series resonator S 26 , the three parallel resonators are parallel resonators P 21 , parallel resonator P 22 , and the parallel resonator P 23 , where the parallel resonator P 21 One end is connected to the series resonator S 21 and series resonator S 22 The other end is connected through the inductor L 21 Ground, parallel resonator P 22 One end is connected to the series resonator S 23 and series resonator S 24 At the node between the parallel resonator P 23 One end is connected to the series resonator S 25 and series resonator S 26 At the node between the parallel resonator P 22 The other end of the parallel resonator P 23 The other end is connected through a common inductor L 22 For the first single-passband filter 10 and the second single-passband filter 20, the resonant frequency of the parallel resonator is lower than the resonant frequency of the series resonator. In addition, as shown in the figure, the dual-passband filter also includes a matching inductor L 31 , matching inductor L 32 , matching inductor L 41 And matching inductor L 42 , where the matching inductor L 31 Connected in series to the input port P in and the first single-pass bandpass filter 10, a matching inductor L 32 A first single-pass bandpass filter 10 and an input port P are connected in series. out Between, matching inductor L 41 Connect in parallel to the input port P in and ground, matching inductor L 42 Connect in parallel to the input port P out and the earth.

[0004] The above-mentioned method of forming a dual-band bandpass filter by connecting two single-band bandpass filters in parallel has the advantage that the design theory is relatively simple, but its disadvantages are also obvious, that is, since two single-band bandpass filters are required, the existing dual-band bandpass filters have high manufacturing costs, large overall packaging size, and high dependence on process accuracy. Summary of the invention

[0005] In order to overcome the above defects in the prior art, the present invention provides a dual-passband bandpass filter, the dual-passband bandpass filter comprising:

[0006] An input port, an output port, N bandgap and bandwidth control units sequentially connected between the input port and the output port, and N-1 inter-unit matching networks, where N≥2 and N is an integer;

[0007] The N-1 inter-unit matching networks correspond one-to-one to the nodes between the N band gaps and bandwidth control units, and one end of each of the inter-unit matching networks is connected to the corresponding node and the other end is grounded, wherein each of the inter-unit matching networks at least includes an inductor;

[0008] Each of the bandgap and bandwidth control units includes a series branch and at least one parallel branch, the series branch includes a series resonator or two or more series resonators connected in series, one end of each of the parallel branches is connected to a node of the series branch and the other end is grounded, each of the parallel branches includes at least one parallel resonator, and the resonant frequency of the parallel resonator is greater than the resonant frequency of the series resonator, wherein the N bandgap and bandwidth control units are connected in sequence through the series branches, and there is at least one of the bandgap and bandwidth control units in which one of the parallel branches is connected to the same node as the inter-unit matching network adjacent to the bandgap and bandwidth control unit.

[0009] According to one aspect of the present invention, in the dual-passband bandpass filter, each of the bandgap and bandwidth control units is formed by cascading a first structure, a second structure, a third structure, or at least two of the above three structures; the first structure includes a series resonator and a parallel resonator, one end of the parallel resonator is connected to one end of the series resonator, and the other end is grounded; the second structure includes a series resonator and two parallel resonators, one end of the two parallel resonators is respectively connected to the two ends of the series resonator, and the other end is grounded; the third structure includes two series resonators and a parallel resonator, one end of the parallel resonator is connected to the node between the two series resonators, and the other end is grounded.

[0010] According to another aspect of the present invention, in the dual-band bandpass filter, the resonant frequencies of all the series resonators in the band gap and bandwidth control unit are the same or similar; and the resonant frequencies of all the parallel resonators in the band gap and bandwidth control unit are the same or similar.

[0011] According to another aspect of the present invention, in the dual-passband filter, each of the inter-unit matching networks is a first inductor.

[0012] According to another aspect of the present invention, in the dual-passband bandpass filter, the dual-passband bandpass filter also includes: an input matching network, which is arranged between the input port and the bandgap and bandwidth control unit adjacent thereto; and / or an output matching network, which is arranged between the output port and the bandgap and bandwidth control unit adjacent thereto.

[0013] According to another aspect of the present invention, in the dual-passband bandpass filter, for the case where the dual-passband bandpass filter includes the input matching network, the input matching network is a second inductor, and the second inductor is connected in series between the input port and the bandgap and bandwidth control unit adjacent thereto; for the case where the dual-passband bandpass filter includes the output matching network, the output matching network is a third inductor, and the third inductor is connected in series between the output port and the bandgap and bandwidth control unit adjacent thereto.

[0014] The dual-passband filter provided by the present invention comprises an input port, an output port, N (N≥2 and an integer) band gap and bandwidth control units connected in sequence between the input port and the output port, and N-1 inter-unit matching networks; the N-1 inter-unit matching networks correspond to the nodes between the N band gaps and bandwidth control units one by one, one end of each inter-unit matching network is connected to the corresponding node and the other end is grounded, and each inter-unit matching network at least comprises an inductor; each band gap and bandwidth control unit comprises a series branch and at least one parallel branch, the series branch comprises a series resonator or two or more series resonators in series, one end of each parallel branch is connected to the node of the series branch and the other end is grounded, each parallel branch comprises at least one parallel resonator, and the resonant frequency of the parallel resonator is greater than the resonant frequency of the series resonator; the N band gap and bandwidth control units are connected in sequence through the series branches, and there is at least one band gap and bandwidth control unit in which a parallel branch is connected to the same node as the inter-unit matching network adjacent to the band gap and bandwidth control unit. Since the present invention only needs to construct one filter to achieve dual-band performance, compared with the prior art that requires two single-band bandpass filters to be connected in parallel to form a dual-band bandpass filter, the dual-band bandpass filter provided by the present invention has the characteristics of low manufacturing cost, miniaturization, and low dependence on process accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0016] Figure 1 It is a circuit diagram of a dual-passband bandpass filter in the prior art;

[0017] Figure 2 is a circuit diagram of a dual-passband bandpass filter according to a specific embodiment of the present invention;

[0018] 3(a) and 3(b) are circuit diagrams of a first structure;

[0019] FIG3( c ) and FIG3( d ) are circuit diagrams of the second structure and the third structure, respectively;

[0020] Figure 4 and Figure 5 is a circuit diagram of a dual-passband bandpass filter according to two preferred embodiments of the present invention;

[0021] Figure 6 yes Figure 5 Small signal S-curve diagram of the dual-band pass filter shown.

[0022] The same or similar reference numerals in the drawings represent the same or similar components. DETAILED DESCRIPTION

[0023] In order to better understand and illustrate the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] The present invention provides a dual-passband bandpass filter, the dual-passband bandpass filter comprising:

[0025] An input port, an output port, N bandgap and bandwidth control units sequentially connected between the input port and the output port, and N-1 inter-unit matching networks, where N≥2 and N is an integer;

[0026] The N-1 inter-unit matching networks correspond one-to-one to the nodes between the N band gaps and bandwidth control units, and one end of each of the inter-unit matching networks is connected to the corresponding node and the other end is grounded, wherein each of the inter-unit matching networks at least includes an inductor;

[0027] Each of the bandgap and bandwidth control units includes a series branch and at least one parallel branch, the series branch includes a series resonator or two or more series resonators connected in series, one end of each of the parallel branches is connected to a node of the series branch and the other end is grounded, each of the parallel branches includes at least one parallel resonator, and the resonant frequency of the parallel resonator is greater than the resonant frequency of the series resonator, wherein the N bandgap and bandwidth control units are connected in sequence through the series branches, and there is at least one of the bandgap and bandwidth control units in which one of the parallel branches is connected to the same node as the inter-unit matching network adjacent to the bandgap and bandwidth control unit.

[0028] Next, we will combine Figure 2 The various components of the above dual-passband filter are described in detail.

[0029] Specifically, Figure 2 As shown, the dual-passband filter provided by the present invention includes an input port P in and output port P out , where the input port P in Used to input the signal to be filtered, output port P out Used to output the signal of a specific frequency obtained after filtering.

[0030] like Figure 2 As shown, the dual-passband filter provided by the present invention also includes N bandgap and bandwidth control units and N-1 inter-unit matching networks, where N≥2 and N is a positive integer. Nrepresents N bandgap and bandwidth control units, with inter-unit matching network B1, inter-unit matching network B2, ... and inter-unit matching network B N-1 represents N-1 inter-unit matching networks. Among them, the bandgap and bandwidth control unit A1, the bandgap and bandwidth control unit A2, ..., and the bandgap and bandwidth control unit A N Connect to the input port P in and output port P out The inter-unit matching network B1, the inter-unit matching network B2, ... and the inter-unit matching network B N-1 The nodes between the N band gaps and the bandwidth control units correspond to each other one by one, and one end of each inter-unit matching network is connected to the corresponding node and the other end is grounded, that is, the inter-unit matching network B i One end is connected to the bandgap and bandwidth control unit A i Bandgap and bandwidth control unit A i+1 The other end is grounded, where i=1, 2, ..., N-1.

[0031] For each bandgap and bandwidth control unit, it includes a series branch and at least one parallel branch. In this embodiment, the series branch includes at least one series resonator, wherein, for the case where the series branch includes two or more series resonators, the two series resonators are connected in series. Each parallel branch includes at least one parallel resonator. For each parallel branch, in a specific embodiment, the parallel branch only includes parallel resonators and the number of parallel resonators is one; in another specific embodiment, the parallel branch only includes parallel resonators and the number of parallel resonators is two or more, and the two or more parallel resonators are connected in series, or in parallel, or in a mixed manner of series and parallel; in another specific embodiment, the parallel branch includes at least one parallel resonator and a grounding inductor, and the at least one parallel resonator is connected to the ground through the grounding inductor. Those skilled in the art will appreciate that the above are only illustrative examples and should not be construed as limiting the parallel branch structure. For the sake of simplicity, all possible structures of the parallel branch are not listed here. Each parallel branch is connected in parallel between the series branch and the ground, that is, one end of each parallel branch is connected to a node on the series branch and the other end is grounded. The N bandgap and bandwidth control units are sequentially connected to the input port P through the series branch. in and output port P out Specifically, for the case of N=2, one end of the series branch in the bandgap and bandwidth control unit A1 is connected to the input port P inThe other end is connected to one end of the series branch in the bandgap and bandwidth control unit A2, and the other end of the series branch in the bandgap and bandwidth control unit A2 is connected to the output port P out For the case of N=3, one end of the series branch in the bandgap and bandwidth control unit A1 is connected to the input port P in The other end is connected to one end of the series branch in the bandgap and bandwidth control unit A2, the other end of the series branch in the bandgap and bandwidth control unit A2 is connected to one end of the series branch in the bandgap and bandwidth control unit A3, and the other end of the series branch in the bandgap and bandwidth control unit A3 is connected to the output port P out For the case of N=4, one end of the series branch in the bandgap and bandwidth control unit A1 is connected to the input port P in , the other end is connected to one end of the series branch in the bandgap and bandwidth control unit A2, the other end of the series branch in the bandgap and bandwidth control unit A2 is connected to one end of the series branch in the bandgap and bandwidth control unit A3, the other end of the series branch in the bandgap and bandwidth control unit A3 is connected to one end of the series branch in the bandgap and bandwidth control unit A4, and the other end of the series branch in the bandgap and bandwidth control unit A4 is connected to the output port P out For the case where N>4, the same procedure is followed and will not be described here for the sake of brevity.

[0032] In this embodiment, for N bandgap and bandwidth control units, there is at least one bandgap and bandwidth control unit, and at least one parallel branch in the bandgap and bandwidth control unit is connected to the same node as the inter-unit matching network adjacent to the bandgap and bandwidth control unit. From the perspective of the inter-unit matching network, among all the inter-unit matching networks, at least one inter-unit matching network is connected to the same node as at least one parallel branch in the adjacent bandgap and bandwidth control unit.

[0033] The present invention does not limit the specific structure of the bandgap and bandwidth control unit, which can be formulated accordingly according to actual design requirements. Preferably, each bandgap and bandwidth control unit is formed by cascading at least two of the first structure, the second structure, the third structure, or the above three structures. As shown in Figure 3 (a) and Figure 3 (b), the first structure is a Γ-type structure, which includes a series resonator S1 and a parallel resonator P1, one end of the parallel resonator P1 is connected to one end of the series resonator S1, and the other end is grounded. As shown in Figure 3 (c), the second structure is a π-type structure, which includes a series resonator S1 and two parallel resonators P1 and P2, wherein one end of the parallel resonator P1 is connected to one end of the series resonator S1, the other end of the parallel resonator P1 is grounded, one end of the parallel resonator P2 is connected to the other end of the series resonator S1, and the other end of the parallel resonator P2 is grounded. As shown in FIG3(d), the third structure is a T-type structure, which includes two series resonators S1 and S2 and a parallel resonator P1, one end of which is connected to the node between the series resonator S1 and the series resonator S2, and the other end is grounded. It should be noted here that for each structure constituting the bandgap and bandwidth control unit, the number of the structure can be only one or two or more. That is, each bandgap and bandwidth control unit includes a first structure, b second structures, and c third structures, wherein a, b, and c are integers greater than or equal to 0, and a, b, and c cannot be equal to 0 at the same time. For example, a first structure as shown in FIG3(a) and a second structure as shown in FIG3(c) (i.e., a=b=1, c=0) are cascaded to form a bandgap and bandwidth control unit with a two-series and three-parallel structure. For another example, two first structures as shown in FIG3(b) (i.e., a=2, b=c=0) are cascaded to form a bandgap and bandwidth control unit with a two-series and two-parallel structure. It can be understood by those skilled in the art that (1) the specific values ​​of a, b, and c are determined by actual design requirements; and (2) when the bandgap and bandwidth control unit includes multiple structures mentioned above, the order in which the multiple structures are cascaded is also determined by actual design requirements.

[0034] The bandgap and bandwidth control unit is used to determine the bandwidth of each of the two passbands in the dual-passband bandpass filter, and the bandgap between the two passbands, where the bandgap refers to the frequency difference between the two passband frequency bands. Among them, the suppression of the two passband gaps in the dual-passband bandpass filter and the bandwidth of each of the two passbands are related to the specific number of the bandgap and bandwidth control units, specifically, they are proportional, that is, the more the number of bandgap and bandwidth control units, the better the suppression of the two passband gaps of the dual-passband bandpass filter, and the larger the bandwidth of each of the two passbands. The width of the bandgap between the two passbands in the dual-passband bandpass filter is mainly determined by the frequency difference between the parallel resonator and the series resonator in the bandgap and bandwidth control unit (i.e., the difference between the resonant frequency of the parallel resonator and the resonant frequency of the series resonator). Specifically, the position of the transmission zero point of the left sideband of the high passband in the two passbands of the dual-passband bandpass filter is related to the resonant frequency of the parallel resonator, and the position of the transmission zero point of the right sideband of the low passband in the two passbands of the dual-passband bandpass filter is related to the resonant frequency of the series resonator. Therefore, in the dual-passband bandpass filter provided by the present invention, the resonant frequency of the parallel resonator in each bandgap and bandwidth control unit is greater than the resonant frequency of the series resonator, that is, for any bandgap and bandwidth control unit, the resonant frequency of each parallel resonator therein is greater than the resonant frequency of any series resonator in the bandgap and bandwidth control unit. The present invention does not impose any restrictions on the specific resonant frequencies of the parallel resonators and the series resonators in each bandgap and bandwidth control unit, which can be formulated accordingly according to actual design requirements. Preferably, the resonant frequencies of all series resonators in all bandgap and bandwidth control units are designed to be the same or similar, and the resonant frequencies of all parallel resonators in all bandgap and bandwidth control units are designed to be the same or similar. It can be understood by those skilled in the art that when the difference in the resonant frequencies of two resonators falls within the allowable range of process error, the resonant frequencies of the two resonators are considered to be the same, and when the difference in the resonant frequencies of the two resonators exceeds the allowable range of process error and the absolute value of the difference is less than 10MHz, the resonant frequencies of the two resonators are considered to be similar.

[0035] The inter-unit matching network plays the role of matching the passband. For each inter-unit matching network, it at least includes an inductor. In a preferred embodiment, each inter-unit matching network is implemented using a single inductor. It can be understood by those skilled in the art that in other embodiments, according to actual design requirements, the inter-unit matching network can also include other electronic components in addition to the inductor. For example, the inter-unit matching network can be an inductor and a capacitor connected in parallel, etc. All structures that can play the role of matching the passband are applicable to the inter-unit matching network in the present invention. For the sake of simplicity, all possible structures of the inter-unit matching network are no longer listed here.

[0036] Since the present invention only needs to construct one filter to achieve dual-band performance, compared with the existing technology that requires two single-band bandpass filters to be connected in parallel to form a dual-band bandpass filter, the dual-band bandpass filter provided by the present invention has the characteristics of low manufacturing cost, miniaturization, and low dependence on process accuracy.

[0037] Preferably, the dual-passband bandpass filter provided by the present invention also includes an input matching network and an output matching network for realizing impedance matching. Specifically, the input matching network is arranged between the dual-passband bandpass filter input port and the bandgap and bandwidth control unit adjacent thereto, and the output matching network is arranged between the dual-passband bandpass filter output port and the bandgap and bandwidth control unit adjacent thereto. In a specific embodiment, the input matching network is implemented by an inductor (hereinafter represented by the second inductor), and the second inductor is connected in series between the input port and the bandgap and bandwidth control unit adjacent thereto (i.e., the first bandgap and bandwidth control unit in the direction from the input port to the output port). The output matching network is also implemented by an inductor (hereinafter represented by the third inductor), and the third inductor is connected in series between the output port and the bandgap and bandwidth control unit adjacent thereto (i.e., the last bandgap and bandwidth control unit in the direction from the input port to the output port). It can be understood by those skilled in the art that: (1) The structure of the input matching network and the output matching network should not be limited to inductors. Any structure that can achieve impedance matching is applicable to the input matching network and the output matching network in the present invention, such as capacitors, and a combination of inductors and capacitors, etc. For the sake of simplicity, all possible structures of the input matching network and the output matching network are not listed here. (2) The input matching network should not be limited to being set in series between the input port and the adjacent bandgap and bandwidth control unit. Any method that can be set between the input port and the adjacent bandgap and bandwidth control unit is applicable to the present invention. For example, the input matching network can also be connected in parallel between the input port and the adjacent bandgap and bandwidth control unit (that is, one end of the input matching network is connected to the node between the input port and the adjacent bandgap and bandwidth control unit, and the other end is grounded). Similarly, the output matching network should not be limited to being set in series between the output port and the adjacent bandgap and bandwidth control unit. Any method that can be set between the output port and the adjacent bandgap and bandwidth control unit is applicable to the present invention. For example, the output matching network can also be connected in parallel between the output port and the adjacent bandgap and bandwidth control unit (that is, one end of the output matching network is connected to the node between the output port and the adjacent bandgap and bandwidth control unit, and the other end is grounded). (3) In other embodiments, according to actual design requirements, the dual-passband filter provided by the present invention can also include only an input matching network or an output matching network, and the present invention does not make any limitation on this.

[0038] Combine the following Figure 4 and Figure 5 The dual-passband bandpass filter provided by the present invention is described with two preferred embodiments.

[0039] In a preferred embodiment, if Figure 4 As shown, the dual-passband filter includes an input port P in , output port P out , two bandgap and bandwidth control units (hereinafter referred to as bandgap and bandwidth control unit A1 and bandgap and bandwidth control unit A2), an inter-unit matching network B1, an input matching network N in And the output matching network N out Specifically, the bandgap and bandwidth control unit A1 includes a series resonator S 11 , parallel resonator P 11 And the parallel resonator P 12 , parallel resonator P 11 One end is connected to the series resonator S 11 The input end of the parallel resonator P 12 One end is connected to the series resonator S 11 The output end of the resonator P 11 and parallel resonator P 12 The resonant frequencies of both are greater than the series resonator S 11 The bandgap and bandwidth control unit A2 includes a series resonator S 21 and parallel resonator P 21 , parallel resonator P 21 One end is connected to the series resonator S 21 The output end of the resonator P 21 The resonant frequency of the series resonator S 21 The resonant frequency of the input matching network N is 0. in Using the second inductor L in Implementation, output matching network N out Using the third inductor L out Among them, the second inductor L in One end is connected to the input port P in The other end is connected to the series resonator S in the bandgap and bandwidth control unit A1 11 The input end, bandgap and bandwidth control unit A1 series resonator S 11 The output end and the bandgap and bandwidth control unit A2 in series resonator S 21 The input end of the bandgap and bandwidth control unit A2 is connected to the series resonator S 21The output terminal and the third inductor L out The input terminal is connected to the third inductor L out The output port P out One end of the first inductor L1 is connected to the series resonator S 11 and series resonator S 21 In this embodiment, the inter-unit matching network B1 and the parallel resonator P in the bandgap and bandwidth control unit A1 are connected. 12 The two are connected to the input port P in and output port P out on the same node between them.

[0040] In another preferred embodiment, Figure 5 As shown, the dual-passband filter includes an input port P in , output port P out , three bandgap and bandwidth control units (hereinafter respectively referred to as bandgap and bandwidth control unit A1, bandgap and bandwidth control unit A2, and bandgap and bandwidth control unit A3), two inter-unit matching networks (hereinafter respectively referred to as inter-unit matching network B1 and inter-unit matching network B2), input matching network N in And the output matching network N out Specifically, the bandgap and bandwidth control unit A1 includes a series resonator S 11 and parallel resonator P 11 , parallel resonator P 11 One end is connected to the series resonator S 11 The input end of the resonator P 11 The resonant frequency of the series resonator S 11 The bandgap and bandwidth control unit A2 includes a series resonator S 21 , parallel resonator P 21 And the parallel resonator P 22 , parallel resonator P 21 One end is connected to the series resonator S 21 The input end of the parallel resonator P 22 One end is connected to the series resonator S 21 The output end of the resonator P 21 and parallel resonator P 22 The resonant frequency of the series resonator S 21 The bandgap and bandwidth control unit A3 includes a series resonator S 31 and parallel resonator P 31 , parallel resonator P 31 One end is connected to the series resonator S 31The output end of the resonator P 31 The resonant frequency of the series resonator S 31 The inter-unit matching network B1 is implemented by the first inductor L1, and the inter-unit matching network B2 is implemented by the first inductor L2. in Using the second inductor L in Implementation, output matching network N out Using the third inductor L out Among them, the second inductor L in One end is connected to the input port P in The other end is connected to the series resonator S in the bandgap and bandwidth control unit A1 11 The input end, bandgap and bandwidth control unit A1 series resonator S 11 The output end and the bandgap and bandwidth control unit A2 in series resonator S 21 The input end of the bandgap and bandwidth control unit A2 is connected to the series resonator S 21 The output end and the bandgap and bandwidth control unit A3 in series resonator S 31 The input end of the bandgap and bandwidth control unit A3 is connected to the series resonator S 31 The output terminal and the third inductor L out The input terminal is connected to the third inductor L out The output port P out One end of the first inductor L1 is connected to the series resonator S 11 and series resonator S 21 The other end is grounded, and one end of the first inductor L2 is connected to the series resonator S 21 and series resonator S 31 In this embodiment, the inter-unit matching network B1 and the parallel resonator P in the bandgap and bandwidth control unit A2 are connected. 21 The two are connected to the input port P in and output port P out At the same node between the two, the inter-unit matching network B2 and the parallel resonator P in the bandgap and bandwidth control unit A2 22 The two are connected to the input port P in and output port P out on the same node between them.

[0041] Please refer to Figure 6 , Figure 6 yes Figure 5 The small signal S curve of the dual-passband filter shown in FIG. 1 is a graph of a small signal S curve of a dual-passband filter, where curve 1 (solid line) is Figure 5 The amplitude-frequency response curve of the dual-passband bandpass filter shown in the figure, curve 2 (dashed line) is Figure 5 The return loss curve of the dual-band pass filter is shown in Figure 2. Figure 6 It can be seen that Figure 5 The bandwidth of the high passband in the dual-passband filter shown is 1180MHZ, the bandwidth of the low passband is 800MHZ, and the band gap width between the high passband and the low passband is 640MHZ, that is, a dual-passband filter with good performance is achieved using only seven resonators and four inductors.

[0042] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other components, units or steps, and the singular does not exclude the plural. Multiple components, units or devices stated in the system claim may also be implemented by one component, unit or device through software or hardware.

[0043] The above disclosures are only some preferred embodiments of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A dual-passband bandpass filter, the dual-passband bandpass filter comprising: An input port, an output port, N bandgap and bandwidth control units sequentially connected between the input port and the output port, and N-1 inter-unit matching networks, where N≥2 and N is an integer; The N-1 inter-unit matching networks correspond one-to-one to the nodes between the N band gaps and bandwidth control units, and one end of each of the inter-unit matching networks is connected to the corresponding node and the other end is grounded, wherein each of the inter-unit matching networks at least includes an inductor; Each of the bandgap and bandwidth control units includes a series branch and at least one parallel branch, the series branch includes a series resonator or two or more series resonators connected in series, one end of each of the parallel branches is connected to a node of the series branch and the other end is grounded, each of the parallel branches includes at least one parallel resonator, and the resonant frequency of the parallel resonator is greater than the resonant frequency of the series resonator, wherein the N bandgap and bandwidth control units are connected in sequence through the series branches, and there is at least one of the bandgap and bandwidth control units in which one of the parallel branches is connected to the same node as the inter-unit matching network adjacent to the bandgap and bandwidth control unit.

2. The dual-passband filter according to claim 1, wherein: Each of the bandgap and bandwidth control units is formed by a first structure, a second structure, a third structure, or a cascade connection of at least two of the above three structures; The first structure includes a series resonator and a parallel resonator, wherein one end of the parallel resonator is connected to one end of the series resonator and the other end is grounded; The second structure includes a series resonator and two parallel resonators, one end of the two parallel resonators is respectively connected to the two ends of the series resonator, and the other end of the two parallel resonators is grounded; The third structure includes two series resonators and a parallel resonator, one end of the parallel resonator being connected to a node between the two series resonators and the other end being grounded.

3. A dual-passband bandpass filter according to claim 1 or 2, wherein: All the band gaps are the same as or close to the resonant frequencies of all the series resonators in the bandwidth control unit; as well as All of the band gaps are the same as or close to the resonant frequencies of all parallel resonators in the bandwidth control unit.

4. The dual-passband filter according to claim 1, wherein: Each of the inter-unit matching networks is a first inductor.

5. The dual-passband filter according to claim 1, wherein: The dual-passband bandpass filter also includes: an input matching network, the input matching network being arranged between the input port and the bandgap and bandwidth control unit adjacent thereto; and / or An output matching network is provided between the output port and the bandgap and bandwidth control unit adjacent to the output port.

6. The dual-passband filter according to claim 5, wherein: In the case where the dual-passband filter includes the input matching network, the input matching network is a second inductor, and the second inductor is connected in series between the input port and the bandgap and bandwidth control unit adjacent thereto; In the case where the dual-passband filter includes the output matching network, the output matching network is a third inductor, and the third inductor is connected in series between the output port and the bandgap and bandwidth control unit adjacent thereto.

Images