Filter and method of designing the same, multiplexer

Abstract

The application discloses a filter, a design method thereof and a multiplexer, the filter comprising an input port, a first transformer, a resonator circuit, a second transformer and an output port, the resonator circuit comprising N bandpass-stop resonators connected in sequence and used for providing reflection zero points and / or transmission zero points, N being a natural number greater than 0; the input port is connected with an input end of the first transformer, the output port is connected with an output end of the second transformer, and an output end of the first transformer and an input end of the second transformer are connected through the N bandpass-stop resonators. By simultaneously arranging a bandpass resonator and a band-stop resonator in the resonator part of the circuit, and by selecting the input quantity of the bandpass-stop resonator in the circuit to adjust the actual circuit parameters of the filter, the problem that the circuit of the existing filter can only realize bandpass or band-stop and cannot adjust parameters based on different system requirements is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of filter communication technology, and in particular to a filter and a design method thereof, and a multiplexer. BACKGROUND

[0002] The filter is a very important device of the radio frequency front end, which can filter out the out-of-band noise and improve the sensitivity of the circuit system. The traditional filter device is synthesized based on Butterworth or Chebyshev function. The uniform resonator and J transformer are cascaded.

[0003] With the continuous development of technology, the processing requirements of the communication system for signals are also changing, such as the diversity of communication frequency bands. The circuit structure of the bandpass filter in the prior art is not compatible with the design of bandpass and bandstop, which cannot meet the communication requirements and affects the performance of the entire communication system. SUMMARY

[0004] The main purpose of the present application is to provide a filter and a design method thereof, and a multiplexer, so as to solve the problem that the circuit of the existing filter can only realize bandpass or bandstop, and cannot adjust parameters based on different system requirements.

[0005] The first aspect of the present application provides a filter, comprising: an input port, a first transformer, a resonator circuit, a second transformer and an output port, the resonator circuit comprising N bandpass-bandstop resonators cascaded in sequence, for providing reflection zero and / or transmission zero, N being a natural number greater than 0.

[0006] The input port is connected with the input end of the first transformer, the output port is connected with the output end of the second transformer, and the output end of the first transformer and the input end of the second transformer are connected through N bandpass-bandstop resonators.

[0007] Optionally, the resonator circuit further comprises a third transformer arranged between two bandpass-bandstop resonators, for controlling the coupling between the two bandpass-bandstop resonators.

[0008] Optionally, the bandpass-bandstop resonator comprises at least one bandpass resonator and at least one bandstop resonator, and the output end of the bandpass resonator is directly connected with the input end of the bandstop resonator through the third transformer.

[0009] Optionally, the bandpass resonator and the bandstop resonator are each provided with M stop bands, M being a natural number; the stop band comprises at least one frequency-independent unit capacitor and frequency-independent reactance, and the unit capacitor and the reactance are connected in parallel.

[0010] The second aspect of the present application provides a multiplexer, the multiplexer comprising a plurality of filters as claimed in any preceding claim connected in parallel.

[0011] The third aspect of the present application provides a design method of a filter, the filter comprising an input port, a first transformer, a resonator circuit, a second transformer and an output port, the method comprising:

[0012] providing N bandpass bandstop resonators connected in sequence on the resonator circuit for providing reflection zero and / or transmission zero, N being a natural number greater than 0;

[0013] connecting the input port with an input end of the first transformer, connecting the output port with an output end of the second transformer, connecting an output end of the first transformer with an input end of the second transformer with the resonator circuit respectively, and controlling whether each of the bandpass bandstop resonators is connected with the first transformer and the second transformer.

[0014] Optionally, the controlling whether each of the bandpass bandstop resonators is connected with the first transformer and the second transformer comprises:

[0015] providing at least one bandpass resonator and at least one bandstop resonator on each of the bandpass bandstop resonators, wherein the bandpass resonator and the bandstop resonator are both provided with M stop bands, M being a natural number;

[0016] determining the type, the order and the number of channels of the filter based on the design parameters of the filter;

[0017] adjusting the stop bands of each of the bandpass resonators and each of the bandstop resonators based on the number of channels of the filter;

[0018] selecting resonators meeting the type of the filter and the order of the filter from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator to be connected with the first transformer and the second transformer.

[0019] Optionally, the type of the filter comprises a bandpass filter with high selectivity and multiple zeros, a bandpass filter with wide stop band suppression range and a multi-channel bandpass filter.

[0020] Optionally, if the type of the filter is a bandpass filter with high selectivity and multiple zeros, the selecting resonators meeting the type of the filter and the order of the filter from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator to be connected with the first transformer and the second transformer comprises:

[0021] selecting resonators equal to the multiple zeros from the at least one bandpass resonator or the at least one bandstop resonator and sequentially cascading to form a multi-stage resonator;

[0022] connecting the multi-stage resonator with the first transducer and the second transducer.

[0023] Optionally, if the type of the filter is a wide stop-band range bandpass filter, selecting resonators meeting the type of the filter and the order of the filter from the at least one adjusted bandpass resonator and / or the at least one adjusted bandstop resonator and connecting the resonators with the first transducer and the second transducer, comprises:

[0024] determining the proportion of the bandpass resonator and the bandstop resonator based on the type of the filter, and calculating the number of the bandpass resonator and the bandstop resonator based on the proportion and the multiple zeros;

[0025] selecting resonators corresponding to the number from the at least one bandpass resonator and the at least one bandstop resonator, and sequentially cascading the selected resonators to form a multi-stage resonator;

[0026] connecting the multi-stage resonator with the first transducer and the second transducer.

[0027] Beneficial effects:

[0028] In the technical scheme provided by the application, the filter comprises an input port, a first transducer, a resonator circuit, a second transducer and an output port, the resonator circuit comprises N bandpass and bandstop resonators sequentially cascaded, for providing reflection zeros and / or transmission zeros, N is a natural number greater than 0; the input port is connected with the input end of the first transducer, the output port is connected with the output end of the second transducer, and the output end of the first transducer and the input end of the second transducer are connected through the N bandpass and bandstop resonators. By simultaneously arranging the bandpass resonator and the bandstop resonator in the resonator part of the circuit, and adjusting the actual circuit parameters of the filter by selecting the input number of the bandpass and bandstop resonator in the circuit, the problem that the circuit of the existing filter can only realize bandpass or bandstop and cannot adjust the parameters based on different system requirements is solved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The first structure diagram of the filter provided by the application;

[0030] Figure 2 The second structure diagram of the filter provided by the application;

[0031] Figure 3 The third structure diagram of the filter provided by the application;

[0032] Figure 4 A flow chart of the design method of the filter provided by the present application;

[0033] Figure 5 A fourth structural schematic diagram of the filter provided by the present application;

[0034] Figure 6 A fifth structural schematic diagram of the filter provided by the present application;

[0035] Figure 7 A structural schematic diagram of the resonator circuit provided by the present application;

[0036] Figure 8 A sixth structural schematic diagram of the filter provided by the present application;

[0037] Figure 9 A seventh structural schematic diagram of the filter provided by the present application;

[0038] Figure 10 A structural schematic diagram of the multiplexer provided by the present application. DETAILED DESCRIPTION

[0039] The terms "first", "second", "third", "fourth" and the like in the description and claims of the present application, and above drawings (if there are) are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments described herein can be implemented in other than the order illustrated or described herein. In addition, the terms "comprise" or "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a list of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0040] In view of the problem that the existing filter circuit structure can only realize band-pass or band-stop, and the resonator cannot be adjusted to adapt to different system communication requirements, the present application provides a filter, by designing the circuit structure of the filter to contain a band-pass resonator and a band-stop resonator at the same time, then in use, according to the requirements of different communication systems, the on-off of the band-pass resonator and the band-stop resonator is adjusted to realize the design of different filters, thereby solving the defects of the prior art and improving the compatibility of the filter circuit.

[0041] The present application will be further described in detail through specific embodiments in combination with the drawings.

[0042] Reference should be made to Figures 1-3 ,Figure 1 The present invention provides a schematic diagram of a filter structure, which includes an input port 110, a first converter 120, a resonator circuit 130, a second converter 140, and an output port 150. The resonator circuit BPBSR130 includes N cascaded bandpass and bandstop resonators 131 for providing reflection zeros and / or transmission zeros, where N is a natural number greater than 0.

[0043] The input port 110 is connected to the input terminal of the first converter 120, and the output port is connected to the output terminal of the second converter 140. The output terminal of the first converter 120 and the input terminal of the second converter 140 are connected through N bandpass and bandstop resonators 131.

[0044] In this embodiment, the design of N is specifically selected based on the signal processing requirements of the communication system where the filter is located. For example, it can be one, five, etc. By selecting different values, multi-order resonators can be constructed, thereby obtaining multi-order filters.

[0045] like Figure 2 As shown, the resonator circuit 130 also includes a third converter 132 disposed between the two bandpass and bandstop resonators 131 for controlling the coupling between the two bandpass and bandstop resonators 131.

[0046] In this embodiment, the bandpass / bandstop resonator 131 can be adjusted to be a bandpass resonator (BSR) or a bandstop resonator (BPR) based on different parameter settings. That is, the bandpass / bandstop resonator 131 includes at least one bandpass resonator 1311 and at least one bandstop resonator 1312. The output terminal of the bandpass resonator 1311 and the input terminal of the bandstop resonator 1312 are directly connected through the third converter 132.

[0047] In practical applications, if the resonator circuit 130 includes a bandpass / bandstop resonator 131, such as Figure 3 As shown, it is a circuit schematic of a first-order filter. The filter includes an input terminal Suorce, multiple J converters (J1, ..., JN), a resonator circuit 130, and an output terminal Load. The input terminal Suorce is connected to the resonator circuit 130, and the output terminal Load is connected to the resonator circuit 130 through multiple J converters.

[0048] The resonator circuit 130 in the figure includes multiple bandpass resonators (BSRs), multiple J-converters, and multiple bandstop resonators (BPRs). By selecting the number of bandpass resonators (BSRs) and bandstop resonators (BPRs), the transmission zeros and reflection zeros are determined, thereby obtaining a filter that meets communication requirements.

[0049] In the embodiment, the band-pass resonator 1311 and the band-stop resonator 1312 are each provided with M stop bands 133, M being a natural number; the stop band 133 includes at least one frequency-independent unit capacitor and frequency-independent reactance connected in parallel.

[0050] In summary, through the implementation of the filter provided above, since the band-pass resonator and the band-stop resonator are provided at the same time, the adjustment of the filter parameters is realized by controlling the connection of the two with the transformer, and the compatibility of the filter in multiple scenarios is realized.

[0051] Please refer to Figure 4 The design method of the filter provided by the embodiment of the application includes the following steps:

[0052] S401, N band-pass and band-stop resonators are provided on the resonator circuit in sequence.

[0053] The band-pass and band-stop resonator is used to provide a reflection zero point and / or a transmission zero point, and N is a natural number greater than 0. The band-pass and band-stop resonator is provided with at least one band-pass resonator and at least one band-stop resonator, and the output end of the band-pass resonator is directly connected with the input end of the band-stop resonator through a third transformer.

[0054] In actual application, when the N band-pass and band-stop resonators are provided in sequence, the N is set based on the demand of communication, that is, the condition requirement of the out-of-band and in-band of the filter. For example, when a single frequency and a first-order band-pass filter is needed, the N band-pass and band-stop resonators provided in sequence can be set as a band-pass resonator BSR=2 and a band-stop resonator BPR=0. Figure 5 As shown in the equivalent circuit diagram, it only has an input, an output, a transformer and a BSR, and the BSR is provided with two stop bands represented by a frequency-independent unit capacitor s=jω and a frequency-independent reactance jB in parallel, that is, the unit corresponding to s+jω in the figure, wherein jB NRN is the equivalent symbol of the band-pass resonator.

[0055] S402, the input port is connected with the input end of the first transformer, the output port is connected with the output end of the second transformer, the output end of the first transformer and the input end of the second transformer are respectively connected with the resonator circuit, and whether each band-pass and band-stop resonator is connected with the first transformer and the second transformer is controlled.

[0056] In the embodiment, when controlling whether each of the bandpass and bandstop resonators is connected with the first and second transducers, specifically, by controlling whether the resonator circuit is a bandpass resonator or a bandstop resonator, at least one bandpass resonator and at least one bandstop resonator are arranged on each of the bandpass and bandstop resonators, wherein the bandpass resonator and the bandstop resonator are each provided with M stop bands, M being a natural number; the type, order and channel number of the filter are determined based on the design parameters of the filter; the stop bands of each of the bandpass resonators and each of the bandstop resonators are adjusted based on the channel number of the filter; and resonators meeting the type of the filter and the order of the filter are selected from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator and connected with the first and second transducers.

[0057] In the embodiment, the type of the filter includes a bandpass filter with high selectivity and multiple zeros, a bandpass filter with a wide stop band suppression range, and a multi-channel bandpass filter.

[0058] Specifically, if the type of the filter is a bandpass filter with high selectivity and multiple zeros, the step of selecting resonators meeting the type of the filter and the order of the filter from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator and connecting the resonators with the first and second transducers includes:

[0059] selecting resonators equal to the multiple zeros from the at least one bandpass resonator or the at least one bandstop resonator, and sequentially cascading the resonators to form a multi-order resonator;

[0060] connecting the multi-order resonator with the first and second transducers.

[0061] In actual application, as shown in Figure 6 , when the type of the filter is a bandpass filter with high selectivity and multiple zeros, an equivalent circuit diagram of the filter is shown. In the circuit, at least one bandpass resonator BSR and at least one bandstop resonator BPR in the resonator circuit are respectively set to BSR=2 and BPR=0 to obtain a first-order resonator, and then a plurality of such resonators are selected to constitute a multi-order filter, preferably, five orders are selected as an example as shown in Figure 6 .

[0062] Of course, the values of BSR and BPR can be determined according to actual needs, for example, as shown in Figure 7 , different first-order filters are realized based on different values of BSR and BPR, Figure 7 (a) and Figure 7(b) is respectively set BSR=1 and BPR=0, BSR=2 and BPR=0, to realize the resonator is set to the filter of the first order of the band-pass resonator, Figure 7 (c) is set BSR=3 and BPR=0, to realize the resonator is set to the filter of the double frequency first order of the band-pass resonator, Figure 7 (d) is set BSR=4 and BPR=0, to realize the resonator is set to the filter of the three frequency first order of the band-pass resonator, Figure 7 (e), Figure 7 (f), Figure 7 (h), and Figure 8 (g) is respectively set BSR=1 and BPR=1, BSR=2 and BPR=1, BSR=1 and BPR=2, BSR=2 and BPR=2, to realize the resonator is set to the filter of the first order of the mixed band-pass resonator and the band-stop resonator.

[0063] In the embodiment, when the type of the filter is the band-pass filter of the wide stop-band suppression range, the resonators satisfying the type of the filter and the order of the filter are selected from the adjusted at least one band-pass resonator and / or the adjusted at least one band-stop resonator and connected with the first transducer and the second transducer, comprising:

[0064] The proportion of the band-pass resonator and the band-stop resonator is determined based on the type of the filter, and the number of the band-pass resonator and the band-stop resonator is calculated based on the proportion and the multiple zeros;

[0065] The corresponding number of resonators is selected from the at least one band-pass resonator and the at least one band-stop resonator, and the selected resonators are cascaded in turn to form a multi-order resonator;

[0066] The multi-order resonator is connected with the first transducer and the second transducer.

[0067] In actual application, as shown in FIG. 1, the equivalent circuit diagrams of the filters of the first order and the fifth order are respectively shown, wherein Figure 8 (a) and Figure 8 (b) is a band-pass-stop resonator when BSR=0 and BPR=1, to obtain the filter of the first order; as shown in FIG. 1, Figure 8 (c) and (b) are the filters of the third order, which are respectively composed of two band-pass resonators of BSR=2 and BPR=0 and three band-stop resonators of BSR=0 and BPR=1. Figure 9

[0068] In the embodiment, when the type of the filter is the multi-channel band-pass filter, the number of stop-bands in the band-pass resonator or the band-stop resonator is controlled to realize the multi-frequency design. ​

[0069] As shown in Figure 9 Figure 9 The design of the dual-frequency in (a) is to control BSR=3 and BPR=0, to realize the first-order filter of dual-frequency. Figure 9 (b) is the first-order filter of triple-frequency, wherein BSR=4 and BPR=0.

[0070] Further, for the multi-order setting, the number of resonators is designed, as shown in Figure 9 (c) is the third-order filter of dual-frequency obtained by connecting three resonators with BSR=3 and BPR=0 in series. As shown in Figure 10 (d) is the third-order filter of triple-frequency obtained by connecting three resonators with BSR=4 and BPR=0 in series.

[0071] In summary, the filter is designed by the circuit structure provided above, which not only realizes the combination of bandpass and bandstop, but also improves the compatibility of the filter. The bandpass resonator and the bandstop resonator are arranged in the resonator part of the circuit at the same time, and the actual circuit parameters of the filter are adjusted by selecting the input number of the bandpass and bandstop resonator in the circuit, thereby solving the problem that the existing filter circuit can only realize bandpass or bandstop, and cannot adjust the parameters based on different system requirements.

[0072] Referring to ​ As shown in the figure, the multiplexer provided in the embodiment of the application includes a plurality of filters 1100 provided in any one of the above embodiments connected in parallel.

[0073] In the embodiment, the filter 1100 includes an input port, a first transformer, a resonator circuit, a second transformer, and an output port. The resonator circuit includes N bandpass and bandstop resonators connected in series, for providing reflection zero points and / or transmission zero points, and N is a natural number greater than 0.

[0074] The input port is connected with the input end of the first transformer, the output port is connected with the output end of the second transformer, and the output end of the first transformer and the input end of the second transformer are connected through the N bandpass and bandstop resonators.

[0075] Optionally, the resonator circuit further includes a third transformer arranged between two bandpass and bandstop resonators, for controlling the coupling between the two bandpass and bandstop resonators.

[0076] Optionally, the bandpass and bandstop resonator includes at least one bandpass resonator and at least one bandstop resonator, and the output end of the bandpass resonator is directly connected with the input end of the bandstop resonator through the third transformer.

[0077] ​Optionally, the band-pass resonator and the band-stop resonator are each provided with M stop bands, M being a natural number; the stop band includes at least one frequency-independent unit capacitor and frequency-independent reactance, the unit capacitor and the reactance being connected in parallel.

[0078] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of designing a filter, the filter comprising: The input port, the first transformer, the resonator circuit, the second transformer and the output port are characterized in that the method comprises: N bandpass bandstop resonators are arranged on the resonator circuit in sequence to provide reflection zero points and / or transmission zero points, N being a natural number greater than 0; The input port is connected to the input end of the first transformer, the output port is connected to the output end of the second transformer, the output end of the first transformer and the input end of the second transformer are connected to the resonator circuit respectively, and whether each bandpass bandstop resonator is connected to the first transformer and the second transformer is controlled; The control of whether each bandpass bandstop resonator is connected to the first transformer and the second transformer comprises: At least one bandpass resonator and at least one bandstop resonator are arranged on each bandpass bandstop resonator, wherein the bandpass resonator and the bandstop resonator are each provided with M stop bands, M being a natural number; Based on the design parameters of the filter, the type, order and frequency channel number of the filter are determined; Based on the frequency channel number of the filter, the stop bands of each bandpass resonator and each bandstop resonator are adjusted; The resonators that meet the type of the filter and the order of the filter are selected from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator to be connected to the first transformer and the second transformer.

2. The design method of claim 1, wherein The type of the filter includes a high-selectivity bandpass filter with multiple zero points, a wide-stop-band range bandpass filter and a multi-channel bandpass filter.

3. The method of designing according to claim 2, wherein, If the type of the filter is a high-selectivity bandpass filter with multiple zero points, the selection of the resonators that meet the type of the filter and the order of the filter from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator to be connected to the first transformer and the second transformer comprises: The resonators equal to the multiple zero points are selected from the at least one bandpass resonator or at least one bandstop resonator, and are sequentially cascaded to form a multi-order resonator; The multi-order resonator is connected to the first transformer and the second transformer.

4. The method of claim 2, wherein, If the type of the filter is a wide-stop-band range bandpass filter, the selection of the resonators that meet the type of the filter and the order of the filter from the adjusted at least one bandpass resonator and / or the adjusted at least one bandstop resonator to be connected to the first transformer and the second transformer comprises: The proportion of the bandpass resonator and the bandstop resonator is determined based on the type of the filter, and the number of the bandpass resonator and the bandstop resonator is calculated based on the proportion and the multiple zero points; The corresponding number of resonators are selected from the at least one bandpass resonator and at least one bandstop resonator, and the selected resonators are sequentially cascaded to form a multi-order resonator; The multi-order resonator is connected to the first transformer and the second transformer.

5. A filter, characterized by The filter is produced by the design method as claimed in any one of claims 1-4, and comprises an input port, a first transducer, a resonator circuit, a second transducer and an output port, the resonator circuit comprising N bandpass-stop resonators connected in series for providing reflection zeros and / or transmission zeros, N being a natural number greater than 0. The input port is connected to an input end of the first transducer, the output port is connected to an output end of the second transducer, and an output end of the first transducer is connected to an input end of the second transducer through the N bandpass-stop resonators.

6. The filter of claim 5, wherein, The resonator circuit further comprises a third transducer arranged between two of the bandpass-stop resonators for controlling the coupling between the two bandpass-stop resonators.

7. The filter of claim 6, wherein, The bandpass-stop resonator comprises at least one bandpass resonator and at least one band-stop resonator, and an output end of the bandpass resonator is directly connected to an input end of the band-stop resonator through the third transducer.

8. The filter of claim 7, wherein, The bandpass resonator and the band-stop resonator are each provided with M stop bands, M being a natural number, and each stop band comprises at least one frequency-independent unit capacitor and a frequency-independent reactance, the unit capacitor being connected in parallel with the reactance.

9. A multiplexer, characterized by The multiplexer comprises a plurality of filters as claimed in any one of claims 5-8 connected in parallel.

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