CN217721150U - Multiplexer for improving second harmonic suppression - Google Patents
Multiplexer for improving second harmonic suppression Download PDFInfo
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- CN217721150U CN217721150U CN202222036344.0U CN202222036344U CN217721150U CN 217721150 U CN217721150 U CN 217721150U CN 202222036344 U CN202222036344 U CN 202222036344U CN 217721150 U CN217721150 U CN 217721150U
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Abstract
The present disclosure relates to a multiplexer for improving second harmonic suppression, the multiplexer including a transmission filter, a reception filter, and a second harmonic suppression circuit, an output node of the transmission filter being connected to an antenna node via a common node, and the transmission filter including a series resonant unit and a parallel resonant unit; an input node of the reception filter is connected to the antenna node via a common node, and the reception filter includes a series resonant unit and a parallel resonant unit; the second harmonic suppression circuit is arranged between the common node and the antenna node and used for suppressing the second harmonic of the multiplexer. By adopting the scheme, signals with second harmonic can be filtered, and the second harmonic suppression capability of the multiplexer is improved.
Description
Technical Field
The present disclosure relates to the field of electronic circuit technology, and in particular, to a multiplexer capable of improving second harmonic suppression.
Background
With the development of wireless communication applications, the demand for data transmission rate is higher and higher, and the data transmission rate corresponds to high utilization rate of spectrum resources and complexity of spectrum. The complexity of the communication protocol imposes stringent requirements on the various performances of the rf system, and the multiplexers play a crucial role in the rf front-end module. And with the increasing popularity of 5G technology, the demand of various multiplexers is also increasing.
Currently, multiplexers based on acoustic resonators have the advantages of steep edge-roll-off (roll-off) characteristics, high selectivity, high power capacity, and strong electrostatic Discharge (ESD) resistance, and are increasingly widely used. However, it should be noted that the suppression of the harmonic generated by the non-sinusoidal current generated by the non-linear load, especially the second harmonic generated by the amplitude variation, is still a problem to be solved by the multiplexer.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem that the second harmonic that exists of multiplexer based on acoustic resonator is difficult to restrain among the prior art, this disclosure provides a multiplexer that promotes second harmonic suppression, and this kind of multiplexer includes:
a transmission filter whose output node is connected to an antenna node via a common node, and which includes a series resonant unit and a parallel resonant unit;
a reception filter whose input node is connected to the antenna node via a common node and includes a series resonant unit and a parallel resonant unit;
and the second harmonic suppression circuit is arranged between the common node and the antenna node and is used for suppressing the second harmonic of the multiplexer.
Optionally, the second harmonic rejection circuit comprises a capacitor and/or an inductor, and the capacitor is arranged in series or in parallel with the antenna node and the inductor is arranged in series or in parallel with the antenna node.
Optionally, the second harmonic rejection circuit comprises an inductor connected in series between the common node and the antenna node, an
A capacitor connected in parallel between the common node and the antenna node.
Optionally, the capacitor is connected between a connection path from the common node to the antenna node and a ground; one end of the inductor is connected to the common node, the other end of the inductor is connected to one end of the capacitor and the antenna node, and the other end of the capacitor is grounded.
Optionally, the imaginary value of the shunt impedance of the transmit filter and the receive filter is a negative value.
Optionally, the reflection coefficient phase is between 180 degrees and 360 degrees.
Optionally, the reflection coefficient phase is between 270 degrees and 360 degrees.
Optionally, each series resonant cell in the transmit filter is connected in series between the input node of the transmit filter and the common node; each series resonant cell in the receive filter is connected in series between an output node of the receive filter and the common node.
Optionally, the parallel resonant unit is connected in parallel between a connection node and a ground node, where the connection node is a node on a connection path of two adjacent series resonant units.
Optionally, the series resonant unit and/or the parallel resonant unit comprises an integral acoustic wave resonator.
Embodiments in the present disclosure can achieve at least the following advantages or benefits:
the multiplexer provided in this embodiment includes a transmitting filter, a receiving filter, and a second harmonic suppression circuit, where the second harmonic suppression circuit is disposed between an antenna node and a common node (i.e., a connection node between an output node of the transmitting filter and an input node of the receiving filter), and when the transmitting filter is in an operating state, a signal output by the transmitting filter enters the second harmonic suppression circuit, and is filtered by the second harmonic suppression circuit, so that a second harmonic in the signal entering the antenna node is reduced; when the receiving filter is in a working state, the signal output from the antenna node enters the second harmonic suppression circuit, and the second harmonic in the signal entering the receiving filter is reduced through the filtering processing of the second harmonic suppression circuit, so that the second harmonic suppression capability of the multiplexer can be effectively improved by arranging the second harmonic suppression circuit.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.
Fig. 1 is an equivalent circuit diagram of a multiplexer according to an embodiment of the present application;
FIG. 2 is an equivalent circuit diagram of a second harmonic suppression circuit in an embodiment;
FIG. 3 is an equivalent circuit diagram of several other embodiments of a second harmonic rejection circuit;
fig. 4 shows an equivalent circuit diagram applied to an embodiment of a B1 duplexer;
FIG. 5 is a Smith chart showing impedance characteristics of a transmitting filter and a receiving filter before a second harmonic suppression circuit is provided in the embodiment;
FIG. 6 is a schematic diagram illustrating the impedance matching of the second harmonic suppression circuit in an embodiment;
fig. 7 is a smith chart showing impedance characteristics of the transmission filter and the reception filter after impedance matching by providing the second harmonic suppression circuit in the embodiment.
The reference numerals in the drawings denote:
100 is a second harmonic suppression circuit; 110 is a transmit filter; 120 is a receiving filter; 101 is an inductor; 102 is a capacitor; 1011 is a first inductor; and 1012 is the second inductor.
Detailed Description
In this specification, it will also be understood that when an element is referred to as being "on," "connected to," or "coupled to" other elements relative to the other elements, such as on, "connected to," or "coupled to" the other elements, the one element may be directly on, connected or coupled to the one element, or an intervening third element may also be present. In contrast, when an element is referred to in this specification as being "directly on," "directly connected to" or "directly coupled to" another element, there are no intervening elements present therebetween.
The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout. Also, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity of illustration.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly dictates otherwise. For example, "an element" means the same as "at least one element" unless the context clearly dictates otherwise. "at least one of" should not be construed as limited to the quantity "one". "or" means "and/or". The term "and/or" includes any and all combinations of at least one of the associated listed items.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meaning as is in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "comprises" indicates a property, a quantity, a step, an operation, an element, a component or a combination thereof, but does not exclude other properties, quantities, steps, operations, elements, components or combinations thereof.
Hereinafter, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.
Fig. 1 shows an equivalent circuit diagram of a multiplexer according to an embodiment of the present disclosure. Those skilled in the art will recognize that the term "multiplexer" as used herein can be any of a variety of types of devices, such as duplexers, triplexers, quadroplexers, and the like. Therefore, although the multiplexer of the present disclosure is described as a duplexer in fig. 1, a person skilled in the art can easily extend the multiplexer to other types such as a triplexer, a quadroplexer, and the like based on the duplexer shown in fig. 1. In view of these expansion techniques, which are known to those skilled in the art, the following description will not describe its details in more detail in the interest of brevity.
As shown in fig. 1, the duplexer may include a Transmit (Tx) filter 110 and a Receive (Rx) filter 120.
As mentioned above, the duplexer can be easily extended to other types of multiplexers such as triplexers, quadroplexers, etc. by adding more transmit filters and/or receive filters, and all such extensions are intended to be within the scope of the present disclosure.
As shown in fig. 1, the output node NTxout of the transmit filter 110 and the input node TRxin of the receive filter 120 are each connected to a common node, i.e., the node between NTxout and TRxin in fig. 1, which is coupled to the antenna node. And as shown in fig. 1, a second harmonic (H2) suppression circuit 100 is provided between the antenna node and the common node. The second harmonic rejection circuit 100 described above is used to filter out the second harmonic between the transmit filter 110 and the antenna node, and/or filter out the second harmonic between the receive filter 120 and the antenna node.
As shown in fig. 1, the output node NTxout of the transmission filter 110 is coupled to the antenna node via the second harmonic suppression circuit 100, and the transmission filter 110 specifically includes a series resonant cell and a parallel resonant cell connected in a ladder configuration.
Those skilled in the art will recognize that although in fig. 1, the transmitting filter 110 is a 3-ladder filter including the first to third series resonant cells S1101 to S1103 and the first to third parallel resonant cells P1101 to P1103, the present disclosure is not limited thereto, and the specific number and connection relationship of the series resonant cells and the parallel resonant cells may be set according to the needs of a specific application. In accordance with embodiments of the present disclosure, the transmit filter 110 may be a ladder filter of any order or a filter having other topologies and may include any number of series resonant cells and parallel resonant cells, all of which variations are intended to be within the scope of the present disclosure.
As shown in fig. 1, the first to third series resonant units S1101 to S1103 are sequentially connected in series between the output node NTxout and the input node NTxin. Further, an output impedance matching unit (not shown in the drawing) may be further connected in series and/or in parallel between the output node NTxout and the first series resonance unit S1101, and an output impedance matching unit (not shown in the drawing) may be further connected in series and/or in parallel between the third series resonance unit S1103 and the input node NTxin. The input impedance matching unit and the output impedance matching unit may include impedance matching elements such as an inductor, a capacitor, a resonator, etc., or matching units composed of them in common.
Further, as shown in fig. 1, the first to third parallel resonant units P1101 to P1103 are connected in parallel between a node at the input and/or output of the first to third series resonant units S1101 to S1103 and a ground node.
Further, as shown in fig. 1, the input node NRxin of the reception filter 120 is coupled to the antenna node via the second harmonic suppression circuit 100, and the reception filter 120 specifically includes a series resonant unit and a parallel resonant unit connected in a ladder configuration.
Those skilled in the art will recognize that although the reception filter 120 is a 3-ladder filter including the first to third series resonant units S1201 to S1203 and the first to third parallel resonant units P1201 to P1203 in fig. 1, the present disclosure is not limited thereto. According to the embodiment of the present disclosure, the receiving filter 120 may be a ladder filter of any order or a filter having other topologies and may include any number of series resonant cells and parallel resonant cells, and all such variations are intended to be within the scope of the present disclosure.
Furthermore, although the receive filter 120 has the same circuit topology as the transmit filter 110 in fig. 1, i.e., each is a 3-step filter, the present disclosure is not limited thereto. According to an embodiment of the present disclosure, the receive filter 120 may have a different circuit topology than the transmit filter 110, i.e., may be a ladder filter of another order than 3 or a filter having another circuit topology, and all such variations are intended to be within the scope of the present disclosure.
As shown in fig. 1, the first to third series resonant units S1201 to S1203 are sequentially connected in series between an input node NRxin and an output node NRxout. Further, an input impedance matching unit (not shown in the drawing) may be further connected in series and/or in parallel between the input node NRxin and the first series resonance unit S1201, and an output impedance matching unit (not shown in the drawing) may be further connected in series and/or in parallel between the third series resonance unit S1203 and the output node NRxout. The input impedance matching unit and the output impedance matching unit may include impedance matching elements such as an inductor, a capacitor, a resonator, etc., or matching units composed of them in common.
Further, as shown in fig. 1, the first to third parallel resonant units P1201 to P1203 are connected in parallel between a node at the input and/or output of the first to third series resonant units S1201 to S1203 and a ground node.
Further, those skilled in the art will recognize that although the transmit filter 110 and the receive filter 120 according to embodiments of the present disclosure are described herein with reference to ladder filters as an example, the present disclosure is not limited thereto. One skilled in the art can readily envision applying the inventive concepts of the present disclosure to multiplexers based on other filter circuit topologies besides ladder filters in light of the teachings of the present disclosure.
The first to third series resonance units S1101 to S1103, the first to third parallel resonance units P1101 to P1103 of the transmission filter 110, and the first to third series resonance units S1201 to S1203, the first to third parallel resonance units P120 to P1203 of the reception filter 120 may be collectively referred to as "resonance units" in the present disclosure. Those skilled in the art will recognize that the "resonant unit" referred to in this disclosure may be comprised of a single resonator, or may be comprised of a series and/or parallel circuit of a resonator and an inductor and/or capacitor. For example, each of the first to third parallel resonant units P1101 to P1103 of the transmission filter 110 and the first to third parallel resonant units P1201 to P1203 of the reception filter 120 may be constituted by a resonator and an inductor connected in series between a connection node and a ground node. Furthermore, it will be appreciated by those skilled in the art that the term "resonant unit" as used herein may also include resonant units consisting of capacitive elements, such as capacitors, and inductive elements, such as inductors. All such variations are intended to be within the scope of the present disclosure.
The second harmonic suppression circuit 100 according to the present disclosure is exemplarily configured as shown in fig. 2, and the second harmonic suppression circuit 100 is disposed between the common node and the antenna node to suppress the second harmonic of the multiplexer.
The technical idea of this embodiment is to add the second harmonic suppression circuit 100 between the multiplexer transmission filter 110/reception filter 120 and the antenna, thereby achieving impedance matching by the second harmonic suppression circuit 100 while suppressing harmonics.
According to an embodiment of the present disclosure, the second harmonic rejection circuit 100 includes a capacitor and/or an inductor in series and/or parallel with the antenna node.
In one exemplary embodiment as shown in fig. 2, the second harmonic rejection circuit 100 includes an inductor 101 and a capacitor 102, the inductor 101 being connected in series between the common node and the antenna node, and the capacitor 102 being connected in parallel between the common node and the antenna node.
According to the embodiment of the present disclosure, as shown in fig. 2, a capacitor 102 is connected between a connection path of the common node to the antenna node and the ground. In a preferred embodiment, inductor 101 is closer to the common node than capacitor 102, i.e. one end of inductor 101 is connected to the common node, the other end of inductor 101 is connected to one end of capacitor 102 and to the antenna node, and the other end of capacitor 102 is connected to ground.
The second harmonic suppression circuit 100 is disposed between the antenna node and the common node, and the second harmonic suppression circuit 100 can effectively increase the second harmonic suppression of the multiplexer; specifically, the second harmonic suppression circuit 100 includes an inductor 101 connected in series between the transmission filter 110 and the antenna node, which has a small resistance to low-frequency signals and a large resistance to high-frequency signals; preferably, the second harmonic suppression circuit 100 further includes a capacitor 102 connected in parallel to the transmission filter 110, and having a small attenuation for low frequency signals and a large attenuation for high frequency signals, so as to provide a low pass characteristic between the transmission filter 110 and the antenna node, and to filter out a part of harmonics, especially the second harmonic, in the signal output by the transmission filter 110, and ideally achieve a second harmonic suppression characteristic of about-10 dBm.
In another exemplary embodiment, as shown in section a of fig. 3, a second harmonic rejection circuit 100 includes an inductor 101 connected in series between the common node and the antenna node and a capacitor 102 connected in parallel between the common node and the antenna node. Also, inductor 101 is further from the common node than capacitor 102. That is, one end of the inductor 101 is connected to the antenna node, the other end of the inductor 101 is connected to one end of the capacitor 102 and the common node, and the other end of the capacitor 102 is grounded.
In another exemplary embodiment, as shown in section b of fig. 3, the second harmonic rejection circuit 100 includes a capacitor 102 connected in series between the common node and the antenna node and an inductor 101 connected in parallel between the common node and the antenna node. The inductor 101 is closer to the common node than the capacitor 102, that is, one end of the capacitor 102 is connected to the antenna node, the other end of the capacitor 102 is connected to one end of the inductor 101 and the common node, and the other end of the inductor 101 is grounded.
In another exemplary embodiment, as shown in part c of fig. 3, the second harmonic suppression circuit 100 includes two inductors disposed differently, and specifically, the second harmonic suppression circuit 100 includes a first inductor 1011 connected in series between the common node and the antenna node and a second inductor 1012 connected in parallel between the common node and the antenna node, i.e., one end of the first inductor 1011 is connected to the antenna node, the other end of the first inductor 1011 is connected to one end of the second inductor 1012 and the common node, and the other end of the second inductor 1012 is grounded.
In one embodiment, taking the B1 duplexer as an example, in the prior art, at the antenna node position, the parallel impedance of the transmitting filter and the receiving filter is set at the lower left corner of the smith circle, i.e. the phase of the reflection coefficient is 180 degrees to 270 degrees and near the conductance circle of 0.02S, and then 50 ohm matching is realized through the parallel inductance.
According to the embodiment of the present disclosure, with the second harmonic suppression circuit 100 described above, impedance matching is performed while suppressing harmonics. Taking the B1 duplexer configured as shown in fig. 4 as an example, unlike the prior art, as shown in fig. 5, the embodiment of the present disclosure sets the parallel impedance of the transmit filter and the receive filter in the lower half circle of the smith circle, i.e., the port reflection coefficient is between 180 and 360 degrees. And as indicated by the dashed line in fig. 4, by connecting an inductor 101 of 3.7nH in series and a capacitor 102 of 1.3pF in parallel in the antenna node, 50 ohm matching of the parallel impedance of the transmit filter and the receive filter in the duplexer can be achieved (the matching process is shown in fig. 6), and the smith chart after matching is shown in fig. 7. As can be seen from comparing fig. 7 and fig. 5, by providing the above-mentioned inductor 101 (i.e., the series inductance in fig. 6) and the capacitor 102 (i.e., the parallel capacitance in fig. 6), the transmission filter terminal impedance points m34 and m35 and the reception filter terminal impedance points m36 and m37 of the present embodiment are closer to the origin (50 ohm impedance matching point) in fig. 7, and the impedance matching effect is better.
The second harmonic suppression circuit can not only complete the parallel impedance matching of the transmit filter and the receive filter, but also increase the second harmonic suppression of the duplexer as before. Specifically, due to its low-pass characteristic, part of the second harmonic signal output from the transmit filter can be filtered out, so that the second harmonic rejection capability of the duplexer reaches about-10 dBm.
According to an alternative embodiment of the present disclosure, the imaginary value of the parallel impedance of the transmit filter and the receive filter is negative, i.e. the phase of the reflection coefficient is between 180 and 360 degrees. That is, the characteristic impedance is located in any position within quadrant 3 and quadrant 4 of the smith chart.
According to an alternative embodiment of the present disclosure, the phase of the reflection coefficient of the impedance values of the parallel impedances of the transmit filter and the receive filter is between 270 degrees and 360 degrees. That is, its characteristic impedance is within quadrant 4 of the smith chart. On the premise of this, the second harmonic suppression circuit can suppress harmonics and simultaneously realize 50 Ω impedance matching.
In the above embodiment, the inductor 101 connected in series in the second harmonic suppression circuit can shift the impedance point of the parallel impedances of the transmission filter and the reception filter to the right hand along the equal resistance circle based on the representation in the smith chart; the capacitor 102 connected in parallel to the second harmonic suppression circuit can shift the impedance point of the parallel impedance of the transmission filter and the reception filter to the right hand along the equal conductance circle, and can finally match the impedance point to the origin (impedance matching point).
According to an embodiment of the present disclosure, the resonance units of the transmission filter 110 and the reception filter 120 may be constituted by resonators. According to embodiments of the present disclosure, parameters thereof may be adjusted by changing the piezoelectric material of the resonator or adjusting doping elements, doping concentrations, and/or doping combinations of the piezoelectric material of the resonator.
According to the embodiment of the present disclosure, it is preferable that the series resonance unit (S1101, S1102, and S1103) and the parallel resonance unit (P1101, P1102, and P1103) of the emission filter have substantially the same first electromechanical coupling coefficient; and the series resonant unit (S1201, S1202, and S1203) and the parallel resonant unit (P1201, P1202, and P1203) of the reception filter have substantially the same second electromechanical coupling coefficient, and preferably, the above-mentioned first electromechanical coupling coefficient is higher than the second electromechanical coupling coefficient.
It will be understood by those skilled in the art that the electromechanical coupling coefficients of the resonant cells recited herein may be considered as the electromechanical coupling coefficients of the resonators comprised by the resonant cells. In other words, the "electromechanical coupling coefficient of the resonance unit" and the "electromechanical coupling coefficient of the resonator" have the same technical meaning herein.
According to an embodiment of the present disclosure, the resonators of the respective resonance units constituting the transmission filter 110 and the reception filter 120 may be acoustic resonators, for example: a surface acoustic resonator, a thin film bulk acoustic resonator, a solid mount acoustic resonator, or a lamb wave resonator. Acoustic resonators generally have a sandwich structure of a lower electrode, a piezoelectric layer and an upper electrode fabricated on a substrate, the piezoelectric layer being made of a piezoelectric material with electromechanical transduction capability, for example: alN or doped AlN for converting between acoustic signals (sound waves) and electric signals, piezoelectric material and acoustic resonator using the same having a figure of merit FOM determined by an electromechanical coupling coefficient kt2Determined in conjunction with the quality factor Q, i.e. FOM = kt2* Q, wherein the electromechanical coupling coefficient represents the coupling and conversion capacity between the sound energy and the electric energy of the piezoelectric material, and the value of the electromechanical coupling coefficient is in direct proportion to the bandwidth of the working frequency band. Since acoustic resonators are known to the person skilled in the art, their details are not described in greater detail herein for the sake of brevity.
According to the embodiment of the present disclosure, the resonator of each resonance unit may have different types of piezoelectric materials, and the adjustment of the electromechanical coupling coefficient may be achieved by changing the piezoelectric materials of the resonators. For example, to obtain a high electromechanical coupling coefficient, li may be used(Nb,Ta)O3As the piezoelectric material, and in order to obtain a low electromechanical coupling coefficient, alN may be used as the piezoelectric material.
Alternatively or in combination, the resonators of the respective resonance units may also have the same type of piezoelectric material according to embodiments of the present disclosure. It should be noted that the "same type of piezoelectric material" referred to herein refers to a piezoelectric material in which the host is the same, for example AlN or AlN doped with another element may be considered herein as the same type of piezoelectric material. According to the embodiment of the disclosure, the adjustment of the electromechanical coupling coefficient can be realized by adjusting the doping element, the doping concentration and/or the doping combination of the piezoelectric material of the resonator.
According to embodiments of the present disclosure, the piezoelectric material of the resonator may include, but is not limited to: wurtzite structure, for example: alN, znO; perovskite structures, for example: baTiO 23、Pb(Ti,Zr)O3、Li(Nb,Ta)O3Or (K, na) NbO3(ii) a And organic piezoelectric materials such as: polyvinylidene fluoride (PVDF), and the like.
As a specific example, if it is desired to obtain a resonator having a low electromechanical coupling coefficient, the piezoelectric material may employ pure AlN, alN having a low doping concentration, or AlN doped with an element for reducing the electromechanical coupling coefficient. According to embodiments of the present disclosure, doping elements for reducing the electromechanical coupling coefficient include, but are not limited to B, ga and In.
Further, as a specific example, if it is desired to obtain a resonator having a high electromechanical coupling coefficient, the piezoelectric material may employ AlN having a high doping concentration, alN doped with an element for increasing the electromechanical coupling coefficient, or a stack having a plurality of doped AlN layers having different doping concentrations. According to embodiments of the present disclosure, doping elements for increasing the electromechanical coupling coefficient include, but are not limited to, ti, sc, mg, zr, hf, sb, Y, sm, eu, er, ta, and Cr.
In the above preferred embodiment, on the basis of suppressing the second harmonic and realizing the impedance matching, it is further possible to realize a multiplexer having a high insertion loss and a high isolation without adding additional components or manufacturing process steps by adjusting the electromechanical coupling coefficients of the respective resonance units of the transmission filter and the reception filter included in the multiplexer.
According to an embodiment of the present disclosure, some of the resonance units of the transmission filter 110 and the reception filter 120 may further include a resonance unit configured of a capacitive element (e.g., a capacitor) and an inductive element (e.g., an inductor).
According to the above embodiments of the present disclosure, the second harmonic suppression circuit connected to the antenna node can effectively increase the second harmonic suppression of the multiplexer, and due to the low-pass characteristic of the suppression circuit, part of the signal with the second harmonic output by the transmission filter can be filtered out, and the impedance matching of the parallel impedance of the transmission filter and the reception filter can be simultaneously achieved.
The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments disclosed in the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A multiplexer for enhancing second harmonic suppression, comprising:
a transmission filter whose output node is connected to an antenna node via a common node, and which includes a series resonant unit and a parallel resonant unit;
a reception filter whose input node is connected to the antenna node via a common node and includes a series resonant unit and a parallel resonant unit;
and the second harmonic suppression circuit is arranged between the common node and the antenna node and is used for suppressing the second harmonic of the multiplexer.
2. The multiplexer of claim 1, wherein the second harmonic rejection circuit comprises a capacitor and/or an inductor, and wherein the capacitor is arranged in series or in parallel with the antenna node and the inductor is arranged in series or in parallel with the antenna node.
3. The multiplexer of claim 2, wherein the second harmonic rejection circuit comprises an inductor connected in series between the common node and the antenna node, and
a capacitor connected in parallel between the common node and the antenna node.
4. The multiplexer of claim 3, wherein the capacitor is connected between a ground line and a connection path from the common node to the antenna node;
wherein one end of the inductor is connected to the common node, the other end of the inductor is connected to one end of the capacitor and the antenna node, and the other end of the capacitor is grounded.
5. The multiplexer of claim 1, wherein an imaginary component of the parallel impedance of the transmit filter and the receive filter is negative.
6. The multiplexer of claim 5, wherein the reflection coefficient phase is between 180 degrees and 360 degrees.
7. The multiplexer of claim 6, wherein the reflection coefficient phase is between 270 degrees and 360 degrees.
8. The multiplexer of any one of claims 1 to 7, wherein each series resonant cell in the transmit filter is connected in series between the input node of the transmit filter and the common node; each series resonant cell in the receive filter is connected in series between an output node of the receive filter and the common node.
9. The multiplexer of claim 8, wherein the parallel resonant unit is connected in parallel between a connection node and a ground node, the connection node being a node on a connection path of two adjacent series resonant units.
10. The multiplexer of any one of claims 1 to 7, wherein the series resonant element and/or the parallel resonant element comprises an integral acoustic resonator.
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