A duplexer, a multiplexer, a high-frequency front-end circuit and a communication device

Abstract

The present invention provides a duplexer, a multiplexer, a high-frequency front-end circuit and a communication device, wherein the duplexer or multiplexer comprises a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal, and by setting the position of the resonator frequency, the roll-off of the transition band can be effectively improved in the multiplexer; at the same time, due to the impedance characteristics of the FBAR resonator itself, the out-of-band suppression will be deteriorated near the roll-off edge, and by using a plurality of resonators with different frequencies and electromechanical coupling coefficients, additional out-of-band zero points can be formed, thereby effectively improving the out-of-band suppression.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a duplexer, a multiplexer, a high-frequency front-end circuit and a communication device. Background Art

[0002] Broadband filters or duplexers and multiplexers are generally implemented using LC filters, which can achieve a bandwidth of several GHz. LTCC is widely used in LC filters due to its many advantages. However, due to the limitation of Q value, it has a greater disadvantage in insertion loss, out-of-band suppression and roll-off compared to FBAR. FBAR has a higher Q value and can achieve better insertion loss, out-of-band suppression, roll-off and other performance. However, due to the limitation of electromechanical coupling coefficient, it is difficult to achieve a wider bandwidth. Therefore, combining the broadband characteristics of LTCC and the high Q value characteristics of FBAR can achieve a better performance filter.

[0003] However, FBAR has a more complex impedance characteristic. In the impedance curve, the impedance is lower at the Fs frequency and higher at the Fp frequency. Therefore, in the process of combining FBAR and LTCC, especially in duplexers or multiplexers, it is a problem that needs to be solved to ensure that the area between Fs and Fp is used to form the fast roll-off edge of the filter without affecting other branches of the multiplexer. In addition, by using resonators with different frequencies and electromechanical coupling coefficients, multiple transmission zeros can be formed outside the band to form better suppression characteristics. Summary of the invention

[0004] In view of this, the present invention provides a multiplexer combining LTCC and FBAR, and by setting the position of the resonator frequency and the electromechanical coupling coefficient, the roll-off of the transition band in the multiplexer can be effectively improved; at the same time, due to the impedance characteristics of the FBAR itself, the out-of-band suppression will be deteriorated near the roll-off edge. By using multiple resonators with different frequencies and electromechanical coupling coefficients, additional out-of-band zero points can be formed, effectively improving the out-of-band suppression.

[0005] One aspect of the present invention provides a technical solution of a duplexer:

[0006] A duplexer includes a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal.

[0007] The transmitting side filter comprises:

[0008] at least one LC resonance unit connected between the input terminal and the antenna terminal; and

[0009] a resonator connected between the input terminal and the reference terminal; and

[0010] a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one LC resonance unit and a reference terminal;

[0011] The receiving side filter comprises:

[0012] at least two LC resonance units connected in series between the antenna terminal and the output terminal; and

[0013] a resonator connected between the output terminal and the reference terminal; and

[0014] The capacitor is connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and the reference terminal.

[0015] Another aspect of the present invention provides a technical solution of a duplexer:

[0016] A duplexer includes a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal.

[0017] The transmitting side filter comprises:

[0018] at least one LC resonance unit connected between the input terminal and the antenna terminal; and

[0019] a resonator group connected between the input terminal and the reference terminal; and

[0020] a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one LC resonance unit and a reference terminal;

[0021] The receiving side filter comprises:

[0022] at least two LC resonance units connected in series between the antenna terminal and the output terminal; and

[0023] a resonator group connected between the output terminal and the reference terminal; and

[0024] The capacitor is connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and the reference terminal.

[0025] Another aspect of the present invention provides a technical solution of a duplexer:

[0026] A duplexer includes a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal.

[0027] The transmitting side filter comprises:

[0028] at least one first resonator connected between the input terminal and the antenna terminal; and

[0029] A second resonator connected between the input terminal and the reference terminal; and

[0030] a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one first resonator and a reference terminal;

[0031] The receiving side filter comprises:

[0032] at least one LC resonance unit and a first resonator connected in series between the antenna terminal and the output terminal; and

[0033] A second resonator connected between the output terminal and the reference terminal; and

[0034] The capacitor is connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and the reference terminal.

[0035] Another aspect of the present invention provides a technical solution of a multiplexer:

[0036] A multiplexer includes a plurality of the transmitting side filters and receiving side filters as described above, wherein the plurality of transmitting side filters and receiving side filters are connected in common and to an antenna terminal.

[0037] One aspect of the present invention provides a technical solution of a high-frequency front-end circuit:

[0038] A high frequency front end circuit, comprising:

[0039] A duplexer or multiplexer; and

[0040] An amplifier circuit connected to the duplexer or the multiplexer.

[0041] Another aspect of the present invention provides a technical solution of a communication device:

[0042] A communication device, comprising:

[0043] an RF signal processing circuit for processing high frequency signals transmitted and received by the antenna element; and

[0044] A high frequency front end circuit transmits the high frequency signal between the antenna element and the RF signal processing circuit.

[0045] The beneficial effects achieved by the present invention are:

[0046] (1) The present invention determines the position of the FBAR resonator in the LC filter topology, which is generally located far away from the antenna end, and uses the resonator to replace the original capacitor to achieve high roll-off;

[0047] (2) The present invention determines the position of the frequency of the FBAR resonator and the setting of the Fs and Fp frequencies, ensuring that other frequency bands are not affected and improving the roll-off edge of the transition band;

[0048] (3) The present invention introduces FBAR resonators to improve roll-off, but will deteriorate out-of-band suppression at specific locations. By adding additional resonators, additional transmission zeros are formed. The added additional resonators have different frequencies and electromechanical coupling coefficients, which will improve out-of-band suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings are used to better understand the present invention and do not constitute an improper limitation of the present invention.

[0050] Figure 1 It is a schematic diagram of the topological structure of an existing LC duplexer;

[0051] Figure 2 is a schematic diagram of the topological structure of a duplexer in Embodiment 1;

[0052] Figure 3 This is a comparison diagram of the duplexer curves using a combination of FBAR and LTCC;

[0053] Figure 4 yes Figure 3 A zoomed in picture of the 2.4-3.6GHz frequency region;

[0054] Figure 5 It is a schematic diagram of the location of the resonator impedance curve where the curve of the duplexer is located;

[0055] Figure 6 This is the corresponding curve diagram when the Fs of the left resonator is close to 2.69GHz;

[0056] Figure 7 This is the corresponding curve diagram when the Fp of the right resonator is close to 3.3GHz;

[0057] Figure 8 This is the schematic diagram of the equivalent capacitance corresponding to the resonator;

[0058] Fig. 9 is a schematic diagram of the topological structure of the duplexer of Embodiment 2;

[0059] Fig.10 is a schematic diagram of the topological structure of the duplexer of Embodiment 3;

[0060] Fig.11 This is a diagram showing the effect of the duplexer of the third embodiment. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0062] Figure 1 1 is a circuit diagram of an existing duplexer 1. Figure 1 As shown, the duplexer 1 includes a transmission-side filter 11 , a reception-side filter 12 , and an antenna terminal 13 .

[0063] The transmission filter 11 receives a transmission wave generated by a transmission circuit through a transmission input terminal 14, filters the transmission wave in a transmission passband, and outputs the transmitted wave to an antenna terminal 13, which is a transmission output terminal. More specifically, the transmission filter 11 includes an LC resonance unit 111, capacitors 112 to 113, matching inductance elements 114 to 117, and a transmission input terminal 14.

[0064] The LC resonance unit 111 is connected between the transmission input terminal 14 and the antenna terminal 13; the capacitors 112 to 113 are connected in parallel with each other between the transmission input terminal 14 and the antenna terminal 13 and the reference terminal (ground); the inductor element 114 is connected between the transmission input terminal 14 and the LC resonance unit 111; the inductor element 115 is connected between the antenna terminal 13 and the LC resonance unit 111; the inductor element 116 is connected between the connection point of the capacitor 112 and the reference terminal (ground); and the inductor element 117 is connected between the connection point of the capacitor 113 and the reference terminal (ground).

[0065] The receiving side filter inputs a reception wave input from the antenna terminal 13 which also serves as a receiving side input terminal, filters the reception wave in a reception passband, and outputs the reception wave to the receiving output terminal 15. More specifically, the receiving side filter 12 includes LC resonance units 121 to 122, capacitors 123 to 125, matching inductance elements 126 to 1211, matching capacitance elements 1212 to 1213, and the receiving output terminal 15.

[0066] The LC resonance units 121 to 122 are connected in series with each other between the antenna terminal 13 and the reception output terminal 15; the capacitors 123 to 125 are connected in parallel with each other between the antenna terminal 13, the reception output terminal 15, and the connection points of the LC resonance units 121 to 122 and the reference terminal (ground); the inductor element 126 and the capacitor element 129 are connected in series between the antenna terminal 13 and the LC resonance unit 121; the inductor element 127 and the capacitor element 1210 are connected in series between the LC resonance unit 121 and the LC resonance unit 122; the inductor element 128 is connected between the LC resonance unit 122 and the reception output terminal 15; the inductor element 129 is connected between the connection point of the capacitor 123 and the reference terminal (ground); the inductor element 1210 is connected between the connection point of the capacitor 124 and the reference terminal (ground); and the inductor element 1211 is connected between the connection point of the capacitor 125 and the reference terminal (ground).

[0067] In this embodiment, the LC resonance unit can be implemented by LTCC, discrete devices, IPD or other forms. LTCC is widely used in LC resonance units due to its various advantages.

[0068] Embodiment 1

[0069] Figure 2 FIG. 2 is a circuit diagram of the duplexer 2 according to the embodiment. Figure 2 As shown, the duplexer 2 includes a transmission-side filter 21 , a reception-side filter 22 , and an antenna terminal 23 .

[0070] The transmission filter 21 receives a transmission wave generated by a transmission circuit through a transmission input terminal 24, filters the transmission wave in a transmission passband, and outputs the transmitted wave to an antenna terminal 23, which is a transmission output terminal. More specifically, the transmission filter 21 includes an LC resonance unit 211, a resonator 212, a capacitor 213, matching inductance elements 214 to 217, and a transmission input terminal 24.

[0071] The LC resonance unit 211 is connected between the transmission input terminal 24 and the antenna terminal 23; the resonator 212 is connected between the transmission input terminal 24 and the reference terminal (ground), and the capacitor 213 is connected between the antenna terminal 23 and the reference terminal (ground); the inductor element 214 is connected between the transmission input terminal 24 and the LC resonance unit 211, and the inductor element 215 is connected between the antenna terminal 23 and the LC resonance unit 211; the inductor element 216 is connected between the connection point of the resonator 212 and the reference terminal (ground); and the inductor element 217 is connected between the connection point of the capacitor 213 and the reference terminal (ground).

[0072] The receiving side filter inputs a reception wave input from the antenna terminal 23 which also serves as a receiving side input terminal, filters the reception wave in a reception passband, and outputs the reception wave to the receiving output terminal 25. More specifically, the receiving side filter 22 includes LC resonance units 221-222, capacitors 223-224, a resonator 225, matching inductance elements 226-2211, matching capacitance elements 2212-2213, and the receiving output terminal 25.

[0073] The LC resonance units 221 to 222 are connected in series with each other between the antenna terminal 23 and the reception output terminal 25; the capacitors 223 to 224 are connected in parallel with each other between the connection point of the antenna terminal 23 and the LC resonance units 221 to 222 and the reference terminal (ground), and the resonator 225 is connected between the reception output terminal 25 and the reference terminal (ground); the inductor element 226 and the capacitor element 2212 are connected in series between the antenna terminal 23 and the LC resonance unit 221; the inductor element 227 and the capacitor element 2213 are connected in series between the LC resonance unit 221 and the LC resonance unit 222, and the inductor element 228 is connected between the LC resonance unit 222 and the reception output terminal 25; the inductor element 229 is connected between the connection point of the capacitor 223 and the reference terminal (ground); the inductor element 2210 is connected between the connection point of the capacitor 224 and the reference terminal (ground); and the inductor element 2211 is connected between the connection point of the resonator 225 and the reference terminal (ground).

[0074] In this embodiment, resonator 212 and resonator 225 are FBAR resonators, and FBAR resonators are used to replace the capacitors in the figure to improve the roll-off edge, where the resonator at the dotted line is the replaced resonator, and the corresponding capacitor needs to be removed. The position of the resonator is generally far away from the antenna, because changes in components close to the antenna end have an impact on the matching of the common end, and the impact is relatively large. At a position far away from the antenna end, the impact of replacing the capacitor is relatively small.

[0075] Figure 3 This is a comparison of the duplexer curves using a combination of FBAR and LTCC. The solid line is with an FBAR resonator, and the dotted line is a single LTCC duplexer. It can be seen that the introduction of FBAR has greatly improved the roll-off characteristics, where roll-off is defined as the frequency required from -3dB insertion loss to a certain depth of out-of-band suppression, such as -30dB. The smaller the frequency, the better the roll-off.

[0076] Figure 4 yes Figure 3 A magnified schematic diagram of the 2.4-3.6 GHz frequency region, where the solid line is the FBAR resonator and the dotted line is the LTCC duplexer alone.

[0077] Figure 5 It is the position of the resonator impedance curve in the duplexer curve, where the two black thick lines correspond to the Y-axis coordinates on the right, representing the impedance curve that changes with frequency. The right edge of the passband of the left filter of the above duplexer is 2.69GHz, and the left edge of the passband of the right filter is 3.3GHz. The Fs of the left resonator needs to be greater than 2.69GHz, and the Fp of the right resonator needs to be less than 3.3GHz, and the farther away the better.

[0078] Figure 6 When the Fs of the resonator on the left is close to 2.69GHz, the corresponding curve shows that a notch is formed near the passband, which seriously deteriorates the insertion loss.

[0079] Figure 7 This is the corresponding curve when the Fp of the resonator on the right is close to 3.3GHz. It can be seen that a notch is formed near the passband, which seriously deteriorates the insertion loss.

[0080] Figure 8 It is the equivalent capacitance corresponding to the resonator. It can be seen that near the resonant frequency of the resonator, there will be a rapid impedance transformation, resulting in a large impedance change. Therefore, when it is located in the passband, the passband matching will be seriously deteriorated. At a position far away from the resonant frequency, it is a fixed capacitor. Using this capacitor to be equivalent to the capacitor in the LC resonant unit in the design can reduce the impact on the passband.

[0081] Embodiment 2

[0082] Fig. 9 FIG. 1 is a circuit diagram of the duplexer 3 according to the embodiment. Fig. 9 As shown, the duplexer 3 includes a transmission-side filter 31 , a reception-side filter 32 , and an antenna terminal 33 .

[0083] The transmission filter 31 receives a transmission wave generated by a transmission circuit through a transmission input terminal 34, filters the transmission wave in a transmission passband, and outputs the transmitted wave to an antenna terminal 33, which is a transmission output terminal. More specifically, the transmission filter 31 includes an LC resonance unit 311, resonators 312 to 313, a capacitor 314, matching inductance elements 315 to 318, and a transmission input terminal 34.

[0084] The LC resonance unit 311 is connected between the transmission input terminal 34 and the antenna terminal 33; the resonators 312 to 313 are connected in parallel with each other between the transmission input terminal 34 and the reference terminal (ground), and the capacitor 314 is connected between the antenna terminal 33 and the reference terminal (ground); the inductor element 315 is connected between the transmission input terminal 34 and the LC resonance unit 311, and the inductor element 316 is connected between the antenna terminal 33 and the LC resonance unit 311; the inductor element 317 is connected between the connection point of the resonators 312 to 313 and the reference terminal (ground); and the inductor element 318 is connected between the capacitor 314 and the reference terminal (ground).

[0085] Alternatively, the resonators 312 to 313 are connected in series with each other between the transmission input terminal 34 and the reference terminal (ground).

[0086] The receiving side filter inputs a reception wave input from the antenna terminal 33 which also serves as a receiving side input terminal, filters the reception wave in a reception passband, and outputs the reception wave to the receiving output terminal 35. More specifically, the receiving side filter 32 includes LC resonance units 321 to 322, capacitors 323 to 324, resonators 325 to 326, matching inductance elements 327 to 3212, matching capacitance elements 3213 to 3214, and the receiving output terminal 35.

[0087] The LC resonant units 321-322 are connected in series with each other between the antenna terminal 33 and the receiving output terminal 35; the capacitors 323-324 are connected in parallel with each other between the connection point of the antenna terminal 33 and the LC resonant units 321-322 and the reference terminal (ground), and the resonators 325-326 are connected in parallel with each other between the receiving output terminal 35 and the reference terminal (ground); the inductor element 327 and the capacitor element 3213 are connected in series between the antenna terminal 33 and the LC resonant unit 321; the inductor element 323-324 is connected in parallel with each other between the antenna terminal 33 and the LC resonant unit 321; 28 and capacitor element 3214 are connected in series between the LC resonance unit 321 and the LC resonance unit 322, and the inductor element 329 is connected between the LC resonance unit 322 and the receiving output terminal 35; the inductor element 3210 is connected between the connection point of the capacitor 323 and the reference terminal (ground); the inductor element 3211 is connected between the connection point of the capacitor 324 and the reference terminal (ground); and the inductor element 3212 is connected between the connection point of the resonators 325~326 and the reference terminal (ground).

[0088] Alternatively, the resonators 325 to 326 are connected in series with each other between the reception output terminal 35 and the reference terminal (ground).

[0089] In this embodiment, resonators 312-313 and resonators 325-326 are FBAR resonators, and FBAR resonators are used to replace the capacitors in the figure to improve the roll-off edge. The resonator at the dotted line is the replaced resonator, and the corresponding capacitor needs to be removed. The position of the resonator is generally far away from the antenna, because changes in components close to the antenna end have an impact on the matching of the common end, and the impact is relatively large. At a position far away from the antenna end, the impact of replacing the capacitor is relatively small.

[0090] from Figure 3 It can be seen that the roll-off of the duplexer of this embodiment is improved by adding the FBAR resonator, but the out-of-band suppression deteriorates in some areas outside the band. Fig. 9 The out-of-band suppression is improved by connecting a resonator of different frequency or kt in parallel (or in series) with the original resonator.

[0091] Embodiment 3

[0092] Fig.10 FIG. 4 is a circuit diagram of the duplexer 4 according to the embodiment. Fig.10 As shown, the duplexer 4 includes a transmission-side filter 41 , a reception-side filter 42 , and an antenna terminal 43 .

[0093] The transmission filter 41 receives a transmission wave generated by a transmission circuit through a transmission input terminal 44, filters the transmission wave in a transmission passband, and outputs the transmitted wave to an antenna terminal 43, which is a transmission output terminal. More specifically, the transmission filter 41 includes resonators 411 to 412, a capacitor 413, matching inductors 414 to 418, and a transmission input terminal 44.

[0094] Resonator 411 is connected between the transmit input terminal 44 and the antenna terminal 43, resonator 412 is connected between the transmit input terminal 44 and the reference terminal (ground), capacitor 413 is connected between the antenna terminal 43 and the reference terminal (ground), inductor element 414 is connected between the transmit input terminal 44 and the LC resonance unit 411, inductor element 415 is connected to both ends of the resonator 411, inductor element 416 is connected between the antenna terminal 43 and the LC resonance unit 311; inductor element 417 is connected between the connection point of resonator 412 and the reference terminal (ground); inductor element 418 is connected between the connection point of capacitor 413 and the reference terminal (ground).

[0095] The receiving side filter inputs a reception wave input from the antenna terminal 43 which also serves as a receiving side input terminal, filters the reception wave in a reception passband, and outputs the reception wave to the receiving output terminal 45. More specifically, the receiving side filter 42 includes an LC resonance unit 421, a resonator 422, capacitors 423 to 424, a resonator 425, matching inductance elements 426 to 4212, matching capacitance elements 4213 to 4214, and the receiving output terminal 45.

[0096] The LC resonance unit 421 and the resonator 422 are connected in series between the antenna terminal 43 and the receiving output terminal 45; the capacitors 423-424 and the resonator 425 are connected in parallel between the connection point of the antenna terminal 43, the receiving output terminal 45, the LC resonance unit 421 and the resonator 422 and the reference terminal (ground); the inductor element 426 and the capacitor element 4213 are connected in series between the antenna terminal 43 and the LC resonance unit 421; the inductor element 427 and the capacitor element 4214 are connected in series. The inductor element 428 is connected between the LC resonance unit 421 and the resonator 422, the inductor element 428 is connected in parallel at both ends of the resonator 422, and the inductor element 429 is connected between the resonator 422 and the receiving output terminal 45; the inductor element 4210 is connected between the connection point of the capacitor 423 and the reference terminal (ground); the inductor element 4211 is connected between the connection point of the capacitor 424 and the reference terminal (ground); and the inductor element 4212 is connected between the connection point of the resonator 425 and the reference terminal (ground).

[0097] from Fig.10 It can be seen that the resonator that changes the frequency and electromechanical coupling coefficient can also be a resonator that replaces the capacitor in other positions.

[0098] Fig.11 This is the effect achieved by the duplexer involved in this embodiment. The suppression at 2.7-2.8 GHz is improved from the original 25 to the current 30 dB.

[0099] Embodiment 4

[0100] This embodiment provides a multiplexer, which includes multiple transmitting side filters, receiving side filters and antenna terminals, one end of the multiple transmitting side filters is respectively connected to the antenna terminal, and one end of the receiving side filter is also connected to the antenna terminal.

[0101] In the present application, the structures of the transmitting side filter and the receiving side filter are as described in the above embodiments and will not be described in detail in the present application.

[0102] Embodiment 5

[0103] Here, a high-frequency front-end circuit and a communication device including the duplexer according to the above-mentioned embodiment will be described.

[0104] The high-frequency front-end circuit, the RF signal processing circuit and the baseband signal processing circuit constitute a communication device.

[0105] The high-frequency front-end circuit includes a duplexer, a power amplifier circuit and a low-noise amplifier circuit.

[0106] The power amplifier circuit is a transmission amplifier circuit that amplifies the high-frequency transmission signal output from the RF signal processing circuit and outputs the amplified signal to the antenna element via the transmission input terminal, the transmission filter, and the antenna terminal.

[0107] The low noise amplifier circuit is a reception amplifier circuit that amplifies a high frequency signal obtained via an antenna element, an antenna terminal, and a transmission filter, and outputs the amplified signal to an RF signal processing circuit.

[0108] The RF signal processing circuit performs signal processing on the high-frequency reception signal input from the antenna element via the reception signal path by down-conversion, etc., and outputs the reception signal generated by the signal processing to the baseband signal processing circuit. In addition, the RF signal processing circuit 3 performs signal processing on the transmission signal input from the baseband signal processing circuit by up-conversion, etc., and outputs the high-frequency transmission signal generated by the signal processing to the power amplifier circuit. The RF signal processing circuit 3 is, for example, an RFIC (Radio Frequency Integrated Circuit).

[0109] The signal processed by the baseband signal processing circuit is used, for example, as an image signal for image display or as an audio signal for telephone calls.

[0110] In addition, the high-frequency front-end circuit may include other circuit elements between the duplexer, the power amplifier circuit, and the low-noise amplifier circuit.

[0111] In addition, the above description uses a duplexer as an example, but the present invention can also be applied to a triplexer in which antenna terminals of three filters are shared, or a quadplexer in which antenna terminals of four filters are shared. In other words, the high-frequency front-end circuit and the communication device only need to have two or more filters.

[0112] Furthermore, the high-frequency front-end circuit and the communication device are not limited to the configuration including both the transmission filter and the reception filter, and may include only the transmission filter or only the reception filter.

[0113] Furthermore, the communication device may include a baseband signal processing circuit according to a method of processing high-frequency signals.

[0114] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A duplexer, comprising a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal, characterized in that: The transmitting side filter comprises: At least one LC resonance unit connected between the input terminal and the antenna terminal; and a first inductor, a first resonator, and a second inductor, wherein: A first end of the first inductor is connected to the input terminal, and a second end of the first inductor is connected to the first end of the first resonator; A second inductor is connected between the second end of the first resonator and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one LC resonance unit and a reference terminal; The receiving side filter comprises: At least two LC resonant units connected in series between the antenna terminal and the output terminal; and a third inductor, a second resonator, and a fourth inductor, wherein: A first end of the third inductor is connected to the output terminal, and a second end of the third inductor is connected to the first end of the second resonator; A fourth inductor is connected between the second end of the second resonator and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and a reference terminal; The LC resonance unit is implemented by LTCC, and the resonator is a FBAR resonator.

2. The duplexer according to claim 1, characterized in that: Also includes: Matching elements are connected between the input terminal and the LC resonance unit, between the antenna terminal and the LC resonance unit, between the capacitor and the reference terminal, and between the connection point of the resonator and the reference terminal.

3. A duplexer, comprising a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal, characterized in that: The transmitting side filter comprises: At least one LC resonance unit is connected between the input terminal and the antenna terminal; and a first resonator group and a second inductor are formed by connecting in series or in parallel a first inductor, a plurality of resonators with different frequencies or electromechanical coupling coefficients, wherein: A first end of the first inductor is connected to the input terminal, and a second end of the first inductor is connected to the first end of the first resonator group; A second inductor is connected between the second end of the first resonator group and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one LC resonance unit and a reference terminal; The receiving side filter comprises: At least two LC resonant units are connected in series between the antenna terminal and the output terminal; and a third inductor, a second resonator group composed of a plurality of resonators with different frequencies or electromechanical coupling coefficients connected in series or in parallel, and a fourth inductor, wherein: A first end of the third inductor is connected to the output terminal, and a second end of the third inductor is connected to the first end of the second resonator group; A fourth inductor is connected between the second end of the second resonator group and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and a reference terminal; The LC resonance unit is implemented by LTCC, and the resonator is a FBAR resonator.

4. A duplexer, comprising a transmitting side filter and a receiving side filter, wherein the transmitting side filter and the receiving side filter are connected together and connected to an antenna terminal, characterized in that: The transmitting side filter comprises: at least one first resonator connected between the input terminal and the antenna terminal and in parallel with the inductor; and a first inductor, a second resonator, a second inductor, wherein: A first end of the first inductor is connected to the input terminal, and a second end of the first inductor is connected to the first end of the second resonator; A second inductor is connected between the second end of the second resonator and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least one first resonator and a reference terminal; The receiving side filter comprises: at least one LC resonance unit and a third resonator connected in series between the antenna terminal and the output terminal, the third resonator being connected in parallel with the inductor; and a third inductor, a fourth resonator, and a fourth inductor, wherein: A first end of the third inductor is connected to the output terminal, and a second end of the third inductor is connected to the first end of the fourth resonator; A fourth inductor is connected between the second end of the fourth resonator and the reference terminal; and a capacitor connected between the antenna terminal and any one of the connection nodes of the at least two LC resonance units and a reference terminal; The LC resonance unit is implemented by LTCC, and the resonator is a FBAR resonator.

5. The duplexer according to claim 4, characterized in that: Also includes: A matching element is connected between the input terminal and the first resonator, between the antenna terminal and the first resonator, between the capacitor and the reference terminal, and between the connection point of the second resonator and the reference terminal.

6. The duplexer according to claim 4, characterized in that: The first resonator and the second resonator are FBAR resonators respectively.

7. A multiplexer, characterized in that: The invention comprises a plurality of the transmission side filters and the reception side filters according to any one of claims 1 to 6, wherein the plurality of transmission side filters and the reception side filters are connected in common and connected to an antenna terminal.

8. A high frequency front end circuit, characterized in that: include: The duplexer according to any one of claims 1 to 6 or the multiplexer according to claim 7; and An amplifier circuit connected to the duplexer or the multiplexer.

9. A communication device, characterized in that: include: RF signal processing circuit for processing high frequency signals transmitted and received by the antenna element; and The high frequency front end circuit according to claim 8 transmits the high frequency signal between the antenna element and the RF signal processing circuit.

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