Low-pass and band-pass duplexer based on LTCC process
Technical Field
The utility model relates to a low-pass and band-pass duplexer based on an LTCC process, and belongs to the technical field of duplexers.
Background
The duplexer is a microwave device widely used in radio receivers, can realize the combination of two different frequency signals or the division of a single broadband signal into two frequency band signals, has the functions of isolating transmitting and receiving signals and ensuring that both receiving and transmitting can work normally at the same time, and is widely used in the fields of mobile communication, electronic countermeasure and the like. The technical indexes of the duplexer mainly comprise: the duplexer has the advantages of working frequency band, in-band insertion loss, in-band return loss, out-of-band rejection, output end isolation and the like, and the temperature stability, the volume, the weight and the like of the duplexer are important indexes for measuring the performance of the duplexer.
With the high-speed development of wireless communication technology, communication systems develop towards high performance, high reliability and miniaturization, a duplexer is required to be small in size and light in weight, and a filter in the duplexer is required to be wide in working frequency band, good in filter characteristic and high in common mode rejection, but the size of the duplexer in the prior art cannot meet the size requirement of wireless communication more and more; according to different used frequency bands, duplexers mainly comprise a low-pass duplexer, a high-pass duplexer, a low-pass duplexer, a band-pass duplexer and a band-pass duplexer, a parasitic pass band exists in a low-frequency part in the design of a traditional duplexer, the out-of-band rejection capability of a high-frequency part is poor, and therefore the isolation degree and the out-of-band rejection degree between output ports cannot meet the requirements of a microwave millimeter wave circuit in a small size.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects of the existing duplexer, provides a low-pass and band-pass duplexer based on an LTCC (low temperature co-fired ceramic) process, realizes the balance of the duplexer in volume and performance, and has good frequency selection characteristic and isolation characteristic.
The utility model is realized by adopting the following technical scheme:
the utility model provides a low pass and band-pass duplexer based on LTCC technology, including LTCC base member layer, LTCC base member layer forms there is the duplexer circuit structure, duplexer circuit structure comprises low pass filter circuit and band-pass filter circuit, low pass filter circuit is including establishing ties first inductance and the second inductance between sharing input port and low frequency output port, be connected with the first electric capacity of ground connection between first inductance and the second inductance, band-pass filter circuit is including establishing ties first series resonator and the second series resonator between sharing input port and high frequency output port, be connected with the third series resonator between first series resonator and the second series resonator, the third series resonator is connected with the first parallel resonator of ground connection.
Further, the inductors of the low-pass filter circuit and the band-pass filter circuit are laminated inductors, metal conductors on different circuit layers are connected through holes, and the inductance value is adjusted by adjusting the line length and the line width of each layer of the laminated inductor line.
Further, the capacitors of the low-pass filter circuit and the band-pass filter circuit are MIM capacitors formed between upper and lower plates.
Furthermore, ten circuit layers are arranged in the LTCC substrate layer, a first inductor and a second inductor of the low-pass filter circuit are formed on the first layer, the second layer and the third layer, a first capacitor is formed on the fourth layer and the fifth layer, a third series resonator and a first parallel resonator of the band-pass filter circuit are formed on the sixth layer and the seventh layer, and a first series resonator and a second series resonator of the band-pass filter circuit are formed on the eighth layer, the ninth layer and the tenth layer.
Furthermore, the first inductor is connected with the common input port through an inductor wire of a third layer, the second inductor is connected with the low-frequency output port through an inductor wire of a third layer, a connecting wire is arranged between the first inductor and the second inductor, a connecting through hole is formed in the connecting wire, the first inductor and the second inductor are connected with an upper-level plate of the first capacitor through the connecting through hole, a lower-level plate of the first capacitor is connected with the ground port, the first series resonator is connected with the common input port through an inductor wire of an eighth layer, the second series resonator is connected with the high-frequency output port through an inductor wire of an eighth layer, the first series resonator, the second series resonator, the third series resonator and the first parallel resonator are connected through the connecting through hole, and the first parallel resonator is connected with the ground port through a connecting wire of a sixth layer.
The utility model has the beneficial effects that:
according to the utility model, through reasonable three-dimensional layout, parasitic pass band suppression on the low-pass duplexer and optimization of out-of-band suppression effect of the high-pass duplexer are realized by using parasitic parameters of all elements, balance of the duplexer on volume and performance is realized, and meanwhile, the isolation degree of the low-pass signal output end and the band-pass signal output end is effectively increased by adding the isolation metal layer, the size of the duplexer is reduced, the frequency division function of low-frequency low-pass signals and high-frequency band-pass signals is realized, and the duplexer has good frequency selection characteristic and isolation characteristic.
Drawings
FIG. 1 is an equivalent circuit diagram of the present invention;
FIG. 2 is a schematic structural view of the present invention;
FIG. 3 is a schematic circuit diagram of the present invention in isolation;
FIG. 4 is the S parameter simulation result of the present invention;
FIG. 5 isolation simulation results of the present invention.
The labels in the figure are: 1. an LTCC substrate layer; 2. a low-pass filter circuit; 3. a band-pass filter circuit; 4. and isolating the metal layer.
Detailed Description
The utility model will be further explained with reference to the drawings.
As shown in fig. 1, in the equivalent circuit diagram of the present invention, the duplexer circuit structure is composed of a low-pass filter circuit and a band-pass filter circuit, the low-pass filter circuit includes a first inductor and a second inductor connected in series between a common input port and a low-frequency output port, a first capacitor connected to ground is connected between the first inductor and the second inductor, the band-pass filter circuit includes a first series resonator and a second series resonator connected in series between the common input port and a high-frequency output port, a third series resonator is connected between the first series resonator and the second series resonator, and the third series resonator is connected to a first parallel resonator connected to ground.
As shown in fig. 2, the utility model includes an LTCC substrate layer 1 sintered by a laminated low-temperature co-fired ceramic process, a first ground terminal G1, a common input terminal P1, a second ground terminal G2, a low-frequency signal output terminal P2, a third ground terminal G3, a high-frequency signal output terminal P3 on the outer wall of the LTCC substrate layer 1, a low-pass filter circuit 2, a band-pass filter circuit 3, and an isolation metal layer 4 for isolating low-pass signals and band-pass signals inside the LTCC substrate layer; the typical dimensions of the utility model are 2.0X 1.25X 0.59 mm.
As shown in fig. 3, the LTCC substrate layer 1 of the present invention comprises ten circuit layers, wherein: a first layer, wherein an inductor (1-L1) and an inductor (1-L2) are printed on a ceramic medium, the inductor (1-L1) and the inductor (1-L2) are connected through a connecting wire, a through hole (1-V3) is connected between the inductor (1-L1) and the inductor (1-L2), the other end of the inductor (1-L1) is connected with the inductor (1-V1), and the other end of the inductor (1-L2) is connected with the inductor (1-V2); the second layer is characterized in that an inductor (2-L1) and an inductor (2-L2) are printed on the ceramic dielectric, one end of the inductor (2-L1) is connected with a through hole (1-V1), the other end of the inductor is connected with a through hole (2-V1), one end of the inductor (2-L2) is connected with the through hole (1-V2), the other end of the inductor is connected with a through hole (2-V2), and the through hole (1-V3) is connected with the through hole (2-V3); a third layer, wherein an inductor (3-L1) and an inductor (3-L2) are printed on the ceramic dielectric, one end of the inductor (3-L1) is connected with a through hole (2-V1), the other end of the inductor is connected with a common input end P1, one end of the inductor (3-L2) is connected with the through hole (2-V2), the other end of the inductor is connected with a low-frequency signal output end P2, and the through hole (2-V3) is connected with the through hole (3-V3); a fourth layer, capacitors (4-C1) are printed on the ceramic dielectric, and the capacitors (4-C1) are connected with the through holes (3-V5); fifth layer, printing a capacitor (5-C1) on the ceramic dielectric as the large ground for isolating the low-pass filter circuit and the band-pass filter circuit, wherein the capacitor (5-C1) is connected with the ports G1, G2 and G3; a sixth layer, wherein an inductor 6-L5, an inductor 6-L6, a capacitor 6-C5 and a capacitor 6-C6 are printed on the ceramic dielectric, one end of the inductor 6-L5 is connected with the capacitor 6-C5, the other end of the inductor 6-L5 is connected with a through hole 6-V5, one end of the inductor 6-L6 is connected with the capacitor 6-C6, the other end of the inductor 6-L3528 is connected with the through hole 6-V6, and the inductor 6-L6 and the capacitor 6-C6 are connected with a ground port G3 through a connecting wire; a seventh layer, wherein an inductor 7-L5, an inductor 7-L6, a capacitor 7-C5 and a capacitor 7-C6 are printed on the ceramic dielectric, wherein the capacitor 7-C5 is connected with a through hole 7-V4, one end of the inductor 7-L5 is connected with a through hole 6-V5, the other end of the inductor 7-L5 is connected with the capacitor 7-C6, the capacitor 7-C6 is connected with the inductor 7-L6, and the other end of the inductor 7-L6 is connected with a through hole 6-V6; an eighth layer, wherein an inductor 8-L3 and an inductor 8-L4 are printed on the ceramic dielectric, one end of the inductor 8-L3 is connected with 8-V7, the other end of the inductor 8-L3 is connected with a high-frequency output port P3, one end of the inductor 8-L4 is connected with 8-V8, the other end of the inductor 8-L4 is connected with a common input port P1, and a through hole 8-V4 is connected with a through hole 7-V4; a ninth layer, wherein an inductor 9-L3, an inductor 9-L4, a capacitor 9-C3 and a capacitor 9-C4 are printed on the ceramic dielectric, one end of the inductor 9-L3 is connected with a through hole 8-V7, the other end of the inductor 9-L3 is connected with a through hole 9-V7, one end of the inductor 9-L3 is connected with the through hole 8-V8, the other end of the inductor 9-L3 is connected with a through hole 9-V8, the capacitor 9-C3 is connected with one end of the capacitor 9-C4, and a through hole 8-V4 is connected between the capacitor 9-C3 and the capacitor 9-C4; and a tenth layer, wherein an inductor 10-L3, an inductor 10-L4, a capacitor 10-C3 and a capacitor 10-C4 are printed on the ceramic dielectric, one end of the inductor 10-L3 is connected with a through hole 9-V7, the other end of the inductor 10-L3 is connected with the capacitor 10-C3, one end of the inductor 10-L4 is connected with the through hole 9-V8, and the other end of the inductor 10-L4 is connected with the capacitor 10-C5.
As shown in FIGS. 4-5, the low-frequency working frequency of the duplexer is DC-3.0 GHz, the high-frequency working frequency of the duplexer is 5.2 GHz-6.0 GHz, the insertion loss of the duplexer at low frequency is better than 0.8dB, the insertion loss of the duplexer at 5.2 GHz-6.0 GHz is better than the return loss of the duplexer in two wave bands of 1.2, the isolation between the two output ports is better than 20dB, the out-of-band rejection of the low-pass branch circuit at 4.6 GHz-15 GHz is better than 20dB, the out-of-band rejection of the band-pass branch circuit at DC-3.5 GHz is better than 20dB, and the out-of-band rejection of the band-pass branch circuit at 8.0 GHz-15 GHz is better than 20 dB.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the utility model as claimed. The scope of the utility model is defined by the appended claims and equivalents thereof.