CN114374369A

CN114374369A - Low temperature co-fired ceramic (LTCC) process-based duplexer with low-frequency transmission zero point

Info

Publication number: CN114374369A
Application number: CN202111495363.3A
Authority: CN
Inventors: 邢孟江; 代传相; 杨晓东; 邢孟道; 刘永红
Original assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Current assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2022-04-19

Abstract

The invention relates to a duplexer with a low-frequency transmission zero based on an LTCC process, belonging to the technical field of duplexers. The low-pass filter circuit comprises a low-temperature co-fired ceramic (LTCC) substrate layer, wherein a duplexer circuit structure is formed on the LTCC substrate layer and consists of a low-pass filter circuit and a band-pass filter circuit, the low-pass filter circuit comprises a first inductor and a first parallel resonator which are connected in series between a common input port and a low-frequency output port, a first capacitor which is grounded is connected between the first inductor and the first parallel resonator, the band-pass filter circuit comprises a first series resonator and a second series resonator which are 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 with a second parallel resonator which is grounded.

Description

Low temperature co-fired ceramic (LTCC) process-based duplexer with low-frequency transmission zero point

Technical Field

The invention relates to a duplexer with a low-frequency transmission zero based on an LTCC process, belonging 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 working frequency band, in-band insertion loss, in-band return loss, out-of-band rejection, output end isolation and the like, and in addition, 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 the directions of high performance, high reliability and miniaturization, the duplexer is required to be small in size and light in weight, and the filter in the duplexer is required to be wide in working frequency band, good in filter characteristic and high in common mode rejection degree, 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, the duplexer mainly comprises a low-pass duplexer, a high-pass duplexer, a low-pass duplexer, a band-pass duplexer and a band-pass duplexer, a parasitic passband exists in a low-frequency part in the design of the 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.

Disclosure of Invention

The invention aims to overcome the defects of the existing duplexer and provides a duplexer with a low-frequency transmission zero based on an LTCC process.

The invention is realized by adopting the following technical scheme:

the utility model provides a duplexer with low frequency transmission zero based on LTCC technology, including LTCC base member layer, LTCC base member layer forms there is 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 first parallel resonator between sharing input port and low frequency output port, be connected with the first electric capacity of ground connection between first inductance and the first parallel resonator, 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 second 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, the LTCC substrate layer is internally provided with eleven circuit layers, a first inductor of a low-pass filter circuit and an inductor of a first parallel resonator are formed on the first layer, the second layer and the third layer, a first capacitor is formed on the fifth layer and the sixth layer, a capacitor of the first parallel resonator is formed on the fourth layer and the fifth layer, a third series resonator and a first parallel resonator of a band-pass filter circuit are formed on the seventh layer and the eighth layer, and a first series resonator and a second series resonator of the band-pass filter circuit are formed on the ninth layer, the tenth layer and the eleventh layer.

Furthermore, the first inductor is connected with the common input port through an inductor wire of a third layer, the inductor of the first parallel resonator is connected with the low-frequency output port through an inductor wire of a third layer, the capacitor of the first parallel resonator is connected with the low-frequency output port at a fourth layer, 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 a ninth layer, the second series resonator is connected with the high-frequency output port through an inductor wire of a ninth layer, the first series resonator, the second series resonator, the third series resonator and the first parallel resonator are connected through connecting through holes, and the second parallel resonator is connected with the ground port through a connecting wire of a sixth layer.

The invention has the beneficial effects that:

the invention realizes the effects of restraining the parasitic passband on the low-pass duplexer and optimizing the out-of-band restraint of the high-pass duplexer by reasonable three-dimensional layout and utilizing the parasitic parameters of all elements, realizes the balance of the duplexer on the volume and the performance, and simultaneously increases the out-of-band restraint of the low-pass branch by introducing the first parallel resonator outside the band and introducing an out-of-band zero point outside the band through the low-pass filter circuit.

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;

the labels in the figure are: 1. an LTCC substrate layer; 2. a low-pass filter circuit; 3. a band-pass filter circuit.

Detailed Description

The invention 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 first parallel resonator 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 first parallel resonator, 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, the third series resonator is connected to a second parallel resonator connected to ground, and an out-of-band zero is introduced into the low-pass filter circuit to increase out-of-band rejection of the low-pass branch.

As shown in fig. 2, the invention 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 and a band-pass filter circuit 3 inside the ceramic substrate; the typical dimensions of the invention are 2.0X 1.25X 0.59 mm.

As shown in fig. 3, the LTCC substrate layer 1 includes eleven circuit layers therein, wherein: the inductor (1-L1) and the inductor (1-L2) are printed on the ceramic dielectric, wherein 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 a 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 a 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 a 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 a through hole (3-V3); a fourth layer, wherein a capacitor (4-C2) is printed on the ceramic dielectric, one end of the capacitor (4-C2) is connected with the low-frequency signal output port P2, and a through hole (3-V3) is connected with a through hole (4-V3); a fifth layer, a capacitor (5-C1) and a capacitor (5-C2) are printed on the ceramic dielectric, wherein the capacitor (5-C1) is connected with the through hole (4-V3), and the capacitor (5-C1) is connected with the capacitor (5-C2) through a connecting line; a sixth layer, a capacitor (6-C1) is printed on the ceramic dielectric and is used as an isolated large ground of the low-pass filter circuit and the band-pass filter circuit, and the capacitor (6-C1) is connected with the ports G1, G2 and G3; 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, one end of the inductor 7-L5 is connected with the capacitor 7-C5, the other end of the inductor 7-L5 is connected with a through hole 7-V5, one end of the inductor 7L6 is connected with the capacitor 7-C6, the other end of the inductor 7-L6 is connected with the through hole 7-V6, and the inductor 7-L6 and the capacitor 7-C6 are connected with a ground port G3 through a connecting wire; an eighth layer, wherein an inductor 8-L5, an inductor 8-L6, a capacitor 8-C5 and a capacitor 8-C6 are printed on the ceramic dielectric, wherein the capacitor 8-C5 is connected with a through hole 8-V4, one end of the inductor 8-L5 is connected with a through hole 7-V5, the other end of the inductor 8-L5 is connected with the capacitor 8-C6, the capacitor 8-C6 is connected with the inductor 8-L6, and the other end of the inductor 8-L6 is connected with the through hole 7-V6; a ninth layer, wherein inductors 9-L3 and inductors 9-L4 are printed on the ceramic dielectric, one end of each inductor 9-L3 is connected with 9-V7, the other end of each inductor 9-L3 is connected with a high-frequency output port P3, one end of each inductor 9-L4 is connected with 9-V8, the other end of each inductor 9-L4 is connected with a common input port P1, and through holes 9-V4 are connected with through holes 8-V4; 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 a through hole 10-V7, one end of the inductor 10-L3 is connected with the through hole 9-V8, the other end of the inductor 10-L3 is connected with a through hole 10-V8, the capacitor 10-C3 is connected with one end of the capacitor 10-C4, and the through hole 9-V4 is connected between the capacitor 10-C3 and the capacitor 10-C4; in the eleventh layer, an inductor 11-L3, an inductor 11-L4, a capacitor 11-C3 and a capacitor 11-C4 are printed on a ceramic medium, wherein one end of the inductor 11-L3 is connected with a through hole 10-V7, the other end of the inductor 11-L4 is connected with a capacitor 11-C3, one end of the inductor 11-L4 is connected with the through hole 10-V8, and the other end of the inductor 11-L4 is connected with the capacitor 11-C5.

As shown in FIG. 4, 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 return loss of the duplexer is better than 15dB, the isolation between 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 25dB, 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 invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a duplexer with low frequency transmission zero based on LTCC technology, a serial communication port, including LTCC base member layer, LTCC base member layer is formed with 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 first parallel resonator between sharing input port and low frequency output port, is connected with the first electric capacity of ground connection between first inductance and the first parallel resonator, 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 second parallel resonator of ground connection.

2. The LTCC process based duplexer with low frequency transmission zero according to claim 1, wherein: 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.

3. The LTCC process based duplexer with low frequency transmission zero according to claim 1, wherein: the capacitors of the low-pass filter circuit and the band-pass filter circuit adopt MIM capacitors formed between an upper plate and a lower plate.

4. The LTCC process based duplexer with low frequency transmission zero according to claim 1, wherein: the LTCC substrate is characterized in that the LTCC substrate layer is internally provided with eleven circuit layers, a first inductor of a low-pass filter circuit and an inductor of a first parallel resonator are formed on the first layer, the second layer and the third layer, a first capacitor is formed on the fifth layer and the sixth layer, a capacitor of the first parallel resonator is formed on the fourth layer and the fifth layer, a third series resonator and a first parallel resonator of a band-pass filter circuit are formed on the seventh layer and the eighth layer, and a first series resonator and a second series resonator of the band-pass filter circuit are formed on the ninth layer, the tenth layer and the eleventh layer.

5. The LTCC process based duplexer with low frequency transmission zero according to claim 4, wherein: the first inductor is connected with the common input port through an inductor wire of a third layer, the inductor of the first parallel resonator is connected with the low-frequency output port through an inductor wire of a third layer, the capacitor of the first parallel resonator is connected with the low-frequency output port at a fourth layer, 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 a ninth layer, the second series resonator is connected with the high-frequency output port through an inductor wire of the ninth layer, the first series resonator, the second series resonator, the third series resonator and the first parallel resonator are connected through connecting through holes, and the second parallel resonator is connected with the ground port through a connecting wire of a sixth layer.