CN209627337U - A 5G high-performance LTCC bandpass filter for suppressing high-order harmonics - Google Patents

Abstract

The utility model discloses a kind of LTCC bandpass filter, including matrix, input terminal electrode, output terminal electrode, ground connection termination electrode and internal circuit；The internal circuit includes three parallel resonances, three coupling inductances, two connection capacitors and a source-load coupled capacitor, further includes three pieces of ground connection pole plates, and one of ground connection pole plate uses defect ground structure；Realize these inductance, filter is made on LTCC green surface, and by punching, filling perforation, wire mark, lamination and sintering process in the conductor printing of capacity cell；Internal circuit uses LTCC vertical interconnecting structure, and inductance uses twin stack configuration, and capacitor uses MIM formula capacitor, is connected between inductance and capacitor by vertical through hole.The bandpass filter is small in size, and production cost is low, can be mass, and passband introduces three transmission zeros up to 1GHz and small with interior Insertion Loss, and Out-of-band rejection is high and low-resistance belt sideband is precipitous, and using mirror image, performance reliability is high.

Description

A 5G high-performance LTCC bandpass filter for suppressing high-order harmonics

technical field

The utility model relates to the technical field of filters, in particular to a 5G high-performance LTCC bandpass filter for suppressing high-order harmonics.

Background technique

Microwave bandpass filter is a key component of microwave radio frequency system. With the development of microwave circuit design simulation technology and technology in recent years, the demand for miniaturization of radio frequency system is getting higher and higher, and the miniaturization of filter is the first to bear the brunt , how to reduce the size of the filter as much as possible while ensuring a certain performance index has become an important problem to be solved in the miniaturized radio frequency system. At the same time, with the rapid development of wireless communication systems, frequency resources are increasingly tight. In order to suppress external signals and high-order harmonics generated by components such as mixers and oscillators, and improve the electrical performance of the whole machine, the filter is required to have good out-of-band suppression. ability.

Low-temperature co-fired ceramics is an electronic packaging technology that uses a multilayer ceramic process to place passive components inside a ceramic dielectric. LTCC (Low Temperature Co-fired Ceramics) technology is a multilayer ceramic technology developed in recent years. Using this technology, three-dimensional structures that cannot be realized by traditional ceramic substrate technology can be realized. Designing microwave passive devices using LTCC technology has great flexibility. How to make full use of the advantages of the LTCC process, determine the structure of the filter through a reasonable layout, and make the design have a certain stability, and maintain the success rate of the product within the necessary processing error range is a key issue in the design of the LTCC filter .

However, the frequency response of the traditional filter will produce a spurious passband when it is a certain distance away from the main passband (usually an integer multiple of the center frequency of the main passband), which is not suitable for applications that require harmonic suppression.

Utility model content

Aiming at the deficiencies of the existing technology, this utility model proposes a 5G high-performance LTCC bandpass filter that suppresses high-order harmonics. The filter uses LTCC technology, which greatly reduces the size of the device, only 1.6mm* 0.8mm*0.6mm; the internal circuit adopts a left-right symmetrical structure, and the complexity of the design is reduced through a reasonable layout and the use of coupling between components; at the same time, a coupling capacitor is added between the source and the load, and the low-end stop band Multiple transmission zeros are generated, and three groups of LC series resonances are respectively added to the three resonance units to form transmission zeros in the high-end stop band. While suppressing high-order harmonics in the stop band, the stop band attenuation is increased to obtain a wider stopband range. The specific technical scheme is as follows:

A 5G high-performance LTCC bandpass filter for suppressing high-order harmonics, including a substrate, an input terminal electrode, an output terminal electrode, a ground terminal electrode, and an internal circuit; the substrate includes a multi-layer LTCC ceramic substrate, wherein the The input terminal electrode and the output terminal electrode are respectively arranged at opposite ends of the filter in the length direction, and the ground terminal electrode is arranged outside the middle part in the filter length direction;

The internal circuit includes the first inductance L1 and the first capacitor C1 connected in parallel to form the first resonance, the second inductance L2 and the second capacitor C2 connected in parallel to form the second resonance, and the second inductor L2 and the second capacitor C2 connected in parallel to form the third resonance. The third inductance L3 and the third capacitor C3 are connected by capacitors between the resonances, including the source-load coupling capacitor C, and three ground plates, one of which adopts a defective ground structure to realize the conductor printing of these inductors and capacitors in LTCC production Porcelain surface, and the filter is made by drilling, filling, screen printing, lamination and sintering processes; the filter as a whole adopts the unique vertical interconnection structure of LTCC;

The first, second, and third inductors L1, L2, and L3 are implemented by stacked inductors on multilayer ceramic dielectrics. Metal conductors on different ceramic dielectric layers are connected through through holes. By adjusting the length of each layer of the stacked inductor line, the line wide to adjust the inductance value;

The first, second, third, fourth, fifth, and source-load coupling capacitors C1, C2, C3, C4, C5, and C are realized by planar capacitor plates of multilayer ceramic dielectric layers, between different ceramic dielectric layers The capacitive plates are interconnected through the mutual coupling between the plates and through holes, and the capacitance value is adjusted by adjusting the size of the plates;

The internal circuit part of the bandpass filter has 11 layers in total, the first layer, the eleventh layer and the third layer are the whole ground layer, and the third layer ground layer is a defect ground structure, and the three layers of ground layers are connected to both sides of the substrate. The ground terminal electrode is connected;

The first resonance of the bandpass filter is located on the left side of the internal circuit structure, the first capacitor C1 is located on the fourth layer of the circuit, one end is connected to the lower plate of the fourth capacitor C4 on the sixth layer through a through hole, and the first inductor L1 is located on the circuit The eighth and ninth layers, wherein one end of the inductor L1 is connected to the ground electrode, and the other end is connected to the lower plate of the capacitor C4 through a through hole;

The third resonance is located on the right side of the internal circuit structure. The third capacitor C3 is located on the fourth layer of the circuit. One end is connected to the lower plate of the fifth capacitor C5 on the sixth layer through a through hole. The third inductor L3 is located on the eighth and ninth layers of the circuit. , wherein one end of the inductor L3 is connected to the ground terminal electrode, and the other end is connected to the lower plate of the capacitor C5 through a through hole;

The second resonance is located in the middle of the internal circuit structure, and the second capacitor C2 is located on the second layer of the circuit. It passes through the defective ground structure through a through hole and connects to the dumbbell-shaped plate on the fifth layer. This plate is connected to the lower plate of C4 and the lower plate of C5. Capacitors C4 and C5 are formed, and the second inductance L2 is located on the 8th and 9th layers of the circuit, wherein one end of the inductance L2 is connected to the ground layer of the 11th layer through a through hole, and the other end is connected to C2 through a through hole;

The source-load coupling capacitor is located on the seventh layer of the circuit. It is a dumbbell-shaped structure that generates a transmission zero point in the low-stop band. At the same time, L1 acts as a ground inductance to form a series resonance with C1, forming a transmission zero point in the high-end stop band. Similarly, L2 and C2, L3 and C3 respectively form a series resonance and form a transmission zero at the high end.

Further, one end of the first capacitor C1 is connected to a pole plate on the left side of the 10th layer of the circuit through a through hole, and the other end of the plate is connected to the input port of the left end; one end of the third capacitor C3 is connected to a pole on the right side of the 10th layer of the circuit through a through hole The plate is connected, and the other end of the plate is connected to the output port on the right.

Further, the structure of the inductor L1, the capacitors C1, C4 and the structure of the inductor L3, the capacitors C3, C5 are mirror images.

Furthermore, the lower plates of capacitors C4 and C5 in the sixth layer of the circuit are incomplete rectangular structures, and there is a quarter-circle gap with a radius of 0.22 mm.

Further, the base size of the filter is 0.8mm×1.6mm×0.6mm.

Further, the passband range of the filter is 4.99-5.95GHz, the maximum insertion loss of the passband is 1.2dB, a transmission zero is generated at 2.45GHz and 3.68GHz at the low-end stopband, and a transmission zero is generated at 12.73GHz at the high-end stopband Transmission zero, attenuation greater than 25dB at 15GHz in the high-end stop band.

The beneficial effects of the utility model are as follows:

(1) Using LTCC multi-layer process to make the structure of the filter more compact, this process can effectively reduce the size of components, in line with the trend of miniaturization;

(2) The creative use of a three-layer internal ground structure, the use of the top and bottom ground layers can effectively reduce the impact of external circuits, and the use of the third-layer defective ground structure of the internal circuit can effectively suppress the parasitic coupling effect between components, The performance of the filter is more stable, and at the same time, it provides a ground plane for the ground parallel coupling capacitor, which makes the design of parallel resonance more flexible, greatly optimizes the complexity of the design, and realizes it with fewer components and a simpler structure A third-order bandpass filter is introduced, which reduces the size of the device to a certain extent and reduces the difficulty of debugging;

(3) The application of the source-load coupling capacitor produces a transmission zero point in the low-end stop band. What is more worth mentioning is that the inductors L1, L2, and L3 are used as the resonant inductor of the parallel resonant unit, and they are respectively connected with C1, C2, C3 forms series resonance, which constitutes a double resonance unit structure of LC series resonance and capacitor C to form parallel resonance. The use of this structure greatly simplifies the internal circuit structure and increases space utilization. At the same time, the high-end stop band 12.73 A zero point is generated at GHz, so that the suppression of the second harmonic at 10GHz reaches 25dB, and the suppression of the third harmonic at 15GHz reaches 30dB, which effectively suppresses high-order harmonics and increases the range of the stop band. Combined with the zero point of the low-end stop band, high Stop-band suppression performance.

(4) The filter adopts a 3rd-order symmetrical resonant unit as a whole, and the fewer orders make the maximum insertion loss in the passband only 1.2dB, reaching the low insertion loss index.

(5) In order to overcome the shortcomings of traditional planar spiral inductors in the vertical direction, such as low utilization efficiency and high strays that are difficult to suppress, a double-layer stacked inductor is used in this paper, and the Q value of the inductor is greatly improved under the premise of a small change in the inductance value. Improve the filtering performance of the entire filter.

Description of drawings

Fig. 1 is the outline drawing of the LTCC band-pass filter of the present utility model;

Fig. 2 is the internal circuit diagram of the LTCC band-pass filter of the present utility model;

Fig. 3 is the front structural diagram of the LTCC band-pass filter of the present utility model;

Fig. 4 is the first layer 3D structural diagram of the LTCC band-pass filter of the present utility model;

Fig. 5 is the 2nd layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 6 is the 3rd layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 7 is the 4th layer 3D structural diagram of the LTCC band-pass filter of the present utility model;

Fig. 8 is the 5th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 9 is the 6th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 10 is the 7th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 11 is the 8th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 12 is the 9th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 13 is the 10th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 14 is the 11th layer 3D structural diagram of the LTCC bandpass filter of the present utility model;

Fig. 15 is the S parameter simulation result diagram of the LTCC bandpass filter of the present invention, wherein Fig. 15a is the s21 parameter result diagram, and Fig. 15b is the s11 parameter result diagram.

Detailed ways

The utility model will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effect of the utility model will become clearer. The utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

Figure 1 is the overall outline of a band-pass filter implemented using LTCC technology, including the LTCC ceramic base shell. On the outside of the middle part in the length direction of the substrate, a weldable metal conductor strip is printed as the ground electrode GND of the filter; on the opposite ends of the filter substrate in the length direction, weldable metal conductors are covered as the input electrode IN and output of the filter Electrode OUT.

In this embodiment, the external dimensions of the LTCC bandpass filter are 0.8mm×1.6mm×0.6mm, the relative dielectric constant of the LTCC ceramic medium used is 9.8, the loss tangent is 0.002, and the thickness of each layer of ceramic medium is 0.05mm. The metal conductor material is metallic silver.

Fig. 2 is an internal circuit diagram of the band-pass filter of the present invention, and Fig. 3 is a front structural diagram of the LTCC band-pass filter. It can be seen from the figure that the 3D structure adopts the form of vertical interconnection as a whole, and has a total of 11 layers; the top layer, the bottom layer and the third layer of the circuit are internal grounds, and the third layer is a defect ground structure, which is convenient for ground resonance The design and layout of capacitors C1, C2, and C3 can effectively reduce the coupling and parasitic effects between components; because the required inductance value is small, the inductor adopts a double-layer stacked structure; the capacitor adopts a MIM structure, and the structure's The capacitor has a large Q value and stable performance;

It can be seen from Figure 3 that in the 3D circuit, the first resonance and the third resonance are mirror-image symmetric, that is, the size and relative position of the components are the same; Ground capacitor C1, one end of which is connected to the input end through a through hole and the connecting plate of the tenth layer, and the other end is connected to one end of the inductor L1 of the 8th and 9th layers through a through hole to form a parallel resonance, and the other end of the inductor L1 Grounding; the third resonant structure is the same as the first resonant structure; the second layer of the circuit forms a capacitance C2 to the ground with the first and third layers of the ground, and is connected to one end of the inductor L2 of the eighth and ninth layers through a through hole to form The second parallel resonance, the other end of the inductor L2 is grounded; the left and right plates of the sixth layer of the circuit are the lower plates of the capacitor C4 and capacitor C5 respectively, and the capacitors C4 and C5 are coupled with the fifth layer of the circuit; the capacitor C4 of the sixth layer of the circuit , The lower plate of C5 is an incomplete rectangular structure, and there is a quarter-circle gap with a radius of 0.22mm. At the same time, the resonances of all levels are connected through capacitors; among them, one end of the lower plate of capacitor C4 is connected to the through hole connecting C1 and L1, and one end of the lower plate of capacitor C5 is connected to the through hole connecting C3 and L3; the above structure constitutes a band pass The basic topology of the filter has a filtering effect; in order to increase the attenuation effect of the stop band of the filter, a dumbbell-shaped plate on the seventh layer of the circuit is added, which is coupled with the sixth layer of the plate to form a source-load coupling capacitance. At the same time, L1 is also As a ground inductor, it forms a series resonance with C1, forming a transmission zero point in the high-end stop band. Similarly, L2 and C2, L3 and C3 respectively form a series resonance, forming a transmission zero point at the high end, thereby adding multiple transmission zero points in the stop band to improve stopband characteristics. The specific structure of the filter circuit is shown in Figure 4-Figure 14.

Figure 15 is the S-parameter simulation diagram of the LTCC bandpass filter. As shown in the figure, in the filter passband range of 4.99-5.95GHz, the maximum insertion loss of the filter is less than 1.2dB, and in the low-end stopband of 2.45GHz, 3.68 A transmission zero point is generated at GHz respectively, with a steep low-end stopband characteristic curve, and a transmission zero point is generated at 12.73GHz at the high-end stopband, making the attenuation at 10GHz greater than 25dB, and the attenuation at 30GHz reaches 30dB, suppressing the attenuation of the high-end stopband Higher harmonics make the filter have a wider stopband characteristic.

To sum up, the LTCC bandpass filter provided by the utility model has the characteristics of small size, small insertion loss, high out-of-band suppression, and wide stopband range. It can be patched and welded, and is easy to integrate with other microwave components. Moreover, the utility model is based on LTCC technology, has low manufacturing cost and is suitable for mass production.

Those of ordinary skill in the art can understand that the above description is only a preferred example of the utility model, and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing examples, for those skilled in the art, the It is still possible to modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features. All modifications, equivalent replacements, etc. within the spirit and principles of the utility model shall be included in the protection scope of the utility model.

Claims (6)

1. a kind of 5G high-performance LTCC bandpass filter for inhibiting higher hamonic wave, including matrix, input terminal electrode, output end electricity Pole, ground connection termination electrode and internal circuit；The intrinsic silicon includes multilayer LTCC ceramic substrate, wherein the input terminal Electrode and output terminal electrode are respectively arranged on the opposite end on the filter length direction, and the ground connection termination electrode is set to filtering On the outside of middle part on device length direction；

The internal circuit includes the first inductance L1 and first capacitor C1 for the first resonance of composition being connected in parallel, is connected in parallel The the second inductance L2 and the second capacitor C2 of the second resonance of composition, the third inductance L3 for the composition third resonance being connected in parallel and Three capacitor C3 further include source-load coupled capacitor C, three pieces of ground connection pole plates, one of use by capacitance connection between resonance Defect ground structure, realize the conductor printing of these inductance, capacity cell on LTCC green surface, and pass through punching, filling perforation, net Filter is made in print, lamination and sintering process；Filter integrally uses the distinctive vertical interconnecting structure of LTCC；

First, second, third inductance L1, L2, L3 is using the laminated inductor realization on multiple layer ceramic dielectric, different ceramic dielectric layers On metallic conductor connected by through-hole, by adjusting the wire length of every layer of laminated inductor line, line width adjusts inductance value；

The first, second, third, fourth, the 5th and source-load coupled capacitor C1, C2, C3, C4, C5, C is situated between by multi-layer ceramics The plane capacitance pole plate of matter layer realizes that the capacitor plate between different ceramic dielectric layers is by intercoupling between pole plate and leads to Interconnection is realized in hole, carrys out capacitance value by adjusting the size of pole plate；

Bandpass filter internal circuit part shares 11 layers, and the 1st layer, 11th layer and the 3rd layer are full wafer ground plane, wherein 3rd layer of ground plane is defect ground structure, and three layers of ground plane are connected with the ground connection termination electrode of matrix two sides；

On the left of the internally positioned circuit structure of the first resonance of bandpass filter, first capacitor C1 is located at the 4th layer of circuit, and one end is logical Through-hole is crossed to be connected with junior's pole plate of the 6th layer of the 4th capacitor C4, the first inductance L1 is located at circuit the 8th, and the 9th layer, wherein inductance L1 One end is connected with the ground connection termination electrode, and the other end is connected by through-hole with capacitor C4 bottom crown；

On the right side of the internally positioned circuit structure of third resonance, third capacitor C3 is located at the 4th layer of circuit, and one end passes through through-hole and the 6th layer Junior's pole plate of 5th capacitor C5 is connected, and third inductance L3 is located at circuit the 8th, and the 9th layer, wherein the one end inductance L3 connects with described Ground termination electrode is connected, and the other end is connected by through-hole with capacitor C5 bottom crown；

In the middle part of the internally positioned circuit structure of second resonance, the second capacitor C2 is located at the circuit second layer, across defect by through-hole Structure is connected with the 5th layer of dumbbell shape pole plate, and the pole plate and C4 bottom crown and C5 bottom crown constitute capacitor C4, C5, the second inductance L2 is located at the 8th, the 9th layer of circuit, and wherein the one end inductance L2 is connected by through-hole with 11th layer ground plane, the other end pass through through-hole and C2 is connected；

Source-load coupled capacitor is located at the 7th layer of circuit, is dumbbell shape structure, generates transmission zero in low-resistance belt, meanwhile, L1 is again Series resonance is formed as lower ground inductance and C1, forms transmission zero in high-end stopband, similarly, L2 and C2, L3 and C3 distinguish shape At series resonance, in high-end formation transmission zero.

2. LTCC bandpass filter according to claim 1, which is characterized in that the one end first capacitor C1 passes through through-hole and electricity A pole plate is connected on the left of the 10th floor of road, and the pole plate other end is connected with left end input port；Third one end capacitor C3 by through-hole with The 10th layer of one pole plate of right side of circuit is connected, and the pole plate other end is connected with right end output port.

3. LTCC bandpass filter according to claim 1, which is characterized in that inductance L1, the structure of capacitor C1, C4 and electricity Feel L3, the structure of capacitor C3, C5 are in mirror symmetry.

4. LTCC bandpass filter according to claim 1, which is characterized in that the 6th layer capacitance C4 of circuit, the bottom crown of C5 For incomplete rectangular configuration, there are a quarter circumferential notches that radius is 0.22mm.

5. LTCC bandpass filter according to claim 1, which is characterized in that the matrix of filter having a size of 0.8mm × 1.6mm×0.6mm。

6. LTCC bandpass filter according to claim 1, which is characterized in that the free transmission range of filter is 4.99- 5.95GHz, passband maximum insertion are 1.2dB, generate a transmission zero respectively at low side stopband 2.45GHz, 3.68GHz Point generates a transmission zero at high-end stopband 12.73GHz, and the decaying at high-end stopband 15GHz is greater than 25dB.