Low-insertion-loss multi-transmission-zero-point LTCC band-pass filter applied to 5G communication

Abstract

The invention provides a low-insertion-loss multi-transmission-zero-point LTCC band-pass filter applied to 5G communication, and the filter body comprises a ceramic substrate, an input electrode INPUT, an output electrode OUTPUT and a grounding electrode GND which are disposed at the bottom of the ceramic substrate, and a metal layer disposed in the ceramic substrate. Wherein the metal layer is sequentially provided with a first metal layer, a second metal layer, a third metal layer, a fourth metal layer, a fifth metal layer, a sixth metal layer, a seventh metal layer and an eighth metal layer from bottom to top. According to the filter, cross coupling is introduced into an equivalent resonance circuit to realize four transmission zeros out of band, the requirement of out-of-band high suppression can be met, the filter has the advantages of reliability, high speed, high performance and low cost, integration of passive elements and miniaturization of an electronic system are realized, a multi-layer parallel inductor structure is adopted, and the filter has a wide application prospect. The Q value of the inductor is effectively increased, and the requirements of low insertion loss and multiple transmission zeros of the filter are met.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency filters, and in particular to a low insertion loss and multi-transmission zero LTCC bandpass filter for 5G communications. Background Art

[0002] As a new type of electronic component integration and packaging technology, low-temperature co-fired ceramic technology combines the advantages of thick film technology and HTCC technology, and has excellent mechanical, electrical and thermal properties. It can embed multiple passive components (such as capacitors, resistors, inductors, impedance converters, etc.) into a multi-layer ceramic substrate, stack them together and sinter them at a temperature below 950°C to form a high-density circuit that does not interfere with each other in three-dimensional space, greatly reducing the size of the device. This technology meets the requirements of miniaturization, high stability, and high performance of 5G communications, and can be applied to 5G base station communications, terminal equipment, and enterprise-level networks.

[0003] With the rapid development of modern mobile communications, ultra-wideband and high-frequency technologies have been more widely used in wireless communications. The filters used in 5G communications in the prior art are relatively large in size and have high insertion loss, which makes it difficult to meet the requirements of low insertion loss and multiple transmission zeros for filters. Therefore, the present invention provides a LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communications. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication to solve the problems raised in the above background technology. The present invention adopts a multi-layer parallel inductor structure to effectively increase the Q value of the inductor, reduce the insertion loss of the filter, and achieve the requirements of low insertion loss and multiple transmission zeros of the filter.

[0005] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical scheme: a low insertion loss and multi-transmission zero LTCC bandpass filter applied to 5G communication, the filter body comprising a ceramic substrate, an input electrode INPUT, an output electrode OUTPUT and a ground electrode GND at the bottom of the ceramic substrate, and a metal layer arranged inside the ceramic substrate, wherein the metal layers are arranged in sequence from bottom to top: a first metal layer, a second metal layer, a third metal layer, a fourth metal layer, a fifth metal layer, a sixth metal layer, a seventh metal layer, and an eighth metal layer.

[0006] Furthermore, the first metal layer includes: a concave metal electrode plate located above the grounding electrode, two square metal electrodes on the upper and lower sides of the concave metal electrode plate, connected to the grounding electrode through a through hole; two square metal electrodes on the upper left and right sides of the concave metal electrode plate, which are in a vertical line with the left and right edges of the input and output electrodes, connected to the input and output electrodes respectively downward through the through holes, and connected to the three-layer parallel inductor part above through the through holes.

[0007] Furthermore, the second metal layer includes: located above the two square metal plates in the middle of the first metal layer, and the same as the square metal plates of the first layer, connected to the square metal plates of the first layer and the grounding electrode through through holes; located above the square plates on the left and right sides of the first metal plate, extending to the left and right sides of the concave metal plate to form two convex metal plates, and connected to the input and output electrodes below through through holes and the square metal plates on the left and right sides of the first metal layer, and connected upward to the three layers of parallel inductance above.

[0008] Furthermore, the third metal layer includes: the same square metal plates located above the square metal plates on the left and right sides of the first metal layer, which are connected to the input and output electrodes at the bottom through through holes and connected to the three-layer parallel inductor part at the top; a dish-shaped metal plate located above the grounding electrode, the left and right edges and the middle part of the I-shaped metal plate at the lower part of the dish-shaped metal plate are connected to the three-layer parallel inductor part above through through holes, and there are two upper and lower through holes on the middle line of the dish-shaped metal plate connected to the part of the grounding electrode below.

[0009] Furthermore, the fourth metal layer includes: identical square metal plates located above the square metal plates on the left and right sides of the first metal layer, connected downwardly to the input and output electrodes and upwardly connected to the three-layer parallel inductance part above; a square metal plate located below the dish-shaped metal plate of the third layer and connected to the three-layer parallel inductance part above at four through-hole positions; two knife-shaped metal plates located above the metal plates in the middle part of the second layer, the upper right corner of the left metal plate and the upper left corner of the right metal plate being connected to the three-layer parallel inductance part above through through-holes.

[0010] Furthermore, the fifth metal layer includes: an identical square metal plate located above the four square metal plates in the lower part of the fifth metal layer, which is connected to the three layers of parallel inductance parts above through a through hole; a square plate located above the upper right corner and the upper left corner of the middle part of the fourth metal layer, which is connected to the three layers of parallel inductance parts above through a through hole; and a metal plate with an L-shaped main body formed above the square metal plates located on the left and right sides of the first metal layer, starting from the square metal plate and extending to the middle part of the fourth metal layer, the square plate part is connected downward to the input and output electrodes through a through hole, and is connected upward to the three layers of parallel inductance parts.

[0011] Furthermore, the sixth metal layer includes: two long metal plates located above the edges of both sides of the input and output electrodes, the upper side of the long metal plates is connected downwardly to the input and output electrodes through through holes, and is connected upwardly to the three-layer parallel inductor part, and the lower side of the long metal plates is connected to the upper three-layer parallel inductor part through through holes; an unclosed metal plate shaped like a tripod located in the middle part, the two legs of the lower side of the tripod are connected to the metal plate connected thereto below through through holes, and the unclosed mouth of the upper side of the tripod is connected to the metal plate connected thereto below through through holes.

[0012] Furthermore, the seventh metal layer includes: completely corresponding to the sixth metal layer and connected through a through hole; the eighth metal layer includes: completely corresponding to the sixth and seventh metal layers and connected through a through hole.

[0013] Furthermore, the input electrodes and the output electrodes in the metal layer are symmetrically arranged, and each layer of square metal plates is symmetrically arranged, and the size of the entire miniaturized LTCC bandpass filter is 1.6 mm×0.8 mm×0.6 mm.

[0014] Furthermore, the first layer of concave-shaped metal plates is centrally symmetrically arranged, the second layer of convex-shaped metal plates is bilaterally symmetrically arranged, the third layer of dish-shaped metal plates is centrally symmetrically arranged, the fourth layer of knife-shaped metal plates is bilaterally symmetrically arranged, the fifth layer of L-shaped metal plates is bilaterally symmetrically arranged, and the sixth layer, the seventh layer and the eighth layer of metal plates are centrally symmetrically arranged.

[0015] Beneficial effects of the present invention:

[0016] 1. The overall size of the low insertion loss and multi-transmission zero LTCC bandpass filter used in 5G communication is 1.6mm×0.8mm×0.6mm, which can achieve the purpose of miniaturization. The filter can achieve four transmission zeros out of the band by introducing cross-coupling in the equivalent resonant circuit, which can meet the requirements of high suppression out of the band. It has the advantages of reliability, high speed, high performance and low cost, and realizes the integration of passive components and the miniaturization of electronic systems.

[0017] 2. The low insertion loss and multiple transmission zero-point LTCC bandpass filter used in 5G communication adopts a multi-layer parallel inductor structure, which effectively increases the Q value of the inductor, reduces the insertion loss of the filter, and realizes the requirements of low insertion loss and multiple transmission zero-points of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a front view of the internal structure of a low insertion loss and multi-transmission zero LTCC bandpass filter for 5G communication according to the present invention;

[0019] Figure 2 This is a rear view of the internal structure of a low insertion loss and multi-transmission zero LTCC bandpass filter for 5G communication according to the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of multi-layer parallel inductors of the filter of the present invention;

[0021] Figure 4 is an equivalent circuit diagram of the filter of the present invention;

[0022] Figure 5 is the filter parameter S of the present invention 11 The simulation result diagram of

[0023] Figure 6 is the filter parameter S of the present invention. 21 The simulation result diagram of

[0024] Figure 7 This is a diagram of the actual test results of the present invention. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0026] See also Figures 1 to 7 , the present invention provides the following technical solution: a low insertion loss multi-transmission zero LTCC bandpass filter for 5G communication, such as Figure 1 and Figure 2 As shown, the present invention provides a LTCC bandpass filter with multiple transmission zeros. The size of the entire LTCC bandpass filter is 1.6mm×0.8mm×0.6mm, and it includes: a ceramic substrate, an input electrode INPUT arranged at the bottom of the ceramic substrate, an output electrode OUTPUT arranged at the bottom of the ceramic substrate, a ground electrode GND arranged at the bottom of the ceramic substrate, and a metal layer arranged inside the ceramic substrate; the input electrode INPUT and the output electrode OUTPUT are symmetrically arranged.

[0027] The metal layers are arranged from bottom to top:

[0028] The first metal layer includes: a concave metal plate 13 located above the ground electrode; four square metal plates 12, 14, 11, and 15 located above, below, left, and right of the concave metal plate. The square metal plates 12 and 14 are connected to the ground electrode through through holes 1 and 2; the square metal plates 11 and 15 are connected to the input and output electrodes downward through through holes 3 and 4, and are connected to the three layers of parallel inductance above.

[0029] The second metal layer includes: the same square metal plates 22 and 23 located above the square metal plates 12 and 14; metal plates 21 and 24 extending inward from the square metal plates at the same position above the square metal plates 11 and 15. The square metal plates 22 and 23 are connected to the ground electrode through through holes 1 and 2; the metal plates 21 and 24 are connected to the input and output electrodes downwardly with the square metal plates 11 and 15 of the first metal layer through through holes 3 and 4, and are connected upwardly with the three layers of parallel inductance parts above.

[0030] The third metal layer includes: square metal plates 31 and 33 located at the same position above the first square metal plates 11 and 15; and a plate-shaped metal plate 32 located in the middle of the square metal plates 31 and 33. The square metal plates 31 and 33 are connected to the input and output electrodes downwardly with the second metal plates 21 and 24 and the first square metal plates 11 and 15 through vias 3 and 4, and are connected to the three layers of parallel inductance above upward; the middle position of the plate-shaped metal plate 32 is connected to the ground electrode with the second square metal plates 22 and 23 and the first square metal plates 12 and 14 through vias 1 and 2.

[0031] The fourth metal layer includes: square metal plates 41 and 47 located at the same position above the third square metal plate; four square metal plates 42, 44, 45, 48 located below; and two metal plates 43 and 46 located in the middle. The square metal plates 41 and 47 are connected downward to the input and output electrodes through vias 3 and 4, and upward to the three-layer parallel inductor part; the square metal plates 42, 44, 45, 48 are connected to the upper three-layer parallel inductor part through vias 5, 6, 7, and 8; the upper right corner and upper left corner of the middle metal plates 43 and 46 are connected to the upper three-layer parallel inductor part through vias 9 and 10.

[0032] The fifth metal layer includes: square metal plates 51, 54, 57 and 58 located above the square metal plates 42, 44, 45 and 48 of the fourth layer; square metal plates 53 and 55 located above the upper right corner and upper left corner of the metal plates 43 and 46 of the fourth layer; and metal plates 52 and 56 extending inward from the square metal plates located above the same position of the square metal plates 41 and 47 of the fourth layer. The metal plates 52 and 56 are connected to the upper three layers of parallel inductance parts with the square metal plates 41 and 47 of the fourth layer through through holes 3 and 4, and are connected downward to the input and output electrodes; the square metal plates 51, 54, 57 and 58 are connected to the upper three layers of parallel inductance parts with the square metal plates 42, 44, 45 and 48 of the fourth layer below the middle metal plate of the third layer through through holes 5, 6, 7 and 8; the square metal plates 53 and 55 are connected to the upper three layers of parallel inductance parts with the metal plates 43 and 46 of the fourth layer through through holes 9 and 10.

[0033] The sixth metal layer includes: metal microstrip lines 61 and 63 located on both sides; and a tripod-shaped metal plate 62 located in the middle. The upper sides of the microstrip lines 61 and 63 are connected to the upper three layers of parallel inductance parts through through-holes 3 and 4 with the metal plates at the corresponding positions of the third, fourth and fifth layers, and are connected downwardly to the input and output electrodes with the metal plates at the corresponding positions; the lower sides of the microstrip lines 61 and 63 and the lower sides of the two legs of the middle metal plate are connected to the upper three layers of parallel inductance parts through through-holes 5, 6, 7 and 8 with the metal plates at the corresponding positions of the third, fourth and fifth layers; the upper side of the middle metal plate 62 is connected to the upper three layers of parallel inductance parts through through-holes 9 and 10.

[0034] The seventh metal layer comprises: the same layout as the sixth metal layer, and vias 3, 4, 5, 6, 7, 8, 9 and 10 are connected to the seventh metal layer.

[0035] The eighth metal layer comprises: the same layout as the sixth and seventh metal layers, and through-holes 3, 4, 5, 6, 7, 8, 9 and 10 are connected to the eighth metal layer.

[0036] The equivalent circuit diagram of the multi-transmission zero LTCC bandpass filter of the present invention is as follows: Figure 4 As shown, where:

[0037] The series connection of the inductor L4 in parallel with the capacitor C4 and the inductor L5 is mainly composed of microstrip lines 61, 71, 81 and through holes 3 and 5;

[0038] The series connection of inductor L10 and parallel capacitors C7 and L11 is mainly composed of microstrip lines 63, 73, 83 and through holes 4 and 8;

[0039] The inductor L1 in parallel with the inductor L7 and the inductor L3 in parallel with the inductor L8 are mainly composed of the plates 62, 72, 82 and the through holes 9, 10, 6 and 7;

[0040] The inductor L2 is mainly composed of the plate 13;

[0041] Capacitor C1 is mainly composed of plate 32;

[0042] Capacitors C2 and C3 are mainly composed of plates 32 and 43, 46;

[0043] The series connection of capacitor C5 and inductor L6, and the series connection of capacitor C6 and inductor L9 are mainly composed of plates 21, 24 and plates 52, 56;

[0044] C4 and L5, C5 and L6, C6 and L9, C7 and L11 form four oscillators;

[0045] Capacitor C1 is introduced to form a transmission zero at the low end and the high end of the filter.

[0046] Inductors L4 and L10 are introduced to form a transmission zero at the low end and high end of the filter.

[0047] The low insertion loss and multiple transmission zero LTCC bandpass filter of the present invention realizes high integration through low temperature co-fired ceramic three-dimensional integration technology, and the overall size is 1.6mm×0.8mm×0.6mm, which can achieve the purpose of low insertion loss and multiple transmission zero points; the filter adopts a 4th order design, and introduces C1, L4 and L10 to form 4 transmission zero points in the out-of-band suppression part, thereby achieving the requirement of high out-of-band suppression.

[0048] See also Figure 3 As shown in Table 1, the present invention adopts a multi-layer parallel inductor structure, which avoids the problems of large space occupation, difficult debugging, and complex manufacturing process in the traditional LTCC filter. The structure can effectively improve the inductor Q value without almost affecting the inductance value, thereby improving the high selectivity of the filter and reducing the loss.

[0049] Table 1 Comparison of effective inductance, SRF and Q value between three-layer parallel inductor and single-layer inductor structure

[0050] Shunt Inductor Model Structure Effective inductance SRF Q Value Single-layer inductor structure Larger Smaller Smaller Three-layer inductor structure Smaller Larger Larger

[0051] See also Figure 5 and Figure 6The simulation results of S parameters S11 and S21 show that the passband range of the filter is 4.5-6.5GHz, the insertion loss in the passband is less than 1.0dB, the out-of-band suppression in the low-frequency stopband 800-3800MHz is greater than 20dB, and the out-of-band suppression in the high-frequency stopband 10000-15000MHz is greater than 30dB.

[0052] See also Figure 7 The actual test results show that the filter design can effectively reduce the insertion loss, and the insertion loss at the center frequency of 5.5GHz can reach -0.58dB.

[0053] In summary, the present invention adopts a plate-through-plate structure to achieve long-distance isolation of the capacitor part and the inductor part, suppress mutual interference, and is conducive to the miniaturization of the device; by introducing a capacitive coupling between two series resonators, and introducing multiple transmission zeros to increase the out-of-band suppression, the out-of-band suppression in the low-frequency end stop band 800-3800MHz is greater than 20dB, and the out-of-band suppression in the high-frequency end stop band 10000-15000MHz is greater than 30dB.

[0054] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

[0055] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A low insertion loss and multi-transmission zero LTCC bandpass filter for 5G communication, characterized in that: The filter body includes a ceramic substrate, an input electrode INPUT, an output electrode OUTPUT and a ground electrode GND at the bottom of the ceramic substrate, and a metal layer arranged inside the ceramic substrate, wherein the metal layers are arranged in sequence from bottom to top: a first metal layer, a second metal layer, a third metal layer, a fourth metal layer, a fifth metal layer, a sixth metal layer, a seventh metal layer, and an eighth metal layer.

2. According to claim 1, a low insertion loss multi-transmission zero LTCC bandpass filter for 5G communication, characterized in that: The first metal layer includes: a concave metal plate located above the grounding electrode, with two square metal plates on the upper and lower sides of the concave metal plate, connected to the grounding electrode through a through hole; two square metal plates on the upper left and right sides of the concave metal plate, which are in a vertical line with the left and right edges of the input and output electrodes, connected to the input and output electrodes respectively downward through the through holes, and connected to the three-layer parallel inductor part above through the through holes.

3. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 2, characterized in that: The second metal layer includes: located above the two square metal plates in the middle of the first metal layer, and the same as the square metal plates of the first layer, connected to the square metal plates of the first layer and the grounding electrode through through holes; located above the square plates on the left and right sides of the first metal plate, extending to the left and right sides of the concave metal plate to form two convex metal plates, and connected to the input and output electrodes below through through holes and the square metal plates on the left and right sides of the first metal layer, and connected upward to the three layers of parallel inductance parts above.

4. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 3, characterized in that: The third metal layer includes: the same square metal plates located above the square metal plates on the left and right sides of the first metal layer, which are connected to the input and output electrodes at the bottom through through holes and connected to the three-layer parallel inductor part at the top; a dish-shaped metal plate located above the grounding electrode, the left and right edges and the middle part of the I-shaped metal plate at the lower part of the dish-shaped metal plate are connected to the three-layer parallel inductor part above through through holes, and there are two upper and lower through holes on the dish-shaped midline connected to the part of the grounding electrode below.

5. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 4, characterized in that: The fourth metal layer includes: identical square metal plates located above the square metal plates on the left and right sides of the first metal layer, connected downwardly to the input and output electrodes and upwardly to the three-layer parallel inductor part above; a square metal plate located below the dish-shaped metal plate of the third layer and connected to the three-layer parallel inductor part above in a straight line with four through-hole positions; two knife-shaped metal plates located above the metal plates in the middle part of the second layer, with the upper right corner of the left metal plate and the upper left corner of the right metal plate connected to the three-layer parallel inductor part above through through-holes.

6. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 5, characterized in that: The fifth metal layer includes: an identical square metal plate located above the four square metal plates in the lower part of the fifth metal layer, which is connected to the three layers of parallel inductance parts above through a through hole; a square plate located above the upper right corner and the upper left corner of the middle part of the fourth metal layer, which is connected to the three layers of parallel inductance parts above through a through hole; and a metal plate with an L-shaped main body formed by starting from the square metal plate and extending to the middle part of the fourth metal layer above the square metal plates on the left and right sides of the first metal layer, and the square plate part is connected downward to the input and output electrodes through a through hole, and is connected upward to the three layers of parallel inductance parts.

7. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 6, characterized in that: The sixth metal layer includes: two long strip metal plates located above the edges of both sides of the input and output electrodes, the upper side of the long strip metal plates is connected downwardly to the input and output electrodes through through holes, and is connected upwardly to the three-layer parallel inductor part, and the lower side of the long strip metal plates is connected to the upper three-layer parallel inductor part through through holes; an unclosed metal plate shaped like a tripod located in the middle part, the two legs of the lower side of the tripod are connected to the metal plate connected thereto through through holes, and the unclosed mouth of the upper side of the tripod is connected to the metal plate connected thereto through through holes.

8. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 7, characterized in that: The seventh metal layer includes: completely corresponding to the sixth metal layer and connected through through holes; the eighth metal layer includes: completely corresponding to the sixth and seventh metal layers and connected through through holes.

9. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 3, characterized in that: The input electrodes and the output electrodes in the metal layer are symmetrically arranged, and the square metal plates in each layer are symmetrically arranged. The size of the entire miniaturized LTCC bandpass filter is 1.6 mm×0.8 mm×0.6 mm.

10. The LTCC bandpass filter with low insertion loss and multiple transmission zeros for 5G communication according to claim 1, characterized in that: The first layer of concave-shaped metal plates is centrally symmetrically arranged, the second layer of convex-shaped metal plates is bilaterally symmetrically arranged, the third layer of dish-shaped metal plates is centrally symmetrically arranged, the fourth layer of knife-shaped metal plates is bilaterally symmetrically arranged, the fifth layer of L-shaped metal plates is bilaterally symmetrically arranged, and the sixth layer, the seventh layer and the eighth layer of metal plates are centrally symmetrically arranged.

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