CN105552491B - A kind of miniature L frequency ranges lamination broadband band-pass filter - Google Patents

Abstract

The invention relates to a miniature L-band multilayer wideband bandpass filter, which includes a surface-mounted input port and an output port, a first ground port, a second ground port, an input inductance, an output inductance, a first-stage resonant circuit, A three-stage resonant circuit composed of a second-stage resonant circuit and a third-stage resonant circuit, a first grounding plate, a second grounding plate and a U-shaped trap circuit. The input port is connected to the input inductor through a first vertical via. The output port is connected to the output inductor through a second vertical via. The invention has the characteristics of small size, high reliability, simple and compact structure, high yield, excellent frequency characteristics, high out-of-band suppression, high processing consistency, etc., and can realize mass production.

Description

A Miniature L-Band Laminated Broadband Bandpass Filter

technical field

The invention relates to the technical field of filters, in particular to a miniature L-band laminated broadband bandpass filter.

Background technique

Low-temperature co-fired ceramic (LTCC) technology adopts a three-dimensional lamination process, which can embed passive components in ceramic substrates, and can also mount active components on the surface of the substrate to make passive/active integrated functional modules. The three-dimensional structure, layered design, and overall sintering provide a stable, reliable, small-volume, and high-performance electronic packaging form for the device. Compared with LC filters, cavity filters, and dielectric filters, LTCC filters have the characteristics of small size, light weight, stable performance, and high consistency.

In the past, the broadband bandpass filter design of the laminated process often used a lumped parameter resonant circuit and a broadside coupling structure. The resonant plates of the adjacent stages were distributed on the upper and lower layers. The resonant plates of each stage were connected to the ground with vertical through holes, respectively forming Capacitance, inductance, and some are often added to the notch circuit in order to improve the out-of-band suppression. As can be seen from the structure shown in FIG. 4 , this broadband bandpass filter consists of an input conductor 2 , an output conductor 3 , a resonant plate 4 , a through hole 5 and a floor 1 . Adjusting the relative area of the upper and lower plates can change the coupling of adjacent stages, thereby adjusting the bandwidth, but there are few adjustment parameters and poor flexibility. In order to obtain larger capacitance and inductance, it is necessary to increase the area of the resonant plate or the length of the vertical through hole, which greatly increases the volume of the filter, which is not conducive to the miniaturization of the device, and does not give full play to the advantages of the LTCC stacking process.

The signal end of the filter is often led to the top and bottom layers by side printing. Since the LTCC filter is small in size, reaching the millimeter level, and the leading tap end is only a few tenths of a millimeter, the yield rate is low during side printing and the product is reliable. Sex is not high.

Contents of the invention

The purpose of the present invention is to provide a miniature L-band multilayer broadband bandpass filter, which has the advantages of small size, high reliability, simple and compact structure, high yield, excellent frequency characteristics, high out-of-band rejection, It has high processing consistency and can realize mass production.

To achieve the above object, the present invention adopts the following technical solutions:

A miniature L-band multilayer broadband bandpass filter, including surface-mounted input ports and output ports, a first ground port, a second ground port, an input inductance, an output inductance, a first-stage resonant circuit, a second-stage A three-stage resonant circuit composed of the resonant circuit and the third-stage resonant circuit, a first grounding plate, a second grounding plate and a U-shaped trap circuit. The input port is connected to the input inductor through a first vertical via. The output port is connected to the output inductor through a second vertical via.

The first stage resonant circuit includes a first resonant unit, a first loading capacitor circuit and a first series inductance circuit arranged sequentially from top to bottom. The second-stage resonant circuit includes a second resonant unit, a second loading capacitor circuit and a second series inductance circuit arranged sequentially from bottom to top. The third-level resonant circuit includes a third resonant unit, a third loading capacitor circuit and a third series inductance circuit arranged sequentially from top to bottom.

The first resonant unit and the third resonant unit are arranged symmetrically and distributed on the same layer. The second resonant unit is located on a layer above the first resonant unit and the third resonant unit. The first loading capacitor circuit and the third loading capacitor circuit are arranged symmetrically and distributed on the same layer. The U-shaped trap circuit is located on the same layer as the first loading capacitor circuit and the third loading capacitor circuit, and the U-shaped trap circuit is connected in series between the first loading capacitor circuit and the third loading capacitor circuit. between capacitor circuits. Both ends of the U-shaped trap circuit are connected to the second ground port.

The first resonance unit is connected in series with the input inductor. The first resonant unit is connected to the first series inductance circuit through a third vertical via hole. The first series inductance circuit is connected to the second ground plate through a fourth vertical via hole. The third resonance unit is connected in series with the output inductor. The third resonant unit is connected to the third series inductance circuit through a fifth vertical via hole. The third series inductance circuit is connected to the second ground plate through a sixth vertical via hole. The second ground plate is connected to the second ground port. The second resonant unit is connected to the second series inductance circuit through a seventh vertical via hole. The second series inductance circuit is connected to the first ground plate through the eighth vertical via hole. The first ground plate is connected to the first ground port.

Further, the first resonant unit, the second resonant unit and the third resonant unit are all realized by adopting stepped impedance stripline (SIR structure). The first loading capacitor circuit, the second loading capacitor circuit and the third loading capacitor circuit are all realized by plate capacitors. The first series inductance circuit, the second series inductance circuit and the third series inductance circuit are all realized by snake-shaped inductance.

Further, the first vertical via hole, the second vertical via hole, the third vertical via hole, the fourth vertical via hole, the fifth vertical via hole, the sixth vertical via hole, the seventh vertical via hole and the eighth vertical via hole The through holes are all filled with conductive material. The conductive material is any one or a combination of Ag, Pd, Au, Ag/Pd.

Compared with the prior art, the present invention adopts multi-layer low-temperature co-fired ceramic technology and three-dimensional integration technology, and distributes the three-stage resonant circuits in different layers, and each resonant circuit adopts a SIR structure in series with serpentine inductors (that is, each stage The resonant unit of the resonant circuit is connected in series with the inductance circuit), which can not only greatly reduce the volume of the component under the same dielectric constant; it can also adjust the height of the upper and lower resonant circuits or the distance between the resonant units of the SIR structure. Precisely change the degree of coupling between resonant elements. The invention can also be used in the design of the narrowband filter, and can easily realize the adjustment of the resonant frequency by changing the area of the loading capacitor circuit or the length of the serpentine inductance coil. Each stage of the resonant circuit in the present invention adopts a semi-lumped and semi-distributed structure, which can ensure smooth passband and low insertion loss while reducing the size of the resonant circuit. In the present invention, the notch circuit composed of the first-stage resonant circuit, the third-stage resonant circuit and the U-shaped strip line can obtain an attenuation pole near the passband and obtain a bandpass filter with a steep transition band. In the present invention, the signal lead-out end of the filter described in the present invention is connected to the input and output ports through vertical through holes, thereby improving the reliability of the ports. The invention has the characteristics of small size, high reliability, simple and compact structure, high yield, excellent frequency characteristics, high out-of-band suppression, high processing consistency, etc., and can realize mass production.

Description of drawings

Fig. 1 is the structural representation of L frequency band lamination broadband bandpass filter of the present invention;

Fig. 2 is the cross-sectional schematic view of the L-band laminated broadband bandpass filter of the present invention;

Fig. 3 is the scattering parameter (being S parameter, S11 is the input reflection coefficient, S21 is the forward transmission coefficient) characteristic curve of the L-band laminated broadband bandpass filter of the present invention;

Fig. 4 is a schematic diagram of the structure of a conventional laminated broadband bandpass filter.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

An L-band multilayer broadband bandpass filter as shown in Figures 1-2, including a surface-mounted 50-ohm impedance input port a1, a surface-mounted 50-ohm impedance output port a2, a first ground port b1, The second ground port b2, the input inductance c1, the output inductance c2, the three-stage resonant circuit (s1, s2, s3), the first ground plate e1, the second ground plate e2 and the U-shaped trap circuit u. Wherein, the 50 ohm impedance input port a1 is connected to the input inductor c through the first vertical through hole d1. The 50 ohm impedance output port a2 is connected to the output inductor c2 through the second vertical through hole d2. Both the first vertical through hole and the second vertical through hole are filled with conductive material, and the conductive material is any one or a combination of Ag, Pd, Au, Ag/Pd.

The three-stage resonant circuit includes a first-stage resonant circuit s1, a second-stage resonant circuit s2, and a third-stage resonant circuit s3. The first stage resonant circuit s1 is composed of a first resonant unit s11, a first loading capacitor circuit s12 and a first series inductance circuit s13. The second level resonant circuit s2 is composed of a second level resonant unit s21, a second loading capacitor circuit s22 and a second series inductance circuit s23. The third-level resonant circuit s3 is composed of a third-level resonant unit s31 , a third loading capacitor circuit s32 and a third series inductance circuit s33 . Each level of resonant circuit adopts a semi-lumped and semi-distributed structure. There are three pattern layers. From top to bottom, the order is as follows: the first layer of resonant unit is realized by ladder impedance strip line, and the second layer of loading capacitor circuit is realized by flat plate capacitor. , The third layer of series inductance circuit is realized by snake-shaped inductance. The first-stage resonant circuit s1 and the third-stage resonant circuit s3 are symmetrically arranged and distributed on the same layer, and the second-stage resonant circuit s2 is arranged in the opposite direction and distributed on the adjacent layer with s1 and s3. The pattern layer adopts a printing method, and the material of the pattern layer is any one or a combination of conductive materials Ag, Pd, Au, Ag/Pd. Stack each layer and sinter the whole to obtain a laminated body. The surface-mounted 50-ohm impedance input port a1, output port a2, first ground port b1, and second ground port b2 are all formed by printing and post-firing processes. , and these ports are composed of Ag/Pd, Au, Ni and other materials.

The first resonant unit s11 and the third resonant unit s31 are symmetrically arranged and distributed on the same layer; the second resonant unit s21 is located on the upper layer of the first resonant unit s11 and the third resonant unit s31 . The first loading capacitor circuit s12 and the third loading capacitor circuit s32 are arranged symmetrically and distributed on the same layer. The U-shaped trap circuit u is located on the same layer as the first loading capacitor circuit s12 and the third loading capacitor circuit s32, and the U-shaped trap circuit u is connected in series between the first loading capacitor circuit s12 and the third loading capacitor circuit s32. Between the third loading capacitor circuit s32. Both ends of the U-shaped trap circuit u are connected to the second ground port b2.

The first resonant unit s11 is connected in series with the input inductor c1. The first resonant unit s11 is connected to the first series inductance circuit s13 through a third vertical via d3. The first series inductance circuit s13 is connected to the second ground plate e2 through the fourth vertical through hole d4. The third resonance unit s31 is connected in series with the output inductor c2. The third resonance unit s31 is connected to the third series inductance circuit s33 through a fifth vertical via d5. The third series inductance circuit s33 is connected to the second ground plate e2 through the sixth vertical through hole d6. The second ground plate e2 is connected to the second ground port b2. The second resonance unit s21 is connected to the second series inductance circuit s23 through the seventh vertical via hole d7. The second series inductance circuit s23 is connected to the first ground plate e1 through the eighth vertical through hole d8. The first ground plate e1 is connected to the first ground port b1.

The first resonant unit s11 , the second resonant unit s21 and the third resonant unit s31 are all implemented by using stepped impedance striplines. The first loading capacitor circuit s12 , the second loading capacitor circuit s22 and the third loading capacitor circuit s32 are all realized by plate capacitors. The first series inductance circuit s13 , the second series inductance circuit s23 , and the third series inductance circuit s33 are all realized by snake-shaped inductance.

The first vertical through hole d1, the second vertical through hole d2, the third vertical through hole d3, the fourth vertical through hole d4, the fifth vertical through hole d5, the sixth vertical through hole d6, and the seventh vertical through hole d7 Both the conductive material and the eighth vertical through hole d8 are filled with conductive material; the conductive material is any one or a combination of Ag, Pd, Au, Ag/Pd.

The L-band laminated broadband bandpass filter of the present invention is realized by multi-layer low-temperature co-fired ceramic technology, and its low-temperature co-fired ceramic material and metal wire are sintered at a temperature of about 850°C, which has very high reliability and temperature stability. Moreover, because the structure of the L-band laminated broadband bandpass filter described in the present invention adopts three-dimensional integration and multi-layer folding structure, the volume of the filter can be greatly reduced. The L-band multilayer broadband bandpass filter of the present invention adopts ceramic materials with a dielectric constant of 7.8 and a dielectric loss tangent of 0.002, and the preferred implementation volume is 5.3mm×2mm×1.3mm. The performance of the L-band laminated broadband bandpass filter of the present invention can be seen from simulation curve Fig. 3, and this filter passband is from 1.6Ghz to 2.2Ghz, and the insertion loss in the passband is all less than 1 dB, and the out-of-band suppression Better than -25 dB at 0.8Ghz and 3Ghz, better than -40 dB at 3.1Ghz.

The above-mentioned embodiments are only descriptions of preferred implementations of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (2)

1. A kind of 1. miniature L frequency ranges lamination broadband band-pass filter, it is characterised in that：Including surface-pasted input port（a1）With Output port（a2）, the first ground port（b1）, the second ground port（b2）, input inductance（c1）, outputting inductance（c2）, by the first order Resonance circuit（s1）, second level resonance circuit（s2）With third level resonance circuit（s3）The three-level resonance circuit of composition, first connect Floor（e1）, the second earth plate（e2）With U-shaped trap circuit（u）；The input port（a1）Pass through the first vertical through hole （d1）With the input inductance（c1）It is connected；The output port（a2）Pass through the second vertical through hole（d2）With the outputting inductance （c2）It is connected；

   The first order resonance circuit（s1）Including the first resonant element set gradually from up to down（s11）, first loading electricity Capacitive circuit（s12）With the first series inductance circuit（s13）；The second level resonance circuit（s2）Set gradually including bottom-up The second resonant element（s21）, the second loading capacitance circuit（s22）With the second series inductance circuit（s23）；The third level is humorous Shake circuit（s3）Including the 3rd resonant element set gradually from up to down（s31）, the 3rd loading capacitance circuit（s32）With the 3rd Series inductance circuit（s33）；

   First resonant element（s11）With the 3rd resonant element（s31）It is symmetrical arranged and is distributed in same layer；Described Two resonant elements（s21）Positioned at first resonant element（s11）And the 3rd resonant element（s31）Last layer；It is described First loading capacitance circuit（s12）With the 3rd loading capacitance circuit（s32）It is symmetrical arranged and is distributed in same layer；The U Font trap circuit（u）With the first loading capacitance circuit（s12）And the 3rd loading capacitance circuit（s32）Positioned at same Layer, and the U-shaped trap circuit（u）It is connected on the first loading capacitance circuit（s12）With the 3rd loading capacitance electricity Road（s32）Between；The U-shaped trap circuit（u）Both ends and the second ground port（b2）It is connected；

   First resonant element（s11）With the input inductance（c1）It is connected in series；First resonant element（s11）Pass through 3rd vertical through hole（d3）With the first series inductance circuit（s13）It is connected；The first series inductance circuit（s13）Pass through 4th vertical through hole（d4）With second earth plate（e2）It is connected；3rd resonant element（s31）With the outputting inductance （c2）It is connected in series；3rd resonant element（s31）Pass through the 5th vertical through hole（d5）With the 3rd series inductance circuit （s33）It is connected；The 3rd series inductance circuit（s33）Pass through sextuple clear opening（d6）With second earth plate（e2）Phase Even；Second earth plate（e2）With second ground port（b2）It is connected；Second resonant element（s21）Hung down by the 7th Clear opening（d7）With the second series inductance circuit（s23）It is connected；The second series inductance circuit（s23）Hung down by the 8th Clear opening（d8）With first earth plate（e1）It is connected；First earth plate（e1）With first ground port（b1）Phase Even；

   First resonant element（s11）, the second resonant element（s21）With the 3rd resonant element（s31）Use stepped impedance Strip line is realized；

   The first loading capacitance circuit（s12）, the second loading capacitance circuit（s22）With the 3rd loading capacitance circuit（s32） Realized using capacity plate antenna；

   The first series inductance circuit（s13）, the second series inductance circuit（s23）, the 3rd series inductance circuit（s33）Adopt Realized with snakelike inductance.
2. A kind of 2. miniature L frequency ranges lamination broadband band-pass filter according to claim 1, it is characterised in that：Described first Vertical through hole（d1）, the second vertical through hole（d2）, the 3rd vertical through hole（d3）, the 4th vertical through hole（d4）, the 5th vertical through hole （d5）, sextuple clear opening（d6）, the 7th vertical through hole（d7）With the 8th vertical through hole（d8）Inside it is filled with conductive material； The conductive material is the combination of any one or more in Ag, Pd, Au, Ag/Pd.