A kind of miniature multipath bank of filters based on LTCC and DGS
Technical field
The invention belongs to bank of filters technical field, be specifically related to a kind of miniature multipath bank of filters based on LTCC and DGS.
Background technology
In recent years, along with the developing rapidly of microminiaturization of mobile communication, satellite communication and Defensive Avionics System, high-performance, low cost and miniaturization have become the developing direction of microwave current/RF application, all have higher requirement to the performance of microwave filter, size, reliability and cost.In some national defence tip device, present use frequency range is quite full, so the tip device such as satellite communication develop towards millimeter wave band, so microwave and millimeter wave band filter has become the critical electronic parts in this band reception and transmitting branch, the leading indicator describing this component capabilities has had: passband operating frequency range, stop band frequency range, pass band insertion loss, stopband attenuation, passband input/output voltage standing-wave ratio, insertion phase shift and delay/frequency characteristic, temperature stability, volume, weight, reliability etc.But having in particular cases, screening signal being carried out to different frequency proposes new requirement, so bank of filters provides stable outstanding application in this situation system.
LTCC (LTCC) is a kind of Electronic Encapsulating Technology, adopts multi-layer ceramics technology, passive component can be built in medium substrate inside, and also active element can be mounted on substrate surface makes passive/active integrated functional module simultaneously.LTCC technology all shows many merits in cost, integration packaging, wiring live width and distance between centers of tracks, low impedance metal, design diversity and flexibility and high frequency performance etc., has become the mainstream technology of passive integration.The advantages such as it has high q-factor, is convenient to embedded passive device, and thermal diffusivity is good, and reliability is high, high temperature resistant, punching shake, utilize LTCC technology, can well process size little, precision is high, and tight type is good, the microwave device that loss is little.Because LTCC technology has the integrated advantage of 3 D stereo, be widely used for manufacturing various microwave passive components at microwave frequency band, the height realizing passive component is integrated.Based on the stack technology of LTCC technique, can realize three-dimensional integrated, thus various micro microwave filter is had, and size is little, lightweight, performance is excellent, reliability is high, batch production performance consistency is good and the plurality of advantages such as low cost.
If only use a path filter, the screening of a frequency range can only be carried out to a road signal, if but adopt bank of filters, at comprehensive high performance switch chip, while just can realizing selection under different frequency range and switching freely, realize high-performance efficient filtering.In addition the filter of identical performance parameter is realized; adopting that LTCC technique is volume required usually can to realize technique (as microstrip line or strip lines configuration) much bigger than traditional; thus the advantage on engineer applied just highlights; LTCC technique is adopted to realize; in volume little as far as possible, optimized performance can be realized.
Summary of the invention
The object of the present invention is to provide a kind of miniature multipath bank of filters based on LTCC and DGS, screen freely under Neng Dui mono-road signal carries out three road different frequency ranges, and overall dimension is little, insertion loss is little, standing wave performance is good, Out-of-band rejection is high, lightweight, reliability is high, easy to use, applied widely, rate of finished products is high, batch consistency is good, cost is low.
In order to solve the problems of the technologies described above, the present invention proposes a kind of miniature multipath bank of filters based on LTCC and DGS, comprises SP3T switch chip, the first microwave filter, the second microwave filter and the 3rd microwave filter; First output port of switch chip, the second output port and the 3rd output port connect the first input end mouth of the first microwave filter, the second microwave filter and the 3rd microwave filter, the second input port and the 3rd input port respectively; Different closed-circuit workings is controlled by switch chip.
Further, SP3T switch chip comprises: signal input port, the first output port, the second output port, the 3rd output port, first export and select control end, control end is selected in the second output, the 3rd output selects control end, the 4th to export selection control end.
Further, first microwave filter, the second microwave filter are identical with the structure of the second microwave filter, include 50 ohm of input ports, input lead inductance, first order parallel resonance unit, second level parallel resonance unit, third level parallel resonance unit, fourth stage parallel resonance unit, level V parallel resonance unit, output lead inductance, 50 ohm of output ports, the first screen, secondary shielding layer, Z-shaped interstage coupling unit, the first grounding ports and second grounding ports.
Further, every grade of parallel resonance unit is made up of the two-layer transmission line of parallel placement; The ground floor transmission line of input lead inductance, every grade of parallel resonance unit and output lead inductance are at grade; One end of the ground floor transmission line of every grade of parallel resonance unit is all connected with the first earth terminal, and the other end is all opened a way; One end of the second layer transmission line of every grade of parallel resonance unit is all connected with the second earth terminal, and the other end is all opened a way; One end of input lead inductance is connected with the middle part of the ground floor transmission line of first order parallel resonance unit, and the other end connects and is connected with 50 ohm of input ports; One end of output lead inductance is connected with in the middle part of the ground floor transmission line of the 6th grade of parallel resonance unit, and the other end is connected with 50 ohm of output ports; Z-shaped coupling unit is positioned at the below of five parallel resonance unit, the top of the first screen, and the two ends of Z-shaped coupling unit are connected with the second earth terminal with the first earth terminal respectively.
Further, 50 ohm of input ports in the first microwave filter, the second microwave filter and the second microwave filter, input lead inductance, first order parallel resonance unit, second level parallel resonance unit, third level parallel resonance unit, fourth stage parallel resonance unit, level V parallel resonance unit, output lead inductance, 50 ohm of output ports, the first screen, secondary shielding layer, Z-shaped interstage coupling unit, the first grounding ports and second grounding ports all adopt multilayer LTCC technique to realize.
Compared with prior art, its remarkable advantage is in the present invention: (1) achieves the advantage that filter frequencies selectivity is good, passband response is smooth, transition band is precipitous, Out-of-band rejection is good, return loss is little, insertion loss is little; (2) microwave switch Insertion Loss is achieved little, the advantage that return loss is little; (3) have employed defect ground structure in structure of the present invention, make bank of filters to the suppression of high order harmonic component well; (4) volume of the present invention is little, lightweight, reliability is high, excellent electrical property, implementation structure are simple, cost is low, can realize production in enormous quantities.
Accompanying drawing explanation
Fig. 1 is the overall structure schematic diagram of the miniature multipath bank of filters that the present invention is based on LTCC and DGS.
Fig. 2 is the structural representation of median filter of the present invention.
The S parameter amplitude-versus-frequency curve figure of the first output port when Fig. 3 is the first filter place branch road conducting in emulation experiment of the present invention.
The voltage standing wave ratio schematic diagram of input port when Fig. 4 is the first filter place branch road conducting in emulation experiment of the present invention.
The S parameter amplitude-versus-frequency curve figure of the second output port when Fig. 5 is the second filter place branch road conducting in emulation experiment of the present invention.
The voltage standing wave ratio schematic diagram of input port when Fig. 6 is the second filter place branch road conducting in emulation experiment of the present invention.
The S parameter amplitude-versus-frequency curve figure of the 3rd output port when Fig. 7 is the 3rd filter place branch road conducting in emulation experiment of the present invention.
The voltage standing wave ratio schematic diagram of input port when Fig. 8 is the 3rd filter place branch road conducting in emulation experiment of the present invention.
Embodiment
Easy understand, according to technical scheme of the present invention, when not changing connotation of the present invention, one of ordinary skill in the art can imagine the numerous embodiments of the miniature multipath bank of filters the present invention is based on LTCC and DGS.Therefore, following embodiment and accompanying drawing are only the exemplary illustrations to technical scheme of the present invention, and should not be considered as of the present invention all or the restriction be considered as technical solution of the present invention or restriction.
Composition graphs 1, Fig. 2, the present invention is based on the miniature multipath bank of filters of LTCC and DGS, comprise SP3T switch chip Switch, first microwave filter Filter1, second microwave filter Filter2 and the 3rd microwave filter Filter3, the first output port RFOut1 of switch chip Switch, second output port RFOut2 and the 3rd output port RFOut3 connects the first microwave filter Filter1 respectively, the first input end mouth In1 of the second microwave filter Filter2 and the 3rd microwave filter Filter3, second input port In2 and the 3rd input port In3, different closed-circuit workings is controlled by switch chip Switch, thus realize the bank of filters of the free frequency-selecting of multichannel.
SP3T switch chip Switch comprises: signal input port RFIn, the first output port RFOut1, the second output port RFOut2, the 3rd output port RFOut3, first export and select control end V1, control end V2 is selected in the second output, the 3rd output selects control end V3, the 4th to export selection control end V4.
First microwave filter Filter1, the second microwave filter Filter2 are identical with the structure of the second microwave filter Filter2, and just the size of concrete transmission line is different, and being operated in different frequency ranges, is all have employed DGS structure.First microwave filter Filter1, second microwave filter Filter2 and the second microwave filter Filter2 includes 50 ohm of input port In, input lead inductance L in, first order parallel resonance unit, second level parallel resonance unit, third level parallel resonance unit, fourth stage parallel resonance unit, level V parallel resonance unit, output lead inductance L out, 50 ohm of output port Out, first screen DGS1 of defect ground structure, the secondary shielding layer DGS2 of defect ground structure, first grounding ports Gnd1 of Z-shaped interstage coupling unit ZL and Surface Mount structure and the second grounding ports Gnd2.
Every grade of parallel resonance unit is made up of the two-layer transmission line of parallel placement, first order parallel resonance unit is made up of two-layer transmission line L11 and L12, second level parallel resonance unit is made up of two-layer transmission line L21 and L22, third level parallel resonance unit is made up of two-layer transmission line L31 and L32, fourth stage parallel resonance unit is made up of two-layer transmission line L41 and L42, and level V parallel resonance unit is made up of two-layer transmission line L51 and L52.
Input lead inductance L in, ground floor transmission line L11, L21, L31, L41, L51 of every grade of parallel resonance unit and output lead inductance L out is at grade; One end of ground floor transmission line L11, L21, L31, L41, L51 of every grade of parallel resonance unit is all connected with the first earth terminal Gnd1, and the other end is all opened a way; One end of the second layer transmission line L12, L22, L32, L42, L52 of every grade of parallel resonance unit is all connected with the second earth terminal Gnd2, and the other end is all opened a way; One end of input lead inductance L in is connected with the middle part of the ground floor transmission line L11 of first order parallel resonance unit, and the other end connects and is connected with 50 ohm of input port In; One end of output lead inductance L out is connected with in the middle part of the ground floor transmission line L61 of the 6th grade of parallel resonance unit, and the other end is connected with 50 ohm of output port Out; Z-shaped coupling unit ZL is spatially positioned at the below of five parallel resonance unit, the top of the first screen DGS1, and the two ends of Z-shaped coupling unit ZL are connected with the second earth terminal Gnd2 with the first earth terminal Gnd1 respectively.
First microwave filter Filter1, 50 ohm of input port In in second microwave filter Filter2 and the second microwave filter Filter2, input lead inductance L in, first order parallel resonance unit, second level parallel resonance unit, third level parallel resonance unit, fourth stage parallel resonance unit, level V parallel resonance unit, output lead inductance L out, 50 ohm of output port Out, first screen DGS1, secondary shielding layer DGS2, Z-shaped interstage coupling unit ZL, first grounding ports Gnd1 and the second grounding ports Gnd2 all adopts multilayer LTCC technique to realize.Owing to being the realization of employing multilayer LTCC technique, its low-temperature co-burning ceramic material and metallic pattern sinter and form at about 900 DEG C of temperature, so have extreme high reliability and temperature stability, because structure adopts, 3 D stereo is integrated to be grounded with multilayer folding structure and outer surface metallic shield and to encapsulate, thus volume is significantly reduced.
In order to further illustrate design effect of the present invention, use the HFSS of Ansys company and the ADS software of Agilent company is analyzed the miniature multipath bank of filters that the present invention is based on LTCC and DGS, modeling and simulation, the size of each filter in the miniature multipath bank of filters of emulation is only 1.6mm × 3.2mm × 1.5mm, signal inputs from switch input terminal mouth, selected by three tunnels, carry out frequency-selecting by the filter of different branch.
Transformation parameter figure during the first filter conducting is obtained in Fig. 3, the corresponding scanning frequency of abscissa, during the first filter conducting of ordinate correspondence, 1 port is to the transformation parameter dBS (2 of 2 ports, 1), m1/m2 has marked the S21 value of difference in passband, can find out, the free transmission range of the first filter is 9 ~ 12.5GHz, Insertion Loss is maximum more than 3dB, and Insertion Loss is less;
The reflection parameters figure of 1 port when obtaining the first filter conducting in Fig. 4, the corresponding scanning frequency of abscissa, 1 port reflects parameter d BS (1 during the first filter conducting of ordinate correspondence, 1), m1/m2/m3 has marked the S11 value of difference in passband, can find out, during switch conduction Filter1, band standing internal wave is maximum more than 1.5, and band standing internal wave is less;
Transformation parameter figure during the second filter conducting is obtained in Fig. 5, the corresponding scanning frequency of abscissa, during the second filter conducting of ordinate correspondence, 1 port is to the transformation parameter dBS (2 of 2 ports, 1), m1/m2 has marked the S21 value of difference in passband, can obtain, and the free transmission range of Filter2 is 11 ~ 14GHz, Insertion Loss is maximum at 3.1dB, and Insertion Loss is less;
The reflection parameters figure of 1 port when obtaining the second filter conducting in Fig. 6, the corresponding scanning frequency of abscissa, 1 port reflects parameter d BS (1 during the second filter conducting of ordinate correspondence, 1), m1/m2/m3 has marked the S11 value of difference in passband, can find out, during switch conduction Filter2, band standing internal wave is maximum more than 1.53, and standing wave is better;
Transformation parameter figure during the 3rd filter conducting is obtained in Fig. 7, the corresponding scanning frequency of abscissa, during the 3rd filter conducting of ordinate correspondence, 1 port is to the transformation parameter dBS (2 of 2 ports, 1), m1/m2 has marked the S21 value of difference in passband, can obtain, and the free transmission range of Filter3 is 12.5 ~ 16.5GHz, Insertion Loss is maximum at 3.2dB, has less loss in passband;
The reflection parameters figure of 1 port in Fig. 8 during acquisition the 3rd filter conducting, the corresponding scanning frequency of abscissa, 1 port reflects parameter d BS (1 during the 3rd filter conducting of ordinate correspondence, 1), m1/m2/m3 has marked the S11 value of difference in passband, can obtain, in band, maximum standing wave is 1.7, and now standing wave is not fine relative to first two situation.
As can be seen from above, in the present invention, the free transmission range of the first filter is 9 ~ 12.5GHz, the free transmission range of the second filter is 11 ~ 14GHz, the free transmission range of the 3rd filter is 12.5 ~ 16.5GHz, in system passband, Insertion Loss is at about 3dB, isolation of system degree remains on below 40dB, has outstanding isolation performance.