CN101355348A - Switch type two-channel SAW filter - Google Patents
Switch type two-channel SAW filter Download PDFInfo
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- CN101355348A CN101355348A CNA200810196511XA CN200810196511A CN101355348A CN 101355348 A CN101355348 A CN 101355348A CN A200810196511X A CNA200810196511X A CN A200810196511XA CN 200810196511 A CN200810196511 A CN 200810196511A CN 101355348 A CN101355348 A CN 101355348A
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Abstract
The invention provides a switching type double channel surface acoustic wave filter, comprising two input end interdigital energy converters integrated on a piezoelectric crystal wafer, a common output end interdigital energy converter and a shielding strip between the input end interdigital energy converter and the common output end interdigital energy converter, wherein envelope lines of the two input end interdigital energy converters respectively extend from the center of a surface acoustic wave transmission channel to two ends slantingly along the interdigital conflux strip on one side, the interdigital overlapping area of the interdigital energy converter of the first input end on the center of the surface acoustic wave transmission channel is larger than the interdigital overlapped area extending to the two ends slantingly; and the interdigital overlapping area of the interdigital energy converter of the second input end on the surface acoustic wave transmission channel may be not the largest, and the interdigital overlapping area extending to the two ends slantingly is overlapped in the surface acoustic wave transmission channel of the interdigital overlapped energy converter of the first input end. By the switching type, the switching type double channel surface acoustic wave filter realizes different filter functions. The switching type double channel surface acoustic wave filter effectively reduces the occupied area of chip and easily realizes the compensation in the weighing design.
Description
Technical field
The present invention relates to band pass filter, be specifically related to be integrated in the Surface Acoustic Wave Filter on the piezoelectric crystal plate.
Background technology
Be carried in when voltage on the electrode of substrate material (for example lithium niobate monocrystal material), can in the lattice of piezoelectric crystal plate, form the machinery distortion with piezoelectric property.When voltage signal is carried on the piezoelectric crystal plate, can form surface acoustic wave in the lattice on piezoelectric crystal plate surface, this surface acoustic wave is a kind of elastic mechanical ripple that reduces rapidly with the increase of going deep into the substrate material degree of depth at the propagation of piezoelectric crystal material surface, amplitude.
Surface Acoustic Wave Filter has the characteristic of band pass filter.The realization of Surface Acoustic Wave Filter bandpass filtering function is the surface acoustic wave that forms based in the above-mentioned lattice.The basic structure of Surface Acoustic Wave Filter is to make certain thickness aluminium film on the burnishing surface with the substrate material of piezoelectric property (for example lithium niobate monocrystal material), on aluminum membranous layer, be crossed as right pectination aluminium electrode structure by photoetching process formation, on this comb-shape electrode structure, apply the signal of telecommunication, just interdigital at two comb electrodes forms surface acoustic wave, therefore this comb-shape electrode structure plays a part electroacoustic transducer, is called interdigital transducer.The excitation area of interdigital formation transducer of two comb electrodes, the comb shank portion of each interdigital finger of connection of two comb electrodes is called busbar, and signal voltage puts on two busbars of interdigitated electrodes, and each busbar is connected with external circuit by electric contact.Interdigital transducer is divided into input transducer and output transducer again: the input transducer converts the electrical signal to the surface acoustic wave signal, propagates along plane of crystal, and output transducer becomes the surface acoustic wave conversion of signals signal of telecommunication output again.Described input transducer and output transducer constitute the transmission channel of surface acoustic wave, and described transmission channel has different surface acoustic wave transmission characteristic or bandpass characteristics according to the different weights structure of interdigital transducer.
In the prior art, have switch type two-channel SAW filter, it can switch the transfer function of realizing that its surface acoustic wave transmission channel is different with the electrode of input interdigital transducer by switch.As list of references: the paper that 1992 IEEE deliver " compensation of switching mode Filter Design and second-order effects " Design of Switchable Inline Filter and Compensation of Second OrderEffects ", 1992 IEEE ULTRASONICS SYMPOOSIUM-15 ".A kind of method for designing that this paper proposes as shown in Figure 1, independently single channel filter A and A1 design at first two channels filter to be regarded as two.The acoustic transmission channel of interdigital transducer is by the outer decision of the envelope of its juxtaposition part, is TDA as the acoustic transmission channel of interdigital transducer A among Fig. 1, and the acoustic transmission channel of interdigital transducer B is TDB.Acoustic transmission channel TDA and the TDB of two interdigital transducer A and B are distinct.Wherein interdigital transducer B is design like this, design two single pass interdigital transducer A and A1 at first respectively, by with the pulse technique index addition of two interdigital transducers or subtract each other, be weighted design and obtain interdigital transducer B, as shown in Figure 1, make the width (sound aperture) of the acoustic transmission channel TDB of interdigital transducer B among Fig. 1 less than the width (sound aperture) of the acoustic transmission channel of interdigital transducer A or A1.See Fig. 2, the width of chip depend mainly on two acoustic transmission channel width TDA and TDB and, so just can dwindle chip area, reduce cost.
The shortcoming of above-mentioned method for designing is: the input interdigital transducer A of design and A1 are the interdigital juxtaposition length of mid portion big (as DA among Fig. 1 and DA1) separately, and two ends juxtaposition length is less.Since second channel B be through with two separately the input interdigital transducers of design by the addition of pulse technique index or subtract each other and obtain, in order to reduce area of chip, must make the width TDB of second channel as much as possible little, compensation space when so being weighted design is narrow and small, become difficult unusually, even can't reach designing requirement, performance of filter is degenerated.In order to reach designing requirement, can only strengthen the width of second channel B, this makes chip area increase again, and cost increases.
The content of invention
The present invention is directed to the above-mentioned shortcoming of existing switch type two-channel SAW filter, another kind of switch type two-channel SAW filter is provided, its chip area that takies is littler, and the compensation of easier realization weighting design.
Technical scheme of the present invention is as follows:
A kind of switch type two-channel SAW filter, comprise two input interdigital transducers being integrated on the piezoelectric crystal plate, shared output interdigital transducer and shielding strip between the two, described two input interdigital transducers are provided with interdigital busbar respectively; The envelope of first input interdigital transducer is from the center of its surface acoustic wave transmission channel, to the two ends diagonally extending, the diagonally extending method of the envelope of second input interdigital transducer is consistent with the diagonally extending method of first input interdigital transducer along the interdigital busbar of a side; First input interdigital transducer is greater than the interdigital overlapping region to the two ends diagonally extending in the interdigital overlapping region at its surface acoustic wave transmission channel center; Second input interdigital transducer may not be maximum in the interdigital overlapping region at its surface acoustic wave transmission channel center, and its interdigital overlapping region to the two ends diagonally extending is overlapped in the surface acoustic wave transmission channel of first input interdigital transducer.
In described two input interdigital transducers, two busbars of first input interdigital transducer connect input signal source and ground connection respectively, and are in running order all the time; Two busbars of second input interdigital transducer are connected with the diverter switch that is arranged at external circuit, diverter switch connects input signal source and ground connection respectively, make second input interdigital transducer be in work or off position, make Surface Acoustic Wave Filter realize different functions.
Its further technical scheme is:
Described two input interdigital transducers can shared centre a busbar, also the busbar that mediates separately can be electrically connected; Shared busbar is tortuous or tilts between described two input interdigital transducers, and it utilizes the part finger and carry out segmentation and connects and composes; The shared busbar of perhaps described two input interdigital transducers is near an end of output interdigital transducer, can be separated into two tilts or crooked busbar, respectively near the envelope of two input interdigital transducers, these two tilt or tortuous busbar between interdigitally disconnect and ground connection with these two described busbars; The busbar of described second input interdigital transducer one side is positioned as close to its envelope near the inclination or a tortuous end of output interdigital transducer, and described busbar should should be disconnected and ground connection by end by end interdigital and described busbar in addition;
Be provided with the metallic shield bar D that favours interdigital electrode between input interdigital transducer and output interdigital transducer, this metallic shield bar D is by external electrode ground connection; Have at least wherein busbar of an input interdigital transducer to be electrically connected with described metallic shield bar D and ground connection;
Useful technique effect of the present invention is:
Because second input interdigital transducer may not be maximum in the interdigital overlapping region at its surface acoustic wave transmission channel center, its interdigital overlapping region to the two ends diagonally extending is overlapped in the surface acoustic wave transmission channel of first input interdigital transducer, thereby chip area of the present invention is further dwindled.And interdigital of the zone that of second input interdigital transducer can being successively decreased disconnects with its busbar and is connected with shielding strip D, so make interdigital transducer B2 when being weighted design, the space of compensation becomes very big, can reach the bandpass characteristics requirement of filter at an easy rate.
Description of drawings
Fig. 1 is the schematic diagram of the Surface Acoustic Wave Filter method for designing of list of references, and the electrology characteristic addition of promptly adopted finger transducer A and interdigital transducer A1 or subtract each other obtains the schematic diagram of interdigital transducer B.
Fig. 2 is the floor map of the double-channel SAW filter that obtains by Fig. 1 method for designing.
Fig. 3 is a floor map of the present invention, and the present invention is in first transfer function operating state among the figure.
Fig. 4 is the acoustic transmission channel TDA and the equitant schematic diagram of TDB of two input interdigital transducers among the present invention.
Fig. 5 is in the schematic diagram of second transfer function operating state for the present invention.
When Fig. 6 realized first transfer function for the present invention, bandwidth was the spectrum curve figure of the band pass filter of 7.0MHz.
When Fig. 7 realized second transfer function for the present invention, bandwidth was the spectrum curve figure of the band pass filter of 8.0MHz.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is described further.
Fig. 3 is a floor map of the present invention.See Fig. 3, the present invention includes two input interdigital transducer A2 being integrated on the piezoelectric crystal plate 1 and the shielding strip D between B2, its shared output interdigital transducer C2 and input interdigital transducer and the output interdigital transducer, interdigital transducer A2 is made of the interdigital electrode that busbar 2, busbar 3 connect opposed polarity respectively, and interdigital transducer B2 is made of the interdigital electrode that busbar 3, busbar 4 connect opposed polarity respectively.Described two input interdigital transducer A2 and B2 can shared comb electrodes, and each side of two input interdigital transducers and the middle part of shared comb electrode are provided with interdigital busbar 2,4,3 respectively; Two input interdigital transducer A2 and B2 also can have two busbars respectively, and the busbar that two input interdigital transducer A2 and B2 are mediated separately is electrically connected, and replaces above-mentioned busbar 3.
Envelope 5,6 centers from its surface acoustic wave transmission channel of first input interdigital transducer A2 begin along the interdigital busbar 2 of a side to the two ends diagonally extending, and the diagonally extending method of the envelope of second input interdigital transducer B2 is consistent with the diagonally extending method of first input interdigital transducer A2; First input interdigital transducer A2 in the interdigital overlapping region 9 at its surface acoustic wave transmission channel center greater than interdigital overlapping region to the two ends diagonally extending; Second input interdigital transducer B2 may not be maximum in the interdigital overlapping region 10 at its surface acoustic wave transmission channel center, and its interdigital overlapping region to the two ends diagonally extending is overlapped in the surface acoustic wave transmission channel (sound aperture) of first input interdigital transducer A2.At this moment, the width of chip no longer be decided by two transmission channel width and, and only be decided by the transmission channel width sum of two interdigital transducer A2 and B2 core, and the transmission channel width of interdigital transducer B2 core is far smaller than the width of its acoustic transmission channel TDB (sound aperture), therefore the chip width can further dwindle, as shown in Figure 4.
The busbar 4 of second input interdigital transducer B2 one side is positioned as close to its envelope 7,8 near an inclination or the tortuous end of output interdigital transducer C2, and described busbar 4 interdigital 11 beyond should end should be disconnected by end with described busbar 4, and be connected and ground connection with metallic shield bar D, very big space is just reserved in zone beyond busbar 4 these ends like this, and this segment space can be left for and compensate use when interdigital transducer B2 does the weighting design.
Among Fig. 3, shared busbar 3 is tortuous or tilts between two input interdigital transducers, and busbar 3 carries out need utilizing the part finger when segmentation connects.
The shared busbar 3 of two input interdigital transducers is near the end of output interdigital transducer C2 among Fig. 3, can be separated into two tilts or crooked busbar (not drawing among the figure), respectively near the envelope 5,6 and 7,8 of two input interdigital transducer A2, B2, these two tilt or tortuous busbar between interdigital with these two tilt or tortuous busbar disconnects, and be connected and ground connection with metallic shield bar D, so can improve the shielding isolation performance between two input interdigital transducers and the shared output transducer C2.
The busbar 2,3 of input interdigital transducer A2 is connected with external electrode by contact 42,43 respectively.5,6 is the envelope of the interdigital lap of input interdigital transducer A2,7,8 is the envelope of the juxtaposition part of input interdigital transducer B2, surface acoustic wave is excited by the interdigital electrode of the juxtaposition in two envelopes, the interdigital surface acoustic wave that do not excite beyond the envelope.The busbar 3,4 of input interdigital transducer B2 is connected with external electrode by contact 43,44.C2 is an output interdigital transducer, connects different interdigital electrodes respectively by busbar 12,13, and is connected with external electrode by contact 45,46.See Fig. 3, between input interdigital transducer and output interdigital transducer, be provided with the metallic shield bar D that favours interdigital electrode, this metallic shield bar D is by external electrode ground connection, have at least wherein busbar of an input interdigital transducer to be electrically connected with described metallic shield bar D and ground connection, busbar 2 is electrically connected with described metallic shield bar D and ground connection among Fig. 3.
As shown in Figure 3, because busbar 2 is connected also ground connection with shielding strip D, when input signal inserted contact 43,44 simultaneously, two busbars 4,3 of input interdigital transducer B2 had identical current potential, input interdigital transducer B2 does not excite surface acoustic wave, is in off position.Two busbars 2,3 of input interdigital transducer A2 have different current potential (contact 42 ground connection), excite surface acoustic wave, and are in running order.Reception (output) transducer C2 receives the surface acoustic wave from interdigital transducer A2, and is converted to signal of telecommunication output, realizes first transfer function.
As shown in Figure 5, when input signal inserts contact 43, and contact 42,44 is respectively during ground connection, and two busbars 4,3 of input interdigital transducer B2 have different current potentials, and input interdigital transducer B2 excites surface acoustic wave, and is in running order.Simultaneously, two busbars 2,3 of input interdigital transducer A also have different current potentials, excite surface acoustic wave, and are in running order.Reception (output) transducer C2 receives the surface acoustic wave from interdigital transducer A2 and input interdigital transducer B2 simultaneously, and is converted to signal of telecommunication output, realizes second transfer function.
In above-mentioned two input interdigital transducers, two busbars of first input interdigital transducer A2 connect input signal source and ground connection respectively, and are in running order all the time; Two busbars of second input interdigital transducer B2 can be connected with the diverter switch that is arranged at external circuit, diverter switch connects input signal source and ground connection respectively, make second input interdigital transducer be in work or off position, make Surface Acoustic Wave Filter realize different functions.
Below be one embodiment of the present of invention
The embodiment of the invention is the surface acoustic wave intermediate-frequency filter of digital television receiver, and its centre frequency is 36.0MHz.Two transfer functions realizing are respectively two band pass filters of bandwidth 7.0MHz, 8.0MHz.
As shown in Figure 3, when input signal inserted contact simultaneously at 43,44 o'clock, two busbars 4 of input interdigital transducer B2 have identical current potential with 3, and input interdigital transducer B2 does not excite surface acoustic wave, is in off position.Two busbars 2 of input interdigital transducer A2 have different current potential (contact 42 ground connection) with 3, excite surface acoustic wave, and are in running order.Reception (output) transducer C2 receives the surface acoustic wave from interdigital transducer A2, and is converted to signal of telecommunication output, realizes first transfer function, and promptly bandwidth is the band pass filter of 7.0MHz, and its bandpass characteristics figure as shown in Figure 6.
As shown in Figure 5, when input signal inserts 43, and during contact 44,42 ground connection, two busbars 4 of input interdigital transducer B2 have different current potentials with 3, and input interdigital transducer B2 excites surface acoustic wave, and is in running order.Simultaneously, two busbars 2 of input interdigital transducer A2 also have different current potentials with 3, excite surface acoustic wave, in running order, reception (output) transducer C2 receives the surface acoustic wave from interdigital transducer A2 and input interdigital transducer B2 simultaneously, and is converted to signal of telecommunication output, realizes second transfer function, be that bandwidth is the band pass filter of 8.0MHz, its bandpass characteristics figure as shown in Figure 7.
The finger number of two input interdigital transducers of the embodiment of the invention is all 260, and the finger number of public output (reception) transducer is 19, and chip area is 11x2.2mm.Among Fig. 4, TDA is 0.85mm, and TDB is 1.12mm, and TDA and TDB lap are that 0.65mm. that is to say, by the present invention, can reduce by nearly 30% area.
Claims (8)
1. switch type two-channel SAW filter, comprise two input interdigital transducers that are integrated on the piezoelectric crystal plate, shared output interdigital transducer and shielding strip between the two, described two input interdigital transducers are provided with interdigital busbar respectively, it is characterized in that: the envelope of first input interdigital transducer is from the center of its surface acoustic wave transmission channel, to the two ends diagonally extending, the diagonally extending method of the envelope of second input interdigital transducer is consistent with the diagonally extending method of first input interdigital transducer along the interdigital busbar of a side; First input interdigital transducer is greater than the interdigital overlapping region to the two ends diagonally extending in the interdigital overlapping region at its surface acoustic wave transmission channel center; Second input interdigital transducer may not be maximum in the interdigital overlapping region at its surface acoustic wave transmission channel center, and its interdigital overlapping region to the two ends diagonally extending is overlapped in the surface acoustic wave transmission channel of first input interdigital transducer.
2. according to the described switch type two-channel SAW filter of claim 1, it is characterized in that: in described two input interdigital transducers, two busbars of first input interdigital transducer connect input signal source and ground connection respectively, and are in running order all the time; Two busbars of second input interdigital transducer are connected with the diverter switch that is arranged at external circuit, diverter switch connects input signal source and ground connection respectively, make second input interdigital transducer be in work or off position, make Surface Acoustic Wave Filter realize different functions.
3. according to claim 1 or 2 described switch type two-channel SAW filters, it is characterized in that: the busbar that described two input interdigital transducers can shared centre also can be electrically connected the busbar that mediates separately.
4. according to the described switch type two-channel SAW filter of claim 3, it is characterized in that: shared busbar is tortuous or tilts between described two input interdigital transducers, and it utilizes the part finger and carry out segmentation and connects and composes.
5. according to the described switch type two-channel SAW filter of claim 1, it is characterized in that: the shared busbar of described two input interdigital transducers is near an end of output interdigital transducer, can be separated into two tilts or crooked busbar, respectively near the envelope of two input interdigital transducers, these two tilt or tortuous busbar between interdigitally disconnect and ground connection with these two described busbars.
6. according to the described switch type two-channel SAW filter of claim 1, it is characterized in that: the busbar of described second input interdigital transducer one side is positioned as close to its envelope near the inclination or a tortuous end of output interdigital transducer, and described busbar should should be disconnected and ground connection by end by end interdigital and described busbar in addition.
7. according to the described switch type two-channel SAW filter of claim 1, it is characterized in that: be provided with the metallic shield bar D that favours interdigital electrode between input interdigital transducer and output interdigital transducer, this metallic shield bar D is by external electrode ground connection.
8. according to the described switch type two-channel SAW filter of claim 7, it is characterized in that: have at least wherein busbar of an input interdigital transducer to be electrically connected with described metallic shield bar D and ground connection.
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| CN200810196511XA CN101355348B (en) | 2008-09-08 | 2008-09-08 | Switch type two-channel SAW filter |
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| CN200810196511XA CN101355348B (en) | 2008-09-08 | 2008-09-08 | Switch type two-channel SAW filter |
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| CN101355348B CN101355348B (en) | 2010-12-08 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888221A (en) * | 2010-07-02 | 2010-11-17 | 无锡市好达电子有限公司 | Multi-bus bar |
| CN102904548A (en) * | 2012-10-11 | 2013-01-30 | 无锡市好达电子有限公司 | Highly-shielding surface acoustic wave filter |
| CN107769752A (en) * | 2017-11-17 | 2018-03-06 | 中电科技集团重庆声光电有限公司 | A kind of multiple channel acousto surface filtering module |
| CN112805593A (en) * | 2018-09-17 | 2021-05-14 | 臻迪科技股份有限公司 | Transducer device, sonar module, and control method therefor |
| CN115632620A (en) * | 2022-12-22 | 2023-01-20 | 成都嘉纳海威科技有限责任公司 | Three-channel amplification and filtering multifunctional chip |
-
2008
- 2008-09-08 CN CN200810196511XA patent/CN101355348B/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888221A (en) * | 2010-07-02 | 2010-11-17 | 无锡市好达电子有限公司 | Multi-bus bar |
| CN101888221B (en) * | 2010-07-02 | 2012-11-21 | 无锡市好达电子有限公司 | Multi-bus bar |
| CN102904548A (en) * | 2012-10-11 | 2013-01-30 | 无锡市好达电子有限公司 | Highly-shielding surface acoustic wave filter |
| CN107769752A (en) * | 2017-11-17 | 2018-03-06 | 中电科技集团重庆声光电有限公司 | A kind of multiple channel acousto surface filtering module |
| CN112805593A (en) * | 2018-09-17 | 2021-05-14 | 臻迪科技股份有限公司 | Transducer device, sonar module, and control method therefor |
| CN115632620A (en) * | 2022-12-22 | 2023-01-20 | 成都嘉纳海威科技有限责任公司 | Three-channel amplification and filtering multifunctional chip |
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| CN101355348B (en) | 2010-12-08 |
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