CN100547919C - Elastic surface acoustic wave resonator and communicator - Google Patents
Elastic surface acoustic wave resonator and communicator Download PDFInfo
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- CN100547919C CN100547919C CNB2006100679766A CN200610067976A CN100547919C CN 100547919 C CN100547919 C CN 100547919C CN B2006100679766 A CNB2006100679766 A CN B2006100679766A CN 200610067976 A CN200610067976 A CN 200610067976A CN 100547919 C CN100547919 C CN 100547919C
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Abstract
A kind of elastic surface acoustic wave resonator, on its piezoelectric substrate (19), possessing has: IDT electrode (1); Reflector electrode (2), the two ends of the main conduction orientation (F) of the elastic surface wave of itself and this IDT electrode (1) are in abutting connection with configuration; And auxiliary reflector electrode (3), on the straight line after it is positioned at the bus electrode (12a) of described IDT electrode (1) supposed to prolong, and on the position everywhere in the outside of described reflector electrode (2), the direction repeatedly (G) that makes repeatedly electrode (14b) is tilted configuration towards described IDT electrode (1).
Description
Technical field
The present invention relates to improve the elastic surface acoustic wave resonator (Surface Acoustic WaveResonator) of Q, improved the acoustic surface wave filter (Surface AcousticWave Filter) that inserts loss, improved the elastic surface wave duplexer (Surface Acoustic Wave Duplexer) of isolated (isolation) characteristic and insertion loss and electric durability simultaneously, and the communicator that uses these acoustic surface wave filters, elastic surface wave duplexer and elastic surface acoustic wave resonator.
Such elastic surface acoustic wave resonator, acoustic surface wave filter, elastic surface wave duplexer are generically and collectively referred to as " acoustic surface wave element ".Acoustic surface wave element is widely used in moving communicating field, for example as the RF section of mobile phone and the filter of IF section.
Background technology
In recent years, as element such as the filter of the electronic instrument that utilizes electric wave, delay line, oscillators, often adopt the acoustic surface wave element of small-sized, light weight, interrupting performance sensitivity.
A kind of as acoustic surface wave element, known have the elastic surface acoustic wave resonator of a plurality of 1 terminals to constituting, directly the ladder shape acoustic surface wave filter that becomes ladder (ladder) shape to connect side by side.
Usually, by the elastic surface acoustic wave resonator of 1 terminal to constituting, shown in figure 32, by comprising the forming in abutting connection with the reflector electrode 2 of configuration of both sides that electrode that bus electrode 12a and electrode refer to 13 IDT (InterDigital Transducer) electrode 1 and be positioned at the main direction of propagation of the elastic surface wave that is inspired by IDT electrode 1 refers to repeatedly direction with IDT electrode 1.
Because ladder shape acoustic surface wave filter realized miniaturization, and few in the passband internal loss, the outer decay of passband rapidly, so be widely used as the filter of the RF frequency band of mobile phone etc.
By transmitting and receiving 2 so trapezoidal acoustic surface wave filters of both sides use, can constitute antenna diplexer (duplexer).
So-called duplexer is the high-frequency unit that has frequency band (as the high frequency side frequency band) the signal divided function of frequency band (as the lower frequency side frequency band) signal of emitting side and receiver side.
Usually the emission that is added in duplexer surpasses 1W with the power on the filter, but constituting emission can not be completely enclosed within the elastic surface acoustic wave resonator with the elastic surface wave that the IDT electrode of the elastic surface acoustic wave resonator of filter inspires, leak into elastic surface acoustic wave resonator and be transmitted to outward on the piezoelectric substrate, be configured the IDT electrode reception that receives with the elastic surface acoustic wave resonator of filter.Because the elastic surface wave of these leakages is converted into electronic signal again, causes leaking into emission with in the filter to the part of the signal of antenna terminal transmission, thereby cause the S/N of received signal to worsen than (signal to noise ratio) from the input terminal of launching with filter.This is called " isolated (isolation) " from the input terminal of launching with filter to the leakage power ratio that receives with filter
In recent years, communication system is not only more strict to the requirement of specification, also urgently craves for the duplexer of isolation performance good (leakage power is than little).
In addition, owing to the further high performance along with communication equipment, the components number that constitutes communication equipment increases, and therefore frequent existence is to the miniaturization requirement of element.
Here the reason that elastic surface wave is leaked into the elastic surface acoustic wave resonator outside describes.
By the elastic surface wave that the IDT electrode inspires, general court propagates with the direction of the longitudinally orthogonal that electrode refers to, this direction is called the main direction of propagation.If electrode refers to it is to be the perfect condition with indefinite length along longitudinally, only the elastic surface wave of propagating to the main direction of propagation is excited, but the element in the reality has limited size, and therefore the actual elastic surface wave that is excited comprises the composition of overflowing from the main direction of propagation.
Existing elastic surface acoustic wave resonator shown in figure 32, the length of the longitudinally of the reflector electrode 2 at the two ends of IDT electrode 1, because form roughly the same size with IDT electrode 1 longitudinally, so reflector electrode 2 can not reflect efficiently to the composition of overflowing from the main direction of propagation, causes leaking into from the composition of overflowing in the main direction of propagation outside of elastic surface acoustic wave resonator.
In addition, the elastic surface wave that is excited by IDT electrode 1, contain a plurality of frequency contents, but because reflector electrode 2 becomes best for the reflection efficiency that makes certain frequency in the frequency content that is excited by IDT electrode 1 usually, to the cycle of electrode (also being called gate electrode) is designed repeatedly, the elastic surface wave of other frequency device that can not be reflected reflects expeditiously, and leaks into the outside of elastic surface acoustic wave resonator.
In addition, the communication mode that exists in the communication mode of the existence on the main round in the elastic surface acoustic wave resonator and the bus electrode 12a can in conjunction with situation under, electrode refers to that the elastic surface wave that is excited on the crossover sites leaks to bus electrode 12a, because the top of bus electrode 12a does not have sealed elastic surface wave structure, so surface wave just from the end leakage of bus electrode to the resonon outside (for example, with reference to J.V.Knuuttila, J.Koskela, P.T.Tikka, and M.M.Salomaa, 1999IEEE Ultrasonics Sympo., P83).
Thus and thus leak into the elastic surface wave of elastic surface acoustic wave resonator outside, cause above-mentioned such problem.Such leakage is not taken as problem before for duplexer, but owing to the strict demand to performance in recent years becomes problem.
(Patent Document 1) opens flat 6-9229 communique in fact
(Non-Patent Document 1) matsuda acute hearing, vegetarian rattan health it, control in the river, Gong Benjing rule, " elastic wave observation is to the improvement of SAW acoustic surface wave element characteristic ", the 33rd the pre-original text collection of EM symposium, on May 20th, 2004, P.77-82
→J.Tsutsumi，S.Inoue，and?Y.Iwamoto，”Extremly?Low-Loss?SAWFilter?and?Its?Application?to?Antenna?Duplexer?for?The?1.9GHz?PCSFull-Band”，Proc.IEEE?International?Frequency?Control?Sympo.pp.861-867，(2003)
(Non-Patent Document 2) J.V.Knuuttila, J.Koskela, P.T.Tikka, andM.M.Salomaa, 1999IEEE Ultrasonics Sympo., P83
Summary of the invention
Purpose of the present invention by preventing that elastic surface wave from leaking into the elastic surface acoustic wave resonator outside, realizes having the elastic surface acoustic wave resonator of high Q exactly.
In addition, the objective of the invention is to, the elastic surface acoustic wave resonator of the application of the invention is realized miniaturization and is inserted the low acoustic surface wave filter of loss.
In addition, the objective of the invention is to, the elastic surface acoustic wave resonator of the application of the invention, realization miniaturization and isolated characteristic good, insertion are lost low, and electric durability excellent elasticity surface wave duplexer.
In addition, the objective of the invention is to, elastic surface acoustic wave resonator of the application of the invention and acoustic surface wave filter and elastic surface wave duplexer provide low power consumption, communication quality excellent communications device.
Elastic surface acoustic wave resonator of the present invention, has piezoelectric substrate, with be formed on the described piezoelectric substrate, has bus electrode IDT electrode, with be formed on the described piezoelectric substrate, with the two ends of the main conduction orientation of the elastic surface wave of described IDT electrode in abutting connection with and the reflector electrode of configuration, with be formed on the described piezoelectric substrate, has the electrode that is concatenated to form, position in the outside of described reflector electrode, the hypothesis that is configured in the bus electrode of described IDT electrode prolongs the auxiliary reflector electrode on the straight line.
Elastic surface acoustic wave resonator according to this structure, the elastic surface wave that direction beyond the main direction of propagation of the elastic surface wave of described IDT electrode is leaked by described auxiliary reflector electrode, with the elastic surface wave reflection of leaking from described bus electrode, because can be closed in described elastic surface acoustic wave resonator inside, can realize that elastic surface wave leaks less, the elastic surface acoustic wave resonator of high Q.
Described auxiliary reflector electrode is preferably formed direction repeatedly for the described electrode that is concatenated to form (Fig. 1, shown in Figure 11 G), and is relative with described IDT electrode.
Particularly be preferably the angle θ that direction repeatedly that the electrode of the direction repeatedly of the electrode that is concatenated to form of described auxiliary reflector electrode and described IDT electrode refers to forms and surpass 0 degree, be lower than 20 degree.
In addition, the quantity of the auxiliary reflector electrode of described each IDT electrode is not defined, and for example can be configured on the position everywhere in the oblique outside of described reflector electrode yet.
Also have, described auxiliary reflector electrode also can be to have 2 bus electrodes, and two ends of the described electrode that is concatenated to form of above-mentioned auxiliary reflector electrode are connected on the described bus electrode, form so-called ladder shape electrode.
In addition, described auxiliary reflector electrode also can be that an end of the described electrode that is concatenated to form has on electrical characteristics by the electrode of the interdigitated electrode structure of open shape.
In addition, described auxiliary reflector electrode also can be that two ends of the described electrode that is concatenated to form have on electrical characteristics by open electrode
In addition, described auxiliary reflector electrode also can be to have 2 bus electrodes, has to make that upwardly extending electrode refers to the IDT electrode of the shape that meshes in approximate right angle side from described bus electrode.
In addition, in described formation, the spacing of auxiliary reflector electrode can be made as different with the spacing of reflector electrode.Like this, can make described auxiliary reflector electrode under the wavelength different with described reflector electrode, design improves reflection efficiency, can significantly suppress the leakage in the elastic surface wave direction elastic surface acoustic wave resonator outside.
In addition, according to elastic surface acoustic wave resonator of the present invention, the spacing of described auxiliary reflector electrode can be made as different with the spacing of described IDT electrode.So-called " spacing " is meant that one electrode refers to the center distance that the electrode adjacent with it refers to.Thus and thus, can make the resonance of not wanting that suppresses to take place between auxiliary reflector electrode and the IDT electrode become possibility, can obtain the few elastic surface acoustic wave resonator of parasitic resonance.
In addition, by between 2 auxiliary reflector electrodes in the described reflector electrode outside, form the second auxiliary reflector electrode, the surface wave that described reflector electrode fails to reflect fully can be reflected back, be closed in elastic surface acoustic wave resonator inside, so just can realize the elastic surface acoustic wave resonator of the high Q that the leakage of elastic surface wave is few.
Also have, can also fuse described second auxiliary reflector electrode and auxiliary reflector electrode, just can further reflect the elastic surface wave of omitting between described second auxiliary reflector electrode and the described auxiliary reflector electrode, it is closed in elastic surface acoustic wave resonator inside, thereby is more increased the resonon of Q.In addition, because the described second auxiliary reflector electrode is equated with the current potential of described auxiliary reflector electrode, so can prevent because Jiao that piezoelectric substrate has is electrical, the destruction that the trickle electrode that possible electric spark causes takes place is arranged between the different part of current potential, and can obtain the elastic surface acoustic wave resonator of high Q.
In addition, according to the acoustic surface wave filter that has used elastic surface acoustic wave resonator of the present invention, owing to possessed the elastic surface acoustic wave resonator of high Q, in addition, because can prevent to use in acceptance with the elastic surface wave of filter leakage the combination of filter from emission, so emission can be contained on the piezoelectric substrate with filter is real with filter and reception, make acoustic surface wave filter can realize miniaturization, and reduce and insert loss.
In addition, according to the elastic surface wave duplexer that has used elastic surface acoustic wave resonator of the present invention, use filter region with filter region with receiving owing on piezoelectric substrate, possess emission, by described elastic surface acoustic wave resonator being arranged at least one of described emitting area or described receiving area, can obtain miniaturization, and have good isolated characteristic, insert little, the anti-electrical performance excellent elasticity surface wave duplexer of loss.
And, according to the communicator that has possessed elastic surface wave duplexer of the present invention, owing to reduced the insertion loss of filter, input power required when obtaining identical power output is reduced, can reduce the power consumption of power amplifier, so that suppress to consume the communicator of electric power and be achieved.In addition, because the miniaturization of this elastic surface wave duplexer can ensure the assembling area of other parts, thereby realize high performance communicator.And, can obtain high speech quality because have very high isolated characteristic.
Above-mentioned among the present invention and other advantage, feature and effect are with reference to accompanying drawing and give clear and definite in the explanation of described execution mode thereafter.
Description of drawings
Fig. 1 is the vertical view of the execution mode of elastic surface acoustic wave resonator of the present invention.
Fig. 2 be acoustic surface wave element of the present invention an example the elastic surface wave duplexer overlook sketch map.
Fig. 3 is the ideograph that an end is the open auxiliary reflector electrode of electrical characteristics.
Fig. 4 is the ideograph that two ends are the open auxiliary reflector electrode of electrical characteristics.
Fig. 5 is the schematic diagram of other execution mode of elastic surface acoustic wave resonator of the present invention.
Fig. 6 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Fig. 7 is the schematic diagram of other other execution mode of the elastic surface acoustic wave resonator of invention.
Fig. 8 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Fig. 9 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 10 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 11 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 12 be acoustic surface wave element one example of the present invention the elastic surface wave duplexer overlook sketch map.
Figure 13 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 14 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 15 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 16 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 17 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 18 is the schematic diagram of other other execution mode of elastic surface acoustic wave resonator of the present invention.
Figure 19 is the sketch map of overlooking of existing elastic surface wave duplexer.
Figure 20 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 21 is the curve chart in order to the impedance operator of the elastic surface acoustic wave resonator that effect of the present invention is described.
Figure 22 is the curve chart of the antiresonance resistance of the elastic surface acoustic wave resonator made in the embodiments of the invention of expression.
Figure 23 is the curve chart of the passband characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 24 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 25 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 26 is the curve chart of expression in order to the impedance operator of elastic surface acoustic wave resonator that effect of the present invention is described.
Figure 27 is the curve chart of the antiresonance resistance of the elastic surface acoustic wave resonator made in the embodiments of the invention of expression.
Figure 28 is the curve chart of the passband characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 29 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 30 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 31 is the curve chart of the isolated characteristic of the elastic surface wave duplexer made in the embodiments of the invention of expression.
Figure 32 is the vertical view of the existing elastic surface acoustic wave resonator of expression.
Embodiment
Below, the embodiment to acoustic surface wave element of the present invention is elaborated with reference to chart.And on position same on the drawing the identical symbol of mark.In addition, to the size of each electrode and interelectrode distance etc., the perhaps radical that refers to of electrode and at interval etc., owing to illustrated in order to describe, so shown in being not limited on the figure. model utility
Figure 1 shows that the vertical view of elastic surface acoustic wave resonator.
This elastic surface acoustic wave resonator forms the element of a plurality of electrodes of being made up of metallic film on an interarea of piezoelectric substrate (with reference to Fig. 2 " 19 "), the electrode that is formed is an IDT electrode 1, reflector electrode 2 and auxiliary reflector electrode 3 etc.
Also have, auxiliary reflector electrode 3 four positions that the position is not limited to the outside of reflector electrode 2 are set.Also can only be arranged on in described four positions, also can be arranged on two or three positions.Even be arranged on one～three position, also can prevent elastic surface wave to external leaks, the effect that makes the present invention improve Q is achieved.
In not having the existing structure (Figure 32) of auxiliary reflector electrode 3, also exist from the elastic surface wave of reflector electrode 2 to external leaks.This is because because reflector electrode 2 is to be made of single electrode spacing, can will be leaked by the wavelength elastic surface wave in addition that this spacing reflects.
In addition, also has the situation of leaking elastic surface wave from the bus electrode 12a of IDT electrode 1.When the elastic surface wave that leaks out when communication mode from the bus electrode 12b of reflector electrode 2 combines, the result causes elastic surface wave to go out from the end leakage of bus electrode 12b.
Therefore,, can make the elastic surface wave reflection of leaking towards oblique θ angular direction, reduce the leakage of energy from main direction of propagation F by forming auxiliary reflector electrode 3 as shown in Figure 1.
So, can further improve the Q value of elastic surface acoustic wave resonator, and the insertion of the acoustic surface wave filter that is improved loss, improve the effects such as isolation performance of elastic surface wave duplexer.
Fig. 2 is the surface modes figure that the emission of the elastic surface acoustic wave resonator of the structure that has used Fig. 1 is formed on the elastic surface wave duplexer on the same piezoelectric substrate 19 with filter and receiving filter.Among Fig. 2, the first half represents that emission use filter, the latter half to represent that reception uses filter.
From the signal of emission, behind 3 elastic surface acoustic wave resonators in upright arrangement by being combined into ladder shape and 2 elastic surface acoustic wave resonators arranged side by side, from lead-out terminal 16 outputs with input terminal 15 input of filter.
In addition, from receiving signal with input terminal 17 inputs of filter, behind 2 elastic surface acoustic wave resonators in upright arrangement by ladder shape combination of interactions and 3 elastic surface acoustic wave resonators arranged side by side from lead-out terminal 18 outputs.
In addition, use on the elastic surface acoustic wave resonator separately of filter, added, form the elastic surface wave structure that reduces from the oblique leakage in the main direction of propagation by described auxiliary reflector electrode 3 in emitting side and reception.
In addition, be provided with ring electrode 14 on the piezoelectric substrate 19, be contained on the real dress substrate (not shown) aeroseal and use but this ring electrode 14 is used for a piezoelectric substrate 19 usefulness upside-down mounting chip methods.Even experiment showed, to have this ring electrode 14 as can be known, also almost can't prevent the surperficial wave propagation of revealing from elastic surface acoustic wave resonator.
In the structure of Fig. 2, particularly constitute emission with on the elastic surface acoustic wave resonator in upright arrangement in the elastic surface acoustic wave resonator of filter, use formation of the present invention will improve effect.
This is because be applied in emission and can penetrate elastic surface acoustic wave resonator in upright arrangement with the forceful electric power signal on the filter, but the high-intensity surface wave that inspire this moment can be sealed effectively by the present invention.
On the other hand, receiving with using on the resonon of filter under the situation of elastic surface acoustic wave resonator of the present invention, from the elastic surface wave of emission, be used to receive auxiliary reflector electrode 3 reflections with the elastic surface acoustic wave resonator arranged side by side of filter with the elastic surface acoustic wave resonator leakage in upright arrangement of filter.The result causes constituting reception with receiving the difficulty that becomes on the IDT electrode 1 of the elastic surface acoustic wave resonator arranged side by side of filter, and the effect of improving isolation performance is arranged.
Also have, can make the spacing of gate electrode 14b of auxiliary reflector electrode 3 different with the spacing of the gate electrode 14a of reflector electrode 2.
For example, by making the spacing of emission with the gate electrode 14b of the auxiliary reflector electrode 3 of the elastic surface acoustic wave resonator that uses on the filter, refer to that with the electrode that receives with the IDT electrode 1 of the elastic surface acoustic wave resonator that uses on the filter 13 spacing cooperates, can make the isolated characteristic raising of frequency acceptance band.Reason is, the elastic surface wave of the wavelength of the frequency acceptance band that reflector electrode 2 fails to reflect is fully reflected by auxiliary reflector electrode 3, leaking be closed in emission with in the elastic surface acoustic wave resonator of filter, so the elastic surface wave of frequency acceptance band can not appear in.
And, on the gate electrode 14b of auxiliary reflector electrode 3, also can constitute by a plurality of different spacings mixing.So just be not limited to specific frequency band, can on wider frequency band, be suppressed the surface wave that leaks from acoustic surface wave element, thus the Q of raising elastic surface acoustic wave resonator.In this case, the spatial arrangements mode of a plurality of spacings is particular importance not, can freely set.
In addition, described IDT electrode 1 among Fig. 1 etc., represented with on one side bus electrode 12a on the electrode that forms refer to form on the bus electrode 12a of another side at the position that 13 top is relative the situation of short simulation electrode 8, thus and thus, because can make the communication mode of main round be difficult to combine with the communication mode of bus electrode, so can reduce main round from elastic surface acoustic wave resonator by the elastic surface wave of bus electrode, can improve the Q of elastic surface resonon to external leaks.And use such elastic surface acoustic wave resonator to constitute in the filter, can make and insert the low filter of loss, and it is also higher with the isolated characteristic that receives the duplexer that constitutes with filter field with filter field to be provided with emission on same substrate.
Also have, among Fig. 1 etc. as the structure of auxiliary reflector electrode 3, used and made gate electrode 14 carry out the ladder shape electrode (short circuit reflector) of electrical short two ends, but be not limited to this form, even for example two ends or an end are made the open shape of electrical characteristics (open reflector), can improve its isolated characteristic equally.
Figure 3 shows that the example that an end is carried out the open open reflector of electrical characteristics, Figure 4 shows that the example that two ends is carried out the open open reflector of electrical characteristics.
In addition, the shape of auxiliary reflector electrode 3 also can be the shape that refers to mutual engagement (IDT type reflector) as IDT electrode electrode.This structure will use drawing to be elaborated in the back.
Also have, the shape of auxiliary reflector electrode 3 be can't help the electrode of rectilinear form and is referred to that the gate electrode that constitutes constitutes, but by the arc with certain curvature or curl or crooked shape, or is that the gate electrode that shape such as trapezoidal constitutes constitutes.Like this, the elastic surface wave that can leak in angular range internal reflection widely, thus can obtain the Q value of bigger raising resonon, improve the insertion of filter and lose, improve the effects such as isolation performance of duplexer.
In the elastic surface acoustic wave resonator of the present invention, can use monocrystalline lithium tantalate, lithium niobate monocrystal or lithium tetraborate single crystal etc. as the material of piezoelectric substrate.
In addition, for IDT electrode reflector electrode and auxiliary reflector electrode, can use aluminium, aluminium alloy, copper, copper alloy, gold, billon, tantalum, tantalum alloy or by the stacked film of these material stratification, and layer or the stacked film formed by materials such as these materials and titanium, chromium, as the film build method of these stacked films, can use methods such as spraying plating or electron beam evaporation plating.
As the formulation pattern (patterning) of IDT electrode reflector electrode and auxiliary reflector electrode, generally after the electrode film film forming, carry out photoetch, carry out rie (Reactive Ion Etching) or wet etching then.Or before the electrode film film forming, on piezoelectric substrate, coat after the shape that light-sensitive emulsion carries out IDT electrode that photoetching process form to wish and reflector electrode etc., with monofilm or the stacked film film forming that materials such as above-mentioned aluminium are formed, also can carry out thereafter with resist will be on unwanted part the monofilm of film forming and the removal operation that stacked film is removed one by one.
Below, the variation of the electrode shape that is formed on the elastic surface acoustic wave resonator on the piezoelectric substrate is described.
As shown in Figure 5, also can with the opposition side adjoining position of the IDT electrode 1 of reflector electrode 2 on, configuration has the second auxiliary reflector electrode 4 of gate electrode 14c.
Because the second auxiliary reflector electrode 4, along referring to vertical substantially direction with the electrode of IDT electrode 1, promptly the main direction of propagation F of aforesaid elastic surface wave goes up and propagates, and can make can not be fully by the elastic surface wave reflection of first reflector electrode, 2 reflections.
The spacing of the gate electrode 14c of the second auxiliary reflector electrode 4, preferably the spacing with the gate electrode 14a of reflector electrode 2 is different, and thus and thus, the elastic surface wave that can make reflector electrode 2 fail to reflect reflects efficiently.
Also have, among Fig. 5 the second auxiliary reflector electrode 4 is expressed as the ladder shape electrode of forming by bus electrode and gate electrode (short circuit reflector), even but refer to the IDT electrode (IDT type reflector) formed by bus electrode and electrode, also can only form by gate electrode (open reflector).
In addition, making a plurality of different spacing mix formation on the gate electrode 14c of this second auxiliary reflector electrode 4 also can.So,, can suppress from the elastic surface wave of elastic surface acoustic wave resonator leakage on the frequency band widely not only at specific frequency band, thus the Q value of raising elastic surface resonon.In this case, the spatial arrangements of a plurality of spacings is unimportant, can freely set.
In addition, as shown in Figure 6, also auxiliary reflector electrode 3 and the second auxiliary reflector electrode, the 4 usefulness coupling parts 5 that adjoin each other can be connected to form one.So, because the current potential of the auxiliary reflector electrode 3 and the second auxiliary reflector electrode 4 is equated, so because Jiao that piezoelectric substrate has electrically, the caused destruction of the discharge that takes place between the part of different potentials can be prevented, and the elastic surface acoustic wave resonator of high Q can be realized having trickle electrode.
In addition, under the situation that auxiliary reflector electrode 3 and the second auxiliary reflector electrode 4 are connected to form one, the structure of connection can be of all kinds.For example also can will after prolonging, the part former state that exists relatively on Fig. 5 connect originally as shown in Figure 6.
Also have, as shown in Figure 7, also the gate electrode 14b of auxiliary reflector electrode 3 and the gate electrode 14c of the second auxiliary reflector electrode 4 can be prolonged back formation one.At this moment, be provided with for the reflector bus electrode 15 that makes the gate electrode short circuit also can, be not provided with as shown in Figure 8 and also can.
In addition, as shown in Figure 9, also can make the structure that gate electrode 14d is set in the field that is equivalent between the auxiliary reflector electrode 3 and the second auxiliary reflector electrode 4.By using such structure, can make from the surface wave that leaks between the auxiliary reflector electrode 3 and the second auxiliary reflector electrode 4 and better reflect, can make it be closed in elastic surface acoustic wave resonator inside, thereby obtain the elastic surface acoustic wave resonator of higher Q.
In above structure, structure particularly shown in Figure 7 and structure shown in Figure 9 are because can be provided with only gate electrode spacing, so all favourable to all directions.
In addition, the shape of the second auxiliary reflector electrode 4 be can't help the electrode of rectilinear form and is referred to that the gate electrode that constitutes constitutes, but by the arc with certain curvature or curl or crooked shape, or is that the gate electrode that shape such as trapezoidal constitutes constitutes.So, the elastic surface wave that can leak in the reflection of angular range widely, thus can reach the Q value that improves elastic surface acoustic wave resonator better, improve the insertion of filter and lose, improve the effects such as isolation performance of duplexer.
Also have, as shown in figure 10, replace the reflector electrode with cuboid profile 2 shown in Figure 1, the bus electrode 12b that also can use reflector electrode tilts to IDT electrode 1, and makes the reflector electrode 2 ' of shape of end flexing of the gate electrode 14a of reflector electrode.
In addition, the reflector electrode 2 ' shown in Figure 10 is the shape of flexing, also can be the shape of smooth curved.
By forming such flexing or crooked shape, the elastic surface wave that leaks from the direction of IDT electrode 1 beyond the main direction of propagation of elastic surface wave just can be obtained better effect by the reflector electrode 2 ' reflection of flexing or curved shape.
Figure 11 shows that to have replaced the auxiliary reflector electrode 3 among Fig. 1, disposed and have bus electrode 12c and electrode refers to 13b, and make electrode refer to the plane graph of example of the IDT type auxiliary reflector electrode 3 ' of the mutual engagement of 13b.
The position everywhere that these IDT type auxiliary reflector electrodes 3 ' are configured is on the imaginary extended line of bus electrode 12a of IDT electrode 1.
Each IDT type auxiliary reflector electrode 3 ' all by with direction repeatedly (hereinafter referred to as " direction of IDT type auxiliary reflector electrode 3 ' ") G of each IDT type auxiliary reflector electrode 3 ' towards the IDT electrode and tilted configuration.
Also have, because do not connect holding wire on the IDT type auxiliary reflector electrode 3 ', so himself can not inspire elastic surface wave.
2 ladder mode filters that a plurality of elastic surface acoustic wave resonators of the usefulness that this is shown in Figure 11 are made are formed on the piezoelectric substrate 19, can constitute the elastic surface wave duplexer of acoustic surface wave element of the present invention.This structure as shown in figure 12, different just configuration ID T type auxiliary reflector electrodes 3 ' are used for replacing the auxiliary reflector electrode 3 among Fig. 1.
Also have, also can make the electrode of IDT type auxiliary reflector electrode 3 ' refer to that the spacing of bus electrode 14a of the spacing of 13b and reflector electrode 2 is different.Like this, just IDT type auxiliary reflector electrode 3 ' can be designed to reflector electrode 2 different wave lengths under improve its reflecting effect, even so there is the elastic surface wave of the wavelength that reflector electrode 2 can not reflect, also can carry out usable reflection, so can suppress the leakage in the outside of elastic surface wave direction elastic surface acoustic wave resonator more by IDT type auxiliary reflector electrode 3 '.
In addition, also can make the electrode of IDT type auxiliary reflector electrode 3 ' refer to that the spacing of 13b and the electrode of IDT electrode 1 refer to that the spacing of 13a is different, the unwanted resonance that takes place between control IDT type auxiliary reflector electrode 3 ' and the IDT electrode 1 becomes possibility like this, can obtain the few elastic surface acoustic wave resonator of clutter.
In addition, the situation of the duplexer of Figure 12, be used to launch the spacing that refers to 13b with the electrode of the IDT type auxiliary reflector electrode 3 ' of the acoustic surface wave element of filter if allow, refer to that with the electrode that is used to receive with the IDT electrode 1 of the elastic surface acoustic wave resonator of filter the spacing of 13a is identical, can improve the isolation performance in the frequency acceptance band.Its reason is, the elastic surface wave of the wavelength of the frequency acceptance band that the device electrode 2 of failing to be reflected reflects fully is by the 3 ' reflection of IDT type auxiliary reflector electrode and be enclosed in the acoustic surface wave element, and elastic surface wave becomes not to the reception filter leakage.
Continue it, can refer to that also 13b goes up a plurality of different spacings and mixes formation at the electrode of IDT type auxiliary reflector electrode 3 '.So, be not only specific frequency band, on wider frequency band, can suppress the elastic surface wave that leaks out from elastic surface acoustic wave resonator, thereby improve the Q value of elastic surface acoustic wave resonator, in this case, the spatial arrangements mode of a plurality of different spacing is particular importance not, can freely set.
Also have, the shape of IDT type auxiliary reflector electrode 3 ', can't help the electrode of rectilinear form refers to that the gate electrode that constitutes constitutes, but by the arc with certain curvature or curl or crooked shape, or is that the gate electrode that shape such as trapezoidal constitutes constitutes.So, the elastic surface wave that can leak in the reflection of angular range widely, thus can obtain to improve better the Q value of elastic surface acoustic wave resonator, improve the insertion of filter and lose, improve the effects such as isolation performance of duplexer.
Also have, in the IDT type auxiliary reflector electrode 3 ', the such simulation electrode 8 of IDT electrode shown in Figure 11 1 perhaps can be set, also or can electrode be referred to that the length of 13a and simulation electrode 8 carries out different settings, promptly carry out so-called change mark (Apodized) by the difference in place.So, both can reflect the elastic surface wave of wider scope wavelength that leaks out, can improve the reflection efficiency on some frequency again more, so can obtain better to improve the Q value of elasticity resonon, improve the insertion loss of filter, improve the effects such as isolation performance of duplexer.
In addition, also can between 2 IDT type auxiliary reflector electrodes 3 ' that closely connect, promptly dispose the second auxiliary reflector electrode 4 on two of reflector electrode 2 outsides.Figure 13 shows that the configuration illustration of the second auxiliary reflector electrode 4.
By this second auxiliary reflector electrode 4, can make to electrode to refer to the elastic surface wave reflection that reflector electrode 2 that the direction of 13a approximate vertical is propagated can not reflect fully with above-mentioned IDT electrode 1.
Also have, under the situation of the second auxiliary reflector electrode 4 as gate electrode 14b, also can make its spacing different with the spacing of the gate electrode 14a of reflector 2, also can only form IDT electrode (IDT type reflector) with gate electrode (open reflector), also can as illustrate, Fig. 5 make a plurality of different spacings mix the back and constitute.
Also have, the IDT type auxiliary reflector electrode 3 ' that adjoins each other is connected back formation one also can with the second auxiliary reflector electrode 4.
Example is provided with connecting portion 5a on the field after can prolonging in the bus electrode former state with the bus electrode of IDT type auxiliary reflector electrode 3 ' and the second auxiliary reflector electrode 4 and is connected as shown in Figure 14.
In addition, as shown in Figure 15, the electrode that also can arrive contact IDT type auxiliary reflector electrode 3 ' refers to till the 13b, and the field 5b that gate electrode 14b with the second auxiliary reflector electrode 4 has prolonged is set, and they are become one.At this moment, the bus electrode 25 that makes gate electrode 14B short circuit both can be set, also can not be provided with as shown in Figure 16.
Also have, as shown in figure 17, also can be formed on the IDT type auxiliary reflector electrode 3 ' of Figure 13 and the structure that the regional 5d place between the second auxiliary reflector electrode 4 is provided with gate electrode 14C.Also can form the structure that replaces gate electrode 14C with the IDT electrode.
Owing to form such structure, can reflect the elastic surface wave that leaks between the IDT type auxiliary reflector electrode 3 ' and the second auxiliary reflector electrode 4 more effectively, it is enclosed in the elastic surface acoustic wave resonator, can obtains the elastic surface acoustic wave resonator of higher Q.
In such structure, structure shown in Figure 15 and the structure of Figure 17 are because can obtain only gate electrode spacing, so favourable to all directions.
Also have, the shape of the second auxiliary reflector electrode be can't help the electrode of rectilinear form and is referred to that the gate electrode that constitutes constitutes, but by the arc with certain curvature or curl or crooked shape, or is that the gate electrode that shape such as trapezoidal constitutes constitutes.So, the elastic surface wave that can leak in the reflection of angular range widely, thus can reach the Q value that improves elastic surface acoustic wave resonator better, improve the insertion of filter and lose, improve the effects such as isolation performance of duplexer.
In addition, replace the reflector electrode 2 with Nogata body profile shape shown in Figure 11, the part that also can use the bus electrode 12b that makes reflector electrode 2 same as shown in Figure 10 tilts to IDT electrode 1, and makes the reflector electrode of shape of end flexing of the gate electrode 14a of reflector electrode.
Be illustrated above,, it can be applicable to communicator because elastic surface acoustic wave resonator of the present invention or acoustic surface wave element have the interior characteristic of good passband of the loss of inserting.
That is, in a side who has possessed launching circuit or receiving loop or both sides' communicator, can on band pass filter or duplexer, carry elastic surface acoustic wave resonator of the present invention or acoustic surface wave element.
Above-mentioned launching circuit is will transmit with frequency mixer to upload to carrier frequency, with the band pass filter unwanted signal of decaying, makes signal amplification with power amplifier then, by the loop of duplexer with the antenna emission.
Above-mentioned receiving loop is to receive received signal with antenna, and the received signal by duplexer is carried out amplification with low noise amplifier, then with the band pass filter unwanted signal of decaying, again with frequency mixer from carrier frequency with the Signal Separation and the loop of taking out.
The described communicator of having assembled duplexer and band pass filter, because of the insertion of its filter is lost low, can when obtaining identical power output, reduce required input power, thus the electric power that power amplifier consumes can be cut down, thus can obtain to suppress to consume the communicator of electric power.
In addition, owing to used and possessed emission filter region and the elastic surface wave duplexer that receives with filter on the piezoelectric substrate of the present invention, because the miniaturization of this elastic surface wave duplexer, the assembling area of other parts can be guaranteed, thereby small-sized, high performance communicator can be realized.Moreover because the isolated characteristic of its height can obtain high-quality speech quality.
Also have, actual execution mode of the present invention is not limited in above-mentioned example, only otherwise break away from purport of the present invention, can do various changes.
For example, as shown in figure 18, also can on the bus electrode 12b of bus electrode 12a and reflector electrode 2, thick film portion 6 be set further.So can suppress main combination of propagating the communication mode of circuit and bus electrode, leak the loss that causes thereby further suppress elastic surface wave.Moreover, shown in Figure 18 for be clipped in electrode refer to 13 and the gate electrode of reflector electrode 2 between, in the shape that thick film position 6 is set up and down symmetrically, but shape also can be different up and down.
Also have, the profile of IDT electrode not only can be Fig. 1, and rectangle shown in Figure 11 for example also can be become mark (Apodized) triangularity, diamond pattern, trapezoidal etc. shape.
Also have, the shape in the gate electrode field of reflector electrode also can be triangle, diamond pattern, shape such as trapezoidal.
Also have, position about the auxiliary reflector electrode, can be configured in and the IDT electrode of reflector electrode not on the imaginary line stretcher of the bus electrode of a side of adjacency, tilt angle theta surpasses 0 degree, below 20 degree, certain effect is arranged, but because existence exists with ... substrate orientation, IDT electrode thickness, electrode refers to the parameter of spacing of 13 etc., so resultful angle is not limited to this scope.
Also have, though the situation of ladder mode filter is illustrated, so long as the acoustic surface wave element of employing elastic surface waves such as DMS mode filter, transformer plain edition filter, IIDT mode filter all is applicable to the present invention.
＜embodiment 〉
At first, on a side's who propagates the piezoelectric substrate (substrate thickness 250 μ m) that the monocrystalline lithium tantalate substrates form by 38.7 ° of Y CUT X interarea, begin to make four layers of conductor counterdie that Ti/Al-1 quality %Cu/Ti/Al-1 quality %Cu forms successively from substrate one side with metallikon, thickness is respectively 6nm/104nm/6nm/104nm.
Then, this conductor counterdie is carried out pattern with photoetch and RIE (rie) to be formed, just be made into and had a plurality of elastic surface acoustic wave resonators that possessed IDT electrode (have various electrodes refer to bus electrode) and reflector electrode, auxiliary reflector electrode, and they are connected with ladder shape, the elastic surface wave duplexer that input and output electrode is arranged, as Fig. 2, shown in Figure 12.At this moment the etching gas of usefulness can be used the mist of BC13 and C12, and the spacing that wire spoke that electrode refers to and adjacent electrode refer to is all about 0.5 μ m.
In addition, as the example of comparing, made the elastic surface wave duplexer of structure shown in Figure 19 simultaneously with original structure.
Then, at input terminal 15,17 and lead-out terminal 16,18 and above the ring-shaped conductor 14, the stacked conductor layer of new Cr/Ni/Au is at each self-forming input and output pad on the input terminal 15,17 and on the lead-out terminal 16,18.
The thickness of the conductor layer that these are new is respectively 10nm/1000nm/100nm.So cutting substrate is divided into each chip.
Then, be contained in respectively on the real dress matrix of being made up of LTCC (Low Temperature Co-fired Ceramics) substrate the elastic surface wave duplexer of embodiments of the invention with as the duplexer of comparative example, the interarea that makes a side is relative and install.
At this, ltcc substrate has the pad electrode that the I/O attenuator of corresponding matrix side ring shape conductor of the ring-shaped conductor that forms on the side interarea with piezoelectric substrate 19 14 and elastic surface wave duplexer links to each other, and has printed scolder in advance on these matrix side ring shape conductors and pad electrode.
Secondly when the elastic surface wave duplexer carries out actual installation, consistent in order to make with these scolder patterns, configuration elastic surface wave duplexer applies ultrasonic wave and carries out virtual fixing, then by the heat fused scolder with ring-shaped conductor 14 and matrix side ring shape conductor, and I/O attenuator and pad electrode couple together.
So, each IDT electrode, reflector electrode and the I/O attenuator of elastic surface wave duplexer, fully sealed by the matrix side ring shape conductor of ltcc substrate and connected ring-shaped conductor 14.
In addition, the assembly work of above acoustic surface wave element will be carried out under nitrogen atmosphere.
Secondly; the opposite side interarea (back side) of acoustic surface wave element is protected with the model resin; at last; ltcc substrate is cut between each elastic surface wave duplexer, just obtained having the acoustic surface wave element of the elastic surface wave duplexer of elastic surface wave duplexer in the embodiments of the invention and comparative example.
(1) have the situation of auxiliary reflector electrode 3 (Fig. 2):
Figure 20 shows that the chart of isolated characteristic of the duplexer of the structure among Fig. 2.
On the chart of Figure 20, transverse axis is represented normalized frequency, and the longitudinal axis is represented isolated characteristic (unit: dB).The characteristic curve of dotted line is represented original not with the result of auxiliary reflector electrode 3, shown in Figure 19 elastic surface wave duplexer; The characteristic curve of solid line is illustrated in the result who has added the embodiments of the invention of auxiliary reflector electrode 3 on the original elastic surface wave duplexer.
From result shown in Figure 20 as can be known, even if elastic surface wave duplexer of the present invention is that its isolation performance is compared with comparative example has big improvement under 0.95 the situation in the normalization frequency, maximum differential reaches 5dB.
Can think the duplexer of formation of comparative example, leak the leakage elastic surface wave of propagating because exist with the elastic surface acoustic wave resonator of filter, so can not obtain good characteristic from constituting emission.
The illustration that Figure 21 compares the impedance operator (dotted line) of the impedance operator (solid line) of elastic surface acoustic wave resonator and original elastic surface acoustic wave resonator for 1 terminal that will make of elastic surface acoustic wave resonator of the present invention.
In Figure 21, transverse axis represents that the longitudinal axis is represented the absolute value of impedance with the frequency after the optional frequency normalization | Z| (Ω of unit).Impedance | the peak value of Z| partly is called as the antiresonance impedance.
In the present invention shown in Figure 21, the peak value that is called as antiresonance resistance 11 can be increased, improve Q.Constitute under the situation of ladder shape structure,, can make big more can the minimizing more of antiresonance resistance 11 of the elastic surface acoustic wave resonator arranged side by side of ladder-type filter insert loss with the parameter that can have influence on the insertion loss in the passband.Specifically, to be about 900 Ω corresponding with antiresonance resistance 11 of the present invention, originally be not about 840 Ω with the antiresonance resistance 10 of auxiliary reflector electrode 3, obtain the significantly improvement of about 60 Ω by the present invention.
In addition, Figure 22 is to be transverse axis with the angle theta that forms between between the main direction of propagation F of the elastic surface wave of the G of direction repeatedly of the gate electrode 14B of auxiliary reflector electrode 3 and IDT electrode 1 (unit: °), and the antiresonance resistance is a longitudinal axis (unit: schematic diagram Ω).
Test is learnt thus, changes to 20 °, about 62 Ω that improve of antiresonance resistance by making the θ angle from 0 °.
Also have, the angle theta between the elastic surface wave master direction of propagation F of the direction G of auxiliary reflector electrode 3 and IDT electrode 1 according to desirable characteristic, also can be made as more than 20 °.
In addition, Figure 23 is the enlarged drawing of emission with the passband internal characteristic of filter.Transverse axis represents that the longitudinal axis is represented attenuation (unit: dB) with the normalized frequency of optional frequency in Figure 23.
Get the angle θ that forms between the elastic surface wave master direction of propagation F of the direction G of auxiliary reflector electrode 3 and IDT electrode 1 (unit: °) and be parameter, dotted line is 5 °, and the some broken line is 10 °, and dotted line is 15 °, and solid line is 20 °.In Figure 23, improvement the best of the insertion loss when the θ angle is 20 ° is compared the improvement that about 0.1dB is arranged with 5 ° situation.
Also have, with with the complete same method of top embodiment explanation, allow the spacing of gate electrode 14b of auxiliary reflector electrode 3 refer to that with the electrode of IDT electrode 1 13 spacing is different, make duplexer, carried out above-mentioned evaluation with elastic surface acoustic wave resonator of the present invention.
Its result represents with Figure 24.Shown in Figure 24 is that top sketch map is identical with Fig. 2, but the spacing of the gate electrode 14b of auxiliary reflector electrode 3 and the electrode of IDT electrode 1 refer to the isolated characteristic under the different condition of 13 spacing.
In the chart of Figure 24, transverse axis is represented normalized frequency, and the longitudinal axis is represented isolated characteristic (unit: dB).The characteristic curve of dotted line is represented original not with the result of the comparative example of auxiliary reflector electrode 3, dotted line and solid line represent to have the example of the present invention of auxiliary reflector electrode 3 respectively, and dotted line represents that the electrode spacing of relative gate electrode 14B with original elastic surface acoustic wave resonator and the electrode of IDT electrode 1 refer to 13 the identical situation of spacing; Solid line represents that the electrode spacing of gate electrode 14B is 2 times the situation that the electrode of IDT electrode 1 refers to 13 spacing.
The result who represents from Figure 24 can find out obviously that the elastic surface acoustic wave resonator of present embodiment is compared with comparative example, and isolated characteristic has had the maximum improvement that reaches 6dB.
(2) have the situation of IDT type auxiliary reflector electrode 3 ' (Figure 12):
About embodiments of the invention and the comparative example made, its isolated characteristic as shown in figure 25.
In the chart of Figure 25, transverse axis is represented normalized frequency, and the longitudinal axis is represented isolated characteristic (unit: dB).The characteristic curve of dotted line is represented originally not the result with the comparative example shown in Figure 19 of IDT type auxiliary reflector electrode 3 ', and the characteristic curve of solid line represents to have the result of the embodiments of the invention of IDT type auxiliary reflector electrode 3 '.
As can be seen from Figure 25, the elastic surface wave duplexer of this embodiment is compared isolated characteristic with the situation of comparative example and is made moderate progress, and the improvement of 9dB is for example arranged when normalization frequency 1.005 approximately.Can think the duplexer of comparative example, because exist from constituting the surface wave that emission leaks out with the elastic surface acoustic wave resonator of filter, so can not obtain good characteristic.
In addition, the impedance operator (solid line) of elastic surface acoustic wave resonator is compared with the impedance operator (dotted line) of original elastic surface acoustic wave resonator, obtain chart shown in Figure 26 with 1 terminal of elastic surface acoustic wave resonator making of the present invention.Shown in solid line, can confirm to improve the peak value that is called as antiresonance resistance 11.Specifically, to be about 819 Ω relative with antiresonance resistance 11 of the present invention, originally be not 812 Ω with the antiresonance resistance 10 of the elastic surface acoustic wave resonator of IDT type auxiliary reflector electrode 3 ', can obtain the improvement of about 7 Ω by the present invention.
In addition, Figure 27 for the angle theta that forms between the main direction of propagation F with the elastic surface wave of auxiliary reflector electrode 3 ' direction G and IDT electrode 1 (unit: °) during as transverse axis with the antiresonance resistance as the longitudinal axis (unit: schematic diagram Ω).
Experiment changes to 10 ° by making the θ angle from 0 ° as can be known thus, and the antiresonance resistance approximately can improve 14 Ω.And when being made as 10 ° of left and right sides, the θ angle can obtain best improvement.
From the antiresonance resistance being made as best angle, preferably the angle theta that forms between the main direction of propagation F with the elastic surface wave of the direction G of IDT type auxiliary reflector electrode and IDT electrode 1 is located at 5 ° to 10 ° scope.
In addition, if this angle during greater than 10 °, the antiresonance resistance diminishes.But as Figure 29 explanation described later, its isolated characteristic is not subjected to angle restriction and improves.
In addition, Figure 28 is that the emission of duplexer shown in Figure 12 is with the enlarged drawing of filter at the passband internal characteristic.
In Figure 28, transverse axis represents that the longitudinal axis is represented attenuation (dB of unit) with the normalized frequency of optional frequency.
Get angle θ (unit: °) and be parameter, the chart when dotted line is represented angle 9=0 °, phase therewith, solid line represents that angle θ is 10 ° a situation.In Figure 28, as can be known, under the condition of θ=10 °, insert loss and improved about 0.1dB with existing comparing.
In addition, about the position of IDT type auxiliary reflector electrode, being configured in will be positioned on the IDT electrode of the reflector electrode straight line after the bus electrode imagination of a side of adjacency prolongs, the influence to isolated characteristic during tiltangle for a change shown in Figure 29.
Get angle θ (unit: °) as parameter, transverse axis represents that with the normalized frequency of optional frequency, the longitudinal axis is represented isolated characteristic (dB of unit).
Along with the tilt angle theta of IDT type auxiliary reflector electrode increases 0 °～20 ° scopes, the isolated characteristic in the wide frequency ranges is also improved thereupon, is that 0 ° situation is compared with θ when θ is 20 °, and maximum has the improvement of about 2dB.
In addition, use the identical method with top embodiment explanation, the spacing that the electrode of making IDT type auxiliary reflector electrode 3 ' refers to 13b and the electrode of IDT electrode 1 refer to the different elastic surface wave duplexer of spacing of 13a, have carried out above-mentioned evaluation.
The result as shown in figure 30, make under 2 times the situation of spacing that the electrode of IDT electrode 1 refers to 13a the electrode of IDT type auxiliary reflector electrode 3 ' being referred to the spacing of 13b, at the 1.00 frequency places that are equivalent to launch with in the passband of filter, compare the improvement that isolated characteristic has about 9dB with original duplexer.
Figure 31 is the chart that the connection ID T type auxiliary reflector electrode 3 ' shown in Figure 14 and the second auxiliary reflector electrode 4 form isolated characteristic under the situation of one, duplexer.Dotted line is represented is the structure shown in Figure 13 situation that to be IDT type auxiliary reflector electrode 3 ' be not connected with the second auxiliary reflector electrode 4, and what solid line was represented is that structure shown in Figure 14 is the situation that the IDT type auxiliary reflector electrode 3 ' and the second auxiliary reflector electrode 4 link together.As can be seen, in solid line, and be not connected to such an extent that situation is compared, the normalization frequency in 0.98～1.02 scope widely, the improvement of nearly 1dB.
Claims (17)
1. elastic surface acoustic wave resonator wherein, has:
Piezoelectric substrate;
The IDT electrode, it is formed on the described piezoelectric substrate, has the bus electrode that extends abreast with the main direction of propagation of the elastic surface wave of propagating on described piezoelectric substrate;
Reflector electrode, it is formed on the described piezoelectric substrate, with the two ends of the main conduction orientation of the elastic surface wave of described IDT electrode in abutting connection with and dispose;
The auxiliary reflector electrode, it is formed on the described piezoelectric substrate, has the electrode that is concatenated to form, the position in the outside of described reflector electrode, the hypothesis that is configured in the bus electrode of described IDT electrode prolongs on the straight line, and
Described auxiliary reflector electrode is positioned at than the farther position of the described reflector electrode described IDT electrode of distance.
2. elastic surface acoustic wave resonator according to claim 1 is characterized in that, described auxiliary reflector electrode forms the direction repeatedly of the described electrode that is concatenated to form, towards described IDT electrode.
3. elastic surface acoustic wave resonator according to claim 1, it is characterized in that, the direction repeatedly of the described electrode that is concatenated to form of described auxiliary reflector electrode, the angle θ that the direction repeatedly that refers to the electrode of described IDT electrode forms surpasses 0 degree, is lower than 20 degree.
4. elastic surface acoustic wave resonator according to claim 1 is characterized in that, described auxiliary reflector electrode is configured on four positions in the oblique outside of described reflector electrode.
5. elastic surface acoustic wave resonator according to claim 1 is characterized in that, the both ends short circuit of the described electrode that is concatenated to form of described auxiliary reflector electrode.
6. elastic surface acoustic wave resonator according to claim 1 is characterized in that, an end of the described electrode that is concatenated to form of described auxiliary reflector electrode has on electrical characteristics by open shape.
7. elastic surface acoustic wave resonator according to claim 1 is characterized in that, the both ends of the described electrode that is concatenated to form of described auxiliary reflector electrode have on electrical characteristics by open shape.
8. elastic surface acoustic wave resonator according to claim 1, it is characterized in that, described auxiliary reflector electrode has 2 bus electrodes, and described auxiliary reflector electrode has and makes that upwardly extending electrode refers to the shape that meshes in approximate right angle side from described bus electrode.
9. elastic surface acoustic wave resonator according to claim 1 is characterized in that, the spacing of the described electrode that is concatenated to form of described auxiliary reflector electrode is different with the spacing of described reflector electrode.
10. elastic surface acoustic wave resonator according to claim 1 is characterized in that, the spacing of the described electrode that is concatenated to form of described auxiliary reflector electrode is different with the spacing of described IDT electrode.
11. elastic surface acoustic wave resonator according to claim 4 is characterized in that, between locational 2 auxiliary reflector electrodes in the outside that is formed at described reflector electrode, is formed with the second auxiliary reflector electrode.
12. elastic surface acoustic wave resonator according to claim 11 is characterized in that, the described second auxiliary reflector electrode formation one that is connected with described auxiliary reflector electrode.
13. an acoustic surface wave filter is characterized in that, on piezoelectric substrate, the described elastic surface acoustic wave resonator of a plurality of claims 1 is set and forms.
14. a surface elasticity wave duplexer is characterized in that, on piezoelectric substrate, possesses emission filter field and reception filter field,
The described elastic surface acoustic wave resonator of claim 1 is located at described emission to be used at least one side of filter field with filter field or reception.
15. a communicator is characterized in that, is equipped with the described elastic surface acoustic wave resonator of claim 1.
16. a communicator is characterized in that, is equipped with the described acoustic surface wave filter of claim 13.
17. a communicator is characterized in that, is equipped with the described surface elasticity wave duplexer of claim 14.
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| JP4694609B2 (en) * | 2008-10-24 | 2011-06-08 | 日本電波工業株式会社 | Elastic wave filter |
| JP5875857B2 (en) * | 2011-12-26 | 2016-03-02 | オリンパス株式会社 | Ultrasonic vibration device and ultrasonic medical device |
| WO2015064238A1 (en) * | 2013-10-31 | 2015-05-07 | 京セラ株式会社 | Elastic wave element, filter element and communication device |
| WO2016147688A1 (en) * | 2015-03-16 | 2016-09-22 | 株式会社村田製作所 | Elastic wave device and production method for same |
| CN116938188B (en) * | 2023-09-15 | 2024-01-09 | 广州市艾佛光通科技有限公司 | Surface acoustic wave resonator device, surface acoustic wave filter device and electronic equipment |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5365138A (en) * | 1993-12-02 | 1994-11-15 | Northern Telecom Limited | Double mode surface wave resonators |
| US6297712B1 (en) * | 1998-05-21 | 2001-10-02 | Murata Manufacturing Co., Ltd. | Multi-mode edge reflection saw filter device with ground electrodes between stages, duplexer, and communication device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5365138A (en) * | 1993-12-02 | 1994-11-15 | Northern Telecom Limited | Double mode surface wave resonators |
| US6297712B1 (en) * | 1998-05-21 | 2001-10-02 | Murata Manufacturing Co., Ltd. | Multi-mode edge reflection saw filter device with ground electrodes between stages, duplexer, and communication device |
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