CN1725638A - Multichannel decomposer - Google Patents
Multichannel decomposer Download PDFInfo
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- CN1725638A CN1725638A CN 200410071336 CN200410071336A CN1725638A CN 1725638 A CN1725638 A CN 1725638A CN 200410071336 CN200410071336 CN 200410071336 CN 200410071336 A CN200410071336 A CN 200410071336A CN 1725638 A CN1725638 A CN 1725638A
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Abstract
A multi-path splitter consists of a common terminal, multiple surface sonic- filters with signal terminal being connected to common terminal and with different pass-band , a phase shifter being set between common terminal and one of said filters and being able to use its input impedance to influence matching between common terminal impedance and signal terminal impedance in pass-band of said filter .
Description
Technical field
The present invention relates to a kind of demultiplexer that utilizes a plurality of surface acoustic wave filters, wherein said surface acoustic wave filter is made of a plurality of surface acoustic wave elements that form on the Piezoelectric Substrates.
Background technology
The surface acoustic wave filter that is made of a plurality of surface acoustic wave elements that form on the Piezoelectric Substrates is known as the high freguency bandpass filter that is used for mobile communication application etc.
As such surface acoustic wave filter, a kind of known surface acoustic wave filter is arranged, it constitutes a kind of ladder circuit, and this circuit has in a series arm that forms between input terminal and the lead-out terminal, a plurality of parallel branches that form between this series arm and reference potential terminal and the SAW (Surface Acoustic Wave) resonator that suitably places described series arm and parallel branch.Also have a kind of known technology, be used for forming a demultiplexer by the logical different a plurality of such step surface acoustic wave filter of frequency of band.
For example, at Japan Patent No.3, a kind of technology of describing in 246,906 is known as background technology.
Figure 23 is the equivalent circuit diagram of a kind of background technology demultiplexer of expression.Figure 24 illustrates near the frequency characteristic of demultiplexer shown in Figure 23 passband.Figure 25 illustrates the frequency characteristic of demultiplexer shown in Figure 23 in the harmonic wave zone.
As shown in figure 23, at Japan Patent No.3,246, a kind of technology is disclosed in 906, wherein, the public terminal C side initial level of first surface acoustic wave filter BF1 is provided as the T input, and the public terminal C side initial level of second surface acoustic wave filter BF2 is provided as the π input, thereby has quoted delay line 9 between described public terminal C and second surface acoustic wave filter BF2.Incidentally,, also disclose a kind of technology in 246,906, replaced delay line 9 with an inductive element at Japan Patent No.3.
According to this technology, allegedly can easily constitute a demultiplexer, and can too much not damage the primary characteristic of filter shown in Figure 24.
[patent documentation 1]
Japan Patent No.3,246,906
In recent years, require more and more to reduce the size and the thickness of demultiplexer, and improve the characteristic in the harmonic wave zone.
Especially, because the restriction of surface acoustic wave element size and structure uses the frequency band that is not higher than 1GHz to be difficult to reduce the size of demultiplexer.
When using delay line, can obtain wavelength decreases effect based on the dielectric constant of used dielectric substrate.For example, in the system that uses the 300MHz frequency band, when using dielectric constant to be approximately 4 expoxy glass plate, delay line needs about 40mm long, and when using dielectric constant to be approximately 7 ceramic wafer, delay line needs about 35mm long.Correspondingly, consider between the delay line crosstalk and phase place reduces, be difficult in less than the space content of 5mm * 5mm and receive delay line.
Therefore, when using above-mentioned delay line to constitute demultiplexer, can't satisfy the requirement that reduces size and thickness, determine because the shape of demultiplexer is a physical dimension according to delay line.
In recent years, along with the directly progress of conversion in the RF circuit part of mobile communication terminal, require secondary, three times and the four-time harmonic of decay receiving filter more and more.But the phase shifter of the delay line of use distributed constant circuit form can not effectively help improve the decay in the harmonic wave zone, because delay line is a distributing line, thereby the filter effect of delay line is very poor.
Summary of the invention
Therefore, an object of the present invention is to provide a kind of demultiplexer, wherein can realize reducing size, and in other frequency band except that passband, realize big decay.
In order to address this problem, according to the present invention, provide a kind of demultiplexer, comprising: public terminal; A plurality of surface acoustic wave filters are made of surface acoustic wave device, have the signal terminal that is connected to described public terminal, and have different passband mutually; And the phase shifter that constitutes by the lumped constant element that places between described public terminal and the predetermined surface acoustic wave filter, its input impedance influence from the public terminal side see the impedance in the passband of predetermined surface acoustic wave filter and the impedance seen from the signal terminal side between coupling.
According to reduce when using delay line between the contingent delay line near crosstalking of causing and phase place shortens, the present invention helps reducing the size of the phase shifter that is made of lumped constant element itself and helps improving the interelement design characteristics and reduce size.Correspondingly, compare, can realize that bigger size reduces with the demultiplexer that uses delay line.
In addition, provide the phase shifter that constitutes by lumped constant element, make that the interior signal component of other frequency band except that passband is decayed by phase shifter.Correspondingly, in other frequency band except that passband, can realize big decay.Correspondingly, can significantly improve the performance of demultiplexer.
Description of drawings
Fig. 1 illustrates the equivalent circuit diagram of demultiplexer according to an embodiment of the invention;
Fig. 2 illustrates the characteristic curve of the filter that is used for demultiplexer shown in Figure 1;
Fig. 3 illustrates the input impedance characteristic of filter in the broadband;
Fig. 4 illustrates the input impedance characteristic of vertical double mode surface acoustic wave filter;
Fig. 5 illustrates the broken away view of the concrete structure of demultiplexer shown in Figure 1;
Fig. 6 illustrates the example of a kind of variation of above-mentioned demultiplexer concrete structure;
Fig. 7 illustrates the example of a kind of variation of capacitive element in the above-mentioned demultiplexer concrete structure;
Fig. 8 illustrates with using delay line and compares, and uses the transmission characteristic of the phase shifter of lumped constant element;
Fig. 9 illustrates with using delay line and compares, and uses the phase characteristic of the phase shifter of lumped constant element;
Figure 10 compares with using delay line for expression, the Smith chart of the impedance operator of the phase shifter of use lumped constant element;
Figure 11 illustrates near the frequency characteristic of demultiplexer shown in Figure 1 passband;
Figure 12 illustrates the frequency characteristic of demultiplexer shown in Figure 1 in the harmonic wave district;
Figure 13 is the Smith chart of the impedance variation of second surface acoustic wave filter in the expression demultiplexer shown in Figure 1;
Figure 14 is the equivalent circuit diagram of demultiplexer according to another embodiment of the present invention;
Figure 15 is near the frequency characteristic of demultiplexer shown in Figure 14 passband;
Figure 16 is the frequency characteristic of demultiplexer shown in Figure 14 in the harmonic wave district;
Figure 17 is the equivalent circuit diagram of demultiplexer according to another embodiment of the present invention;
Figure 18 is the equivalent circuit diagram of demultiplexer according to another embodiment of the present invention;
Figure 19 is near the frequency characteristic of demultiplexer shown in Figure 17 passband;
Figure 20 is the frequency characteristic of demultiplexer shown in Figure 17 in the harmonic wave district;
Figure 21 is near the frequency characteristic of demultiplexer shown in Figure 180 passband;
Figure 22 is the frequency characteristic of demultiplexer shown in Figure 180 in the harmonic wave district;
Figure 23 illustrates the equivalent electric circuit of prior art demultiplexer;
Figure 24 is near the frequency characteristic of demultiplexer shown in Figure 23 passband;
Figure 25 is the frequency characteristic of demultiplexer shown in Figure 24 in the harmonic wave district;
Embodiment
Specifically describe one embodiment of the present of invention below with reference to the accompanying drawings.In the accompanying drawings, represent identical parts, to avoid repeat specification with identical label.Although this embodiment of the present invention helps to realize the present invention especially, the invention is not restricted to this embodiment.
Demultiplexer according to this embodiment provides like this, makes predetermined element at for example LiTaO
3Form on the Piezoelectric Substrates.That is, in Fig. 1, demultiplexer has public terminal C, transmitting filter (first surface acoustic wave filter) BF1 and receiving filter (second surface acoustic wave filter) BF2.The signal I/O is undertaken by public terminal C.Transmitting filter BF1 has a signal terminal t1, is connected to public terminal C by contact J, and another signal terminal t2 is connected to first signal terminal 1.Receiving filter BF2 has a signal terminal t3 to be connected to public terminal C by contact J, and another signal terminal t4 is connected to secondary signal terminal 2.
Transmitting filter BF1 and receiving filter BF2 have such frequency characteristic, make the passband of a filter as the stopband of another filter.That is, transmitting filter BF1 has different mutually passbands and mutual different frequency characteristic with receiving filter BF2.In this embodiment, the passband of receiving filter BF2 is set to be higher than the passband of transmitting filter BF1.
Although this embodiment illustrates the situation that the passband of receiving filter BF2 is higher than the passband of transmitting filter BF1, the passband of filter BF1 and BF2 also can be provided with on the contrary.Piezoelectric Substrates is not limited to above-mentioned example.For example, any suitable Piezoelectric Substrates is as LiNbO
3Piezoelectric Substrates or ceramic substrate all can be used.
By lumped constant element being used to of constituting the decay phase shifter 6 of the signal component in the frequency band beyond the passband of receiving filter BF2 place between public terminal C and the receiving filter BF2.
Fig. 2 illustrates the impedance operator of seeing transmitting filter BF1 from public terminal C side.The impedance of for example about 50 Ω of the impedance ratio of transmitting filter BF1 in the passband of receiving filter BF2 is enough high, and 50 Ω are the passband input impedance of second surface acoustic wave filter BF2, also is the impedance of seeing from signal terminal t1.Even when two filter BF1 and BF2 are connected to public terminal C as shown in the figure, transmitting filter BF1 can not influence second surface acoustic wave filter BF2 yet, and second surface acoustic wave filter BF2 mates the impedance of entire circuit in the passband of this second surface acoustic wave filter BF2.That is to say, realized the function that multichannel is decomposed.
Fig. 2 also illustrates the impedance operator of seeing receiving filter BF2 from public terminal C side.The impedance of receiving filter BF2 in the passband of transmitting filter BF1 shows as the little value of about 15 Ω.When two filter BF1 and BF2 were connected to public terminal as shown in the figure, the impedance meeting of receiving filter BF2 in the passband of first surface acoustic wave filter BF1 influenced the impedance operator of transmitting filter BF1.That is, upset the multichannel decomposition function.Therefore must provide certain impedance conversion device.
As mentioned above, be connected at a plurality of filters under the situation of public terminal C, the multichannel decomposition function is to determine according to the input impedance of seeing each filter from public terminal C side.That is, the multichannel decomposition function is not limited only to Filter Structures.Fig. 3 illustrates the side from public terminal C, the broadband impedance characteristic of transmitting filter BF1 and receiving filter BF2.In Fig. 3, if the passband of transmitting filter BF1 is positioned at the low-frequency band side, then needn't provide any phase shifter, because input impedance increases along lower frequency side.
Same principle also is applicable to the situation of using vertical coupled surface acoustic wave filter.Fig. 4 illustrates the impedance operator of seeing vertical coupled surface acoustic wave filter from the public terminal side.Equally in this case, the impedance operator of a filter is connected to the passband determining positions of other filter of public terminal according to the above identical mode basis to the influence of the impedance in another filter passband.Whether present the multichannel decomposition function, and provide the necessity of phase shifter to determine.Obviously, same principle also can be applicable to other Mode Coupling type surface acoustic wave filter, cross section type surface acoustic wave filter, notch filter etc.
Describe below with reference to Fig. 5 and a kind ofly can multichannel to decompose the transmitting filter that is connected to public terminal C and receiving filter and do not need to use the minitype high-performance demultiplexer of any delay line.
For example, as shown in Figure 5, form by the plate of four-layer structure according to the demultiplexer of this embodiment.Each plate is together with each other and is in alignment with each other.Transmitting filter BF1, receiving filter BF2, first signal terminal 1, secondary signal terminal 2 and reference potential terminal C form on the plate 11 that is positioned at the superiors.
Incidentally, one is fixed on flip chip mode filter on the plate 11 by flip-chip method, or the circuit fixed filter that is fixed on the plate 11 by sealing wire can be used as each transmitting filter BF1 and receiving filter BF2.But, preferably use the flip chip mode filter from high-density installation and the viewpoint that changes by the frequency characteristic that the perception of sealing wire causes.
Forming phase shifter 6, the three ply boards 13 and the 4th laminate 14 that are made of the lumped constant element that constitutes by π type low pass filter (LPF) on second laminate 12 is orlop.That is, the inductive element 7 that is made of the bending wire pattern forms on plate 12.The relative terminal of inductive element 7 is connected electrically to public terminal C and the receiving filter BF2 on the plate 11 respectively.On plate 13, form two electrode pattern 8a of the capacitive element 8 of the relative terminal that is connected respectively to inductive element 7.On plate 14, form by the counterelectrode pattern 8b that predetermined gap is relative with electrode pattern 8a.
Incidentally, the pattern of perception and capacitive element 7 and 8 is not limited to example shown in Figure 5.For example, the shape of inductive element 7 can be a spirality shown in Figure 6, and the shape of capacitive element 8 can be a fusiformis shown in Figure 7.
Demultiplexer can form three-dimensional multilayer structure unlike diagram, but forms two-dimensionally in a plane.
In the following description, the demultiplexer according to this embodiment forms the feasible phase shifter 6 of lumped constant element that uses as an encapsulation that comprises transmitting filter BF1 and receiving filter BF2.Alternatively, phase shifter 6 can be used as the so-called external type unit that separates with receiving filter BF2 with transmitting filter BF1.
When representing with circuit, using the phase shifter 6 of lumped constant element is the π type low pass filter that is expressed as π type equivalent electric circuit.That is, comprise inductive element 7, be arranged in transmission line and two capacitive elements 8 of extending from public terminal C, lay respectively between two the relative terminals and reference potential terminal C of inductive element 7 as the low pass filter of the phase shifter 6 that uses lumped constant element.In the following description, use the phase shifter 6 of lumped constant element to comprise three elements.Alternatively, phase shifter 6 can comprise the element of desired number, as 5 or 7.
Compare with the delay line that uses distributed constant, the size of lumped constant element can significantly be dwindled.Traditionally, use the demultiplexer of surface acoustic wave device usually to constitute by delay line as the distributed constant element.
The characteristic impedance of delay line is designed to about 50 Ω, and this is the input impedance of the surface acoustic wave device that connects or the driving impedance or the load impedance of this device.Correspondingly, the live width of delay line need be arranged in the scope of 40-120 μ m for example.In addition, delay line designs on mounting panel, makes to obtain desired phase, and a gap is provided between delay line simultaneously, in order to avoid cause characteristic impedance to reduce by the coupling between the delay line.Therefore, need big erection space inevitably.
In the prior art, the demultiplexer of use delay line is used for the frequency band range of 800MHz-2GHz, thereby erection space remains on about 5mm * 5mm.From further reducing the viewpoint of size, can not satisfy the requirement that fully reduces size when using delay line.
On the other hand, phase shifter provides usually under the following conditions, and promptly delay line is difficult in lower band, as using in HF frequency band or the VHF frequency band.This is because actual formation is very difficult greater than the line length of 1m on circuit board.The use of delay line is limited under the situation that allows spatial limitation.In most of the cases, in these frequency bands, use the phase shifter of lumped constant element.
Therefore, the inventor considers and can solve the problem that the demultiplexer size reduces with same principle.Use lumped constant element although have no precedent the example of a phase shifter structure in the microwave region, size equal 100,000 of electromagnetic wavelength/ surface acoustic wave device in the phase shifter that uses correspondingly need quite little size.
But in the technology of using traditional delay line, be difficult to reduce again the size of delay line.Therefore, use lumped constant element further to reduce size in the phase shifter structure in the demultiplexer that uses surface acoustic wave device.
Along with every line width diminishes, can obtain bigger inductance as the perceptual device of lumped constant element.Along with the gap turn narrow between line, because the inductance of induction in the gap itself makes total inductance increase.Therefore, use inductance than using live width to be subjected to the delay line of characteristic impedance restriction more to help reducing size.On the other hand, capacitor also helps reducing size, because electric capacity reduces along with the gap between two relative conductors of capacitor and increases.By using the stacked structure of multi-layer sheet, be easy to obtain capacitor.Therefore, the inventor considers to use the phase shifter of lumped constant element to help reducing size, even consider to increase under the situation of parts number too.
Incidentally,, described a kind of technology in 246,906 the claim 4, made a delay line from inductance L as lumped constant element at Japan Patent No.3.It is not enough only using inductance.In any inductance range, the impedance operator of the filter of connection all is shifted by perception in all frequency bands that comprise passband and other frequency band except that passband.Therefore, in the filter that fully mates, any part of matching characteristic all obviously worsens.Therefore, as Japan Patent No.3,246,906 described like that only to constitute demultiplexer from the circuit that uses series inductance be worthless.A match reactance element preferably is provided again.
In the present invention, consider that this on the one hand, phase shifter constitutes like this, makes that the impedance of phase shifter can fully be mated with load/driving impedance in desired frequency (for example can use series inductance and shunt capacitance), and can realize the necessary phase place anglec of rotation at this expected frequency.In addition, phase shifter is provided with like this, makes in the compression frequency band except that passband, can obtain the attenuation characteristic of expecting simultaneously by π or T impedance elements filters.
The configuration of the phase shifter 6 that is inserted into provides according to I/O impedance Z lump, phase place anglec of rotation γ and the parts number of phase shifter at expected frequency.Use the easy configuration of three elements to provide by following formula:
Zlump＝(L/C)1/2
γ＝jω(L/C)1/2
Wherein, ω is the expectation angular frequency.
Phase shifter as using lumped constant element can provide four kinds of filters, that is: T low pass filter shown in Figure 14, π low pass filter shown in Figure 1, π high pass filter shown in Figure 17 and T high pass filter shown in Figure 180.Figure 14,17 and 18 content hereinafter will be described.
All component values of four kinds of filters are provided by above expression formula.Impedance and the phase place anglec of rotation of these four kinds of filters in desired frequency band equates, but the transmission characteristic difference in other frequency band.Value at given γ is under the condition of half, if element is cascaded connection, so that concentrate the components identical part after calculating, then parts number can become 5 from 3.
Fig. 8 illustrates to have according to the pass-band performance of the phase shifter of four kinds of structures of the present invention and the comparison of pass-band performance in the 2GHz frequency band of prior art equipment.Clearly, decay seldom shows signal attenuation and have in the higher and lower band of phase shifter beyond desired frequency band according to four kinds of structures of low pass filter of the present invention and high pass filter in the scope of the pass-band performance of prior art below 10GHz.
Fig. 9 illustrates to have according to the phase characteristic of the phase shifter of four kinds of structures of the present invention and the comparison of phase characteristic in the 2GHz frequency band of prior art equipment.Clearly, each low pass filter provides the phase place identical with using delay line at expected frequency, and each high pass filter provides the phase place identical with using delay line in the frequency that is different from expected frequency.According to the setting of L and C, can provide arbitrarily and the I/O impedance of each device and the consistent Zlump and the γ of load/driving impedance of device.
Figure 10 illustrates the Smith's figure line according to the impedance operator of four kinds of phase shifters of the present invention.In the prior art, delay line shows the transmission characteristic of mating with load/driving impedance in broadband.On the other hand, has mutual distinct reflection coefficient in phase shifter according to the present invention other frequency band outside desired frequency band.
As mentioned above, compare with the situation of using delay line, phase shifter according to the present invention is characterised in that, multiple transmission characteristic, multiple phase characteristic and multiple impedance operator can be provided in other frequency band outside desired frequency band.Therefore, although can satisfy the impedance operator and the phase characteristic of phase shifter in desired frequency band, in other frequency band outside desired frequency band, transmission characteristic can change.
Figure 11 illustrates demultiplexer with said structure in the contiguous frequency characteristic of passband.Figure 12 illustrates the frequency characteristic of demultiplexer in the harmonic wave zone.Figure 13 is illustrated in Smith's figure line of the impedance operator of the receiving filter BF2 that the receiver side of demultiplexer provides.
As shown in figure 11, transmitting filter BF1 is different mutually with the passband of receiving filter BF2, and the passband of receiving filter BF2 is higher than the passband of transmitting filter BF1.As shown in figure 12, compare with the situation of using delay line, the signal component of receiving filter BF2 in the harmonic wave zone significantly reduces (BF1 ' and BF2 '), because phase shifter 6 useful effects of use lumped constant element are in signal component.As shown in figure 13, obviously the impedance of receiving filter turns clockwise providing and the characteristic of using delay line to equate, but has inserted lumped constant element, and has obtained the harmonic wave suppression characteristic.As shown in figure 11, obviously in the passband of BF1, provide transmission characteristic, make the transmission characteristic in its passband that is equivalent to BF2.
When using demultiplexer, can improve the attenuation characteristic in the harmonic wave zone of receiving filter, the feasible size that might further reduce demultiplexer.
For example, the T low pass filter of representing with T shape equivalent electric circuit among Figure 14 can be as the phase shifter 6 that uses lumped constant element.That is to say, low pass filter, phase shifter 6 promptly shown in Figure 14 comprises two inductive elements 7, is arranged in transmission line and a capacitive element 8 of extending from public terminal C, between the mid point and reference potential terminal G of inductive element 7.
Figure 15 illustrates phase shifter 6 shown in Figure 14 in the contiguous frequency characteristic of passband.Figure 16 illustrates the frequency characteristic of phase shifter 6 in the harmonic wave zone.As shown in figure 15, transmitting filter BF1 and receiving filter BF2 have passband separately, and wherein the passband of receiving filter BF2 is higher than the passband of transmitting filter BF1.As shown in figure 16, compare with the situation of using delay line, the signal component in the receiving filter BF2 harmonic wave zone significantly reduces (BF1 ' and BF2 ').
High pass filter, as be expressed as the π type high pass filter of π type equivalent electric circuit shown in Figure 17, or be expressed as the T type high pass filter of T type equivalent electric circuit shown in Figure 180, can be used as phase shifter 6.
That is to say, high pass filter, phase shifter 6 promptly shown in Figure 17 comprises a capacitive element 8, is arranged in transmission line and two inductive elements 7 of extending from public terminal C, lays respectively between two opposite ends of reference potential terminal G and capacitive element 8.
On the other hand, T type high pass filter, phase shifter 6 promptly shown in Figure 180 comprises two capacitive elements 8, is arranged in transmission line and an inductive element 7 of extending from public terminal C, between the mid point and reference potential terminal G of capacitive element 8.
Figure 19 illustrates near the frequency characteristic of phase shifter 6 passband among Figure 17, Figure 20 illustrates the frequency characteristic of phase shifter 6 in the harmonic wave zone among Figure 17, Figure 21 illustrates near the frequency characteristic of phase shifter 6 passband among Figure 18, and Figure 22 illustrates the frequency characteristic of phase shifter 6 in the harmonic wave zone among Figure 18.
Shown in Figure 19 and 21, transmitting filter BF1 and receiving filter BF2 have passband separately, and wherein the passband of receiving filter BF2 is higher than the passband of transmitting filter BF1.Shown in Figure 20 and 22, to compare with the situation of using delay line, the signal component of (being low frequency range, because phase shifter 6 is high pass filters) significantly reduces (BF1 ' and BF2 ') in other frequency band outside passband.
The inductive element 7 of each ground connection can provide the surge voltage tolerance.The capacitive element 8 that each series connection is inserted can cut off DC component.
As mentioned above, the phase shifter of lumped constant element used according to the invention can be used for directly replacing the delay line in the prior art demultiplexer, because phase shifter can provide I/O impedance arbitrarily and phase mass arbitrarily in desired frequency band.
Although comprise that at demultiplexer the situation of two filters described this embodiment, the invention is not restricted to the demultiplexer of double filter class, can also be applied to the multi-filter class demultiplexer that the combination in any by a plurality of filters constitutes.
Under the situation of the demultiplexer of multi-filter type, if see that from the public terminal side input impedance of a junction filter is influential to the impedance the passband of another filter that is connected, then the phase shifter 6 of lumped constant element used according to the invention can be inserted between public terminal and this filter.
From above narration, know and see, can obtain following effect according to the present invention.
That is, can reduce according to the size of demultiplexer of the present invention, because at demultiplexer In the phase shift device that uses used the lump that aspect space efficiency, greatly is better than delay line etc. normal The number element.
Although expectation impedance characteristic and the phase place of demultiplexer can be provided in filter passband Characteristic, but component of signal can decay in being different from other frequency band of this passband. Therefore, can Obtain simultaneously the improvement with the demultiplexer performance of reducing of size.
When using high-pass filter, can also obtain surge tolerance function and direct current cutting function, Thereby can provide multi-functional characteristic.
Claims (13)
1. demultiplexer comprises:
A public terminal;
A plurality of surface acoustic wave filters that are made of surface acoustic wave device have signal terminal and are connected to described public terminal, and passband difference each other; With
A phase shifter that constitutes by lumped constant element, between predetermined one in described public terminal and described surface acoustic wave filter, the coupling between the impedance that the input impedance of this phase shifter is seen to the impedance seen from the public terminal side in the passband of described predetermined surface acoustic wave filter and from described signal terminal side is influential.
2. demultiplexer as claimed in claim 1, wherein said surface acoustic wave device comprises:
By the first surface acoustic wave filter that a surface acoustic wave device constitutes, it has a signal terminal and is connected to described public terminal, and has predetermined passband; With
By the second surface acoustic wave filter that a surface acoustic wave device constitutes, it has a signal terminal and is connected to described public terminal, and has the passband different with the passband of described first surface acoustic wave filter.
3. demultiplexer as claimed in claim 2, wherein said first surface acoustic wave filter forms by this way, that is: a plurality of levels of constituting of series arm resonator of being made by the SAW (Surface Acoustic Wave) resonator that places series arm and the parallel branch resonator that places the SAW (Surface Acoustic Wave) resonator of parallel branch to make are connected, and make that the first order on the described public terminal side is made up of a described series arm resonator; And
Described second surface acoustic wave filter forms by this way, that is: a plurality of levels of constituting of series arm resonator of being made by the SAW (Surface Acoustic Wave) resonator that places series arm and the parallel branch resonator that places the SAW (Surface Acoustic Wave) resonator of parallel branch to make are connected, and make that the first order on the described public terminal side is made up of a described parallel branch resonator.
4. demultiplexer as claimed in claim 1 or 2, wherein said phase shifter is a low pass filter.
5. demultiplexer as claimed in claim 4, wherein said low pass filter are the T type low pass filters that is expressed as T type equivalent electric circuit.
6. demultiplexer as claimed in claim 5, wherein said low pass filter comprises two inductive elements that place a transmission lines that extends from described public terminal, and places a capacitive element between described inductive element mid point and the reference potential terminal.
7. demultiplexer as claimed in claim 4, wherein said low pass filter are the π type low pass filters that is expressed as π type equivalent electric circuit.
8. demultiplexer as claimed in claim 7, wherein said low pass filter comprises an inductive element that places a transmission lines that extends from described public terminal, and place respectively described inductive element opposite end and reference potential end between two capacitive elements.
9. demultiplexer as claimed in claim 1 or 2, wherein said phase shifter is a high pass filter.
10. demultiplexer as claimed in claim 9, wherein said high pass filter are the T type high pass filters that is expressed as T type equivalent electric circuit.
11. demultiplexer as claimed in claim 10, wherein said high pass filter comprises two capacitive elements that place a transmission lines that extends from described public terminal, and places an inductive element between described capacitive element mid point and the reference potential terminal.
12. demultiplexer as claimed in claim 9, wherein said high pass filter are the π type high pass filters that is expressed as π type equivalent electric circuit.
13. demultiplexer as claimed in claim 12, wherein said high pass filter comprises a capacitive element that places a transmission lines that extends from described public terminal, and places two inductive elements between described capacitive element opposite end and the reference potential terminal respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410071336 CN1725638A (en) | 2004-07-20 | 2004-07-20 | Multichannel decomposer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410071336 CN1725638A (en) | 2004-07-20 | 2004-07-20 | Multichannel decomposer |
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| Publication Number | Publication Date |
|---|---|
| CN1725638A true CN1725638A (en) | 2006-01-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200410071336 Pending CN1725638A (en) | 2004-07-20 | 2004-07-20 | Multichannel decomposer |
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|---|---|
| CN (1) | CN1725638A (en) |
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2004
- 2004-07-20 CN CN 200410071336 patent/CN1725638A/en active Pending
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