WO2008129062A1

WO2008129062A1 - Component working with acoustic waves

Info

Publication number: WO2008129062A1
Application number: PCT/EP2008/054928
Authority: WO
Inventors: Andreas Detlefsen; Andreas Waldherr
Original assignee: Epcos Ag
Priority date: 2007-04-24
Filing date: 2008-04-23
Publication date: 2008-10-30
Also published as: DE102007019325B4; DE102007019325A1

Abstract

The invention relates to a component working with acoustic waves, comprising filters (F1, F2) associated with at least two different frequency bands. Each filter has at least one filter stage (A1, A2, B1, B2), wherein different filter stages are realized in separate acoustical tracks or as separate resonator stacks. The component comprises ground connections (GND1, GND2) that are galvanically connected to the ground of the filter stages and provided as exterior connections of the component. A main ground connection is associated with each filter stage, said connection being connected to the respective ground via a main ground path, wherein at least parts of a main ground path are used by at least two filter stages of different filters at the same time.

Description

description

Working with acoustic waves device

A component with acoustic filters is z. B. from the document DE 100 54 968 Al and DE 102005032058 Al known.

From the document DE 196 33 954 Al a filter device is described from at least two filter elements for different frequency ranges. Both filter elements share two shared ground connections.

From the document US 2005/0070332 Al a demultiplexer is known which comprises a reception filter and a transmission filter. Both filters are designed in ladder-type-like structure with parallel resonators in parallel branches. On the ground side, the parallel branches of both filters are interconnected via inductive elements and. In addition, the grounded connections of the parallel branches of the reception filter are electrically connected to those of the transmission filter via an inductive element.

An object to be solved is to specify a working with acoustic waves device that has a small footprint.

It is a working with acoustic waves device, comprising at least two different frequency bands associated filter specified. One of the filters has at least one filter stage and another filter has at least two filter stages, with different filter stages as SAW filter stages (SAW = surface acoustic wave) in separate acoustic tracks or as FBAR filter stage (FBAR = thin film bulk acoustic wave resonator) are realized in separate resonator stacks or in a resonator stack comprising a plurality of resonators. A filter stage can also work with acoustic boundary waves and be designed as a GBAW device (GBAW = guided bulk acoustic wave).

The device has ground connections which are galvanically connected to ground of the filter stages and provided as external terminals of the device.

Each filter stage is associated with a main ground terminal connected to the respective ground via a main ground path. At least parts of a main mass path are used simultaneously by at least two filter stages of different filters.

The main ground path of a filter stage is understood to mean the ground path or the connection of the respective ground with a main ground connection which forms the "path of least resistance", in particular the ground path having the lowest inductance, even if connections of the respective ground to several ground connections are present Thus, there is one main ground path connected to the corresponding ground ground terminal, and if there are several ground paths with the same lowest inductance per filter stage, connecting the ground to a ground terminal, these are all considered to be the main ground terminals.

It is possible that all ground connections are main ground connections. Also, each filter stage with only one ground path can be connected to only one ground terminal, so that a distinction between main ground connections and other ground connections is unnecessary. So it is possible, at least to design a ground connection as the main ground connection of at least two filter stages of different filters.

It is also possible to design at least one ground connection as the main ground connection of at least two filter stages of the same filter.

The total number of ground connections can be smaller than the total number of filter stages. However, it is also possible to provide, in addition to the at least one main ground connection connected to a main ground path, at least one further ground connection which is not connected to a main ground path. One or more such "minor ground connections" can increase the number of ground connections again.

Different filters are preferably different transmission bands, the z. B. may be one octave apart. For example, one filter may be assigned to a frequency band of approximately 1 GHz and the other filter to a frequency band of approximately 2 GHz. For example, the latter frequency band includes transmission bands between 1640 MHz and 2.45 GHz

In a variant, all the filters of the component are provided as receive filters. In a further variant, all the filters of the component are provided as transmission filters. In a further variant, the filters of the component are provided as a transmission-receiving filter. The component can also have multiplexed, ie interconnected, signal-carrying connections which at least in sections have the same signal path. - A -

The respective filter is electrically connected to at least two signal-carrying terminals, which are provided as external terminals of the component. One port serves as the input and the other port as the output of the filter.

The area of the respective ground terminal is preferably not greater than twice the area of the respective signal-carrying terminal. In an advantageous variant, the ratio of the area is a maximum of 1.5. In a further advantageous variant, all external connections of the component are the same size. The arrangement or the pattern of all external connections of the component is referred to below as a footprint. The external connections can be solderable or bondable surfaces. But they can also be realized as bumps, or provided with bumps.

In a variant of the component, the filter stages of a filter comprising several stages are preferably connected in an electrically cascaded manner.

Each filter stage has, in principle, a high frequency filter function, can be a full filter and can be used e.g. have a pass band and stop bands. Different filter stages as well as different filters can be constructed the same or different, i. H. be realized as the same or different types of filters.

At least one of the filter stages comprises transducers operating in a variant with surface acoustic waves. In another variant, at least one of the filter stages comprises resonators operating with bulk acoustic waves. At least one of the filter stages comprises, in a further variant, transducers operating with acoustic interface waves (GBAW Component). The filter levels of different filters may be the same or different.

At least one filter stage may be formed by a single SAW or BAW parallel resonator. The resonator is then connected to another filter stage, the z. B. is formed by a DMS track connected. Two resonators, which together form a basic element of a ladder-type arrangement, are considered together as a filter stage, but not individual resonators of a fundamental element.

The acoustic track of the respective SAW or GBAW filter stage may be formed as a DMS track. DMS stands for Double-Mode Surface Acoustic Wave. At least one input transducer and at least one output transducer may be arranged in the strain gauge track. In one variant, output transducers and / or input transducers can each be replaced by coupling transducers. Two by means of coupling transducers with each other e.g. Cascaded DMS traces, both of which are associated with the same filter, are preferably considered to be different filter stages.

In an advantageous variant, at least two ground paths of the filters, the pass-bands of which lie in different frequency bands, are connected to at least one common main ground path, which is connected to the corresponding associated main ground connection. The masses of the different filter stages of the same filter are preferably conductively connected to different ground terminals. The masses of the different filter stages of the respective filter are independently - in a variant galvanically separated from each other - led to the respective ground terminal. However, it is also possible to de different filter stages of the same filter to merge into a common main ground path and connect to a common main ground connection. However, the galvanic connection between these masses is possible outside of the device.

By merging ground paths of the filters which are permeable in different areas, the number of ground connections and thus the base area of the overall component can be reduced.

Due to the separate ground connection of the filter stages of one and the same filter which are permeable in a common frequency range, it is possible to achieve a particularly high selection in the overall filter, since e.g. the signal cross talk over ground paths is avoided.

In one variant, the respective filter has an input-side filter stage and an output-side filter stage. Masses of the input-side filter stages of different filters are combined to form a common main ground path, which is connected to a first ground terminal. Masses of the output-side filter stages of different filters can likewise be combined to form a common ground path, which is connected to a second main ground terminal.

In a further variant, the mass of an input-side filter stage of a first filter and the mass of an output-side filter stage of a second filter are combined to form a common main ground path, which is connected to a first main ground terminal. The ground paths of an output-side filter stage of the first filter and a Input-side filter stage of the second filter are combined to form a common main ground path, which is connected to a second ground terminal.

The filters are preferably realized at least partially in at least one acoustic chip. Each filter can be realized in a separate chip. It is also possible to realize at least two filters in or on a common chip. The filter stages of the same filter are preferably realized in or on a common chip. Different filter levels of the same filter used in different technologies, eg. B. SAW / BAW, may also be implemented in or on different substrates.

The device comprises e.g. a carrier substrate on which the chip is mounted or a plurality of chips are mounted. The outer terminals of the device, including the ground terminals, are arranged on the underside or the front side of the carrier substrate.

In a further embodiment, in the case of a component without a carrier substrate, the external connections can be realized by bump rows of a BGA (BGA = ball grid array) anchored on the chip.

The merging of masses or better the connection of ground paths of different filter stages can be realized in or on the carrier substrate. Alternatively, the merging of masses of different filter levels is already possible on the chip. The latter is possible if the filters are realized in a common chip. In one variant, at least one of the filter stages comprises an acoustic track with at least two acoustically coupled transducers. At least one of the filter stages may also be designed as a ladder-type arrangement of transducers. The ladder type arrangement has at least one series branch and at least one shunt branch connected to the series branch, a series converter being arranged in the series branch and a parallel converter being arranged in the shunt branch.

In one variant, at least one of the filter stages comprises a stack of superposed, acoustically coupled BAW resonators (BAW = bulk acoustic wave). A ladder type arrangement of BAW resonators is also possible. In this case, at least one of the filter stages has at least one series branch and at least one shunt branch connected to the series branch, wherein a series resonator is arranged in the series branch and a parallel resonator is arranged in the transverse branch, which together form a basic element that represents a filter stage.

An input-side matching network for adapting the input impedance of the respective filter to a specific impedance level can be arranged in the carrier substrate. An output matching network for adapting the output impedance of the respective filter to a specific impedance level can be arranged in the carrier substrate. The respective matching network has at least one passive element selected from a series capacitance, shunt capacitance, series inductance and a shunt inductance.

The input and / or the output of the respective filter can be single-ended. The entrance and / or the output of the respective filter can also be differential (balanced).

In the following, the specified component and its advantageous embodiments will be explained with reference to schematic and not to scale figures. Show it:

Figure 1 shows the equivalent circuit of a device with two filters, in which the masses of the input and output side filter stages are brought together;

FIG. 2 shows the equivalent circuit diagram of a component with two filters, in which the masses of the input and output filter stages of different filters are combined;

3 shows in cross-section the component in which the masses of different filter stages are brought together in the carrier substrate;

FIG. 4 shows the equivalent circuit diagram of a component with two filters, in which the conductor sections which contribute to the ground paths, together with the associated inductances, are shown;

Figures 5, 6 each show the view of an exemplary footprint of the device.

Figures 1, 2 each show a component with two filters Fl, F2, which are arranged in a common housing or on a common carrier substrate TS.

The first filter Fl has an input-side filter stage Al and an output-side filter stage A2. The second FiI- ter F2 has an input-side filter stage Bl and an output-side filter stage B2.

The input-side filter stage Al of the first filter Fl is connected in FIG. 1 to an input terminal IN _a and in FIG. 2 to two input terminals IN _a i, IN _a2 . The output-side filter stage A2 of the first filter Fl is connected in FIG. 1 to an output terminal OUT _a and in FIG. 2 to two output terminals OUT _a i, OUT _a2 . This applies correspondingly to the input-side filter stage Bl and the output-side filter stage B2 of the second filter F2 and the input terminals IN _b , IN _b i, IN _b2 and output terminals OUT _b , OUTbi, OUT _b2 .

In the variant according to FIG. 1, the masses of the input-side filter stages A1, B1 are combined and connected to a common ground terminal GND1. The masses of the output-side filter stages A2, B2 are merged and connected to a common ground terminal GND2.

In the variant according to FIG. 2, the mass of the input-side filter stage A1 of the first filter F1 is combined with the mass of the output-side filter stage B2 of the second filter F2 and connected to a common ground terminal GND1. The mass of the input-side filter stage Bl of the second filter F2 is merged with the ground of the output-side filter stage A2 of the first filter Fl and connected to a common ground terminal GND2. At least in sections, the corresponding filter stages are connected via the same ground path to a ground terminal, which represents the main terminal for the corresponding filter stages. The total number of filter stages of the device is four. In both variants shown, the number of ground connections is two and is thus smaller than the total number of filter stages of the component.

The carrier substrate TS comprises at least two dielectric layers and metallization planes arranged alternately therewith. On the underside of the substrate are external terminals of the device and on top of the substrate contacts for contacting of at least one chip, in which the filters Fl, F2 are realized arranged.

FIG. 3 shows a variant in which the filters F1, F2 are implemented in separate acoustic chips. The merging of the masses of the filter stages takes place in an inner plane of the carrier substrate TS.

The component is preferably suitable for SMD mounting and has the outer terminals in the form of a metal layer applied to the underside of the carrier substrate.

FIG. 4 shows the equivalent circuit diagram of a component with two filters F1, F2, of which two filter stages A1, A2 or B1, B2 are shown here and one third filter stage A3, B3 each is indicated. The picture explains the definition of the main mass paths and main ground connections.

Each ground path consists of conductor sections and also includes all electrical connections between the ground on the filter structure and the respective ground terminal on the underside of the substrate. These include, for example, bumps and through-contacts and other elements. For simplicity, these elements are in the equivalent circuit diagram as inductors Ll to L5. shown. For the sake of clarity, only the ground paths of the first two filter stages Al and Bl are considered. The other ground paths may be similarly constructed and interconnected.

Ground paths for the filter stage Al e.g. are all possible rungs between Al and a ground connection. The main ground path is the one having the least total inductance in the sum of the single inductances. For the filter stage Al, this may be the path through Ll, L2 and L3 to GND2, if (L2 + L3) is less than L5. Then, the main ground path for the filter stage Bl via L4 and L3 also goes to the ground terminal, since L5> (L2 + L3). GND2 is then the main ground connection for the two filter stages Al and Bl. The further ground paths from Al via Ll and L5 to GNDl and from Bl via L4, L2 and L5 are then "secondary ground paths" with higher total inductance than the respective main ground paths Inductance L3 is common to both main ground paths, here represented on the carrier substrate realized elements of the ground paths, of course, all sections of the corresponding electrical connections, which can also be realized on the filter chips, or the connection of the ground paths filter stages of two different filters already on take place on or on one of the filter chips.

Various variants of a footprint of the above-described device with four filter stages are shown in FIGS. 5 and 6. In the variant according to FIG. 5, the ground connection GND1 is arranged between the input connections IN _a , IN _{b of} the first and second filters F1, F2. Ground terminal GND2 is between the output terminals OUT _a , OUT _{b of} the first and second filters Fl, F2 arranged.

In the variant according to Figure 6, the ground terminal GNDL between the terminals IN _a, _a OUT is disposed the first filter Fl and the ground terminal GND2 between the terminals in _B, OUT _b of the second filter F2.

The surface of the respective ground connection can, in all variants, as indicated in FIG. 5, be equal to the area of the signal-carrying connections. Alternatively, as indicated in FIG. 6, the area of the ground connections may be slightly larger than the area of the signal-carrying terminals. However, the ratio of these areas is preferably at most 1.5. This has the advantage that the dosage of the solder mass and thus the quality of the solder joint of the respective terminal z. B. can be controlled particularly well with a circuit board.

The number of filters and filter stages in the component is not limited to the variants explained in the figures. The number of dielectric layers in the carrier substrate can also be arbitrary.

LIST OF REFERENCE NUMBERS

Fl first filter

F2 second filter

Al input side filter stage of the first filter Fl

A2 output-side filter stage of the first filter Fl

Bl input side filter stage of the second filter F2

B2 output-side filter stage of the second filter F2

GNDl, GND2 ground connections

IN _a , IN _a i, IN _a 2 Input terminals of the first filter Fl

OUT _a , OUT _a i, OUT _a2 Output _{terminals of} the first filter Fl

IN _b , INbi, IN _b 2 input terminals of the second filter F2

OUT _b , OUT _b i, 0 OUT _b 2 output terminals of the second filter F2

TS carrier substrate

Ll, L2, ... L5 inductors in the ground path

Claims

claims

1. Working with acoustic waves device

comprising filters (Fl, F2) associated with at least two different frequency bands,

wherein one of the filters has at least one filter stage (A1, A2) and another filter has at least two filter stages (B1, B2), wherein different filter stages are realized in separate acoustic tracks or as separate resonator stacks,

- With ground terminals (GNDL, GND2), which are galvanically connected to ground of the filter stages and provided as external terminals of the device, each filter stage is associated with a main ground terminal, which is connected to the respective ground via a main ground path, wherein at least parts of a Hauptmassepfad simultaneously at least two filter stages of different filters are used.

2. The component according to claim 1, wherein at least one ground connection is designed as the main ground connection of at least two filter stages of different filters.

3. The component according to claim 1, wherein at least one ground connection is designed as the main ground connection of at least two filter stages of the same filter.

4. The component according to one of claims 1-3, wherein, in addition to the at least one main ground connection connected to a main ground connection at least one further Ground connection is present, which is not connected to a main ground path.

5. Component according to one of claims 1-4,

wherein the respective filter is electrically connected to at least two signal-carrying terminals (IN _a , IN _b , OUT _a , OUT _b ), which are provided as external terminals of the component,

- Wherein the surface of the respective ground terminal (GNDL, GND2) is not greater than twice the area of the respective signal-carrying terminal (IN _a , IN _b , OUT _a , OUT _b ).

6. Component according to one of claims 1-5,

- Wherein at least two filter stages of the respective filter (Fl, F2) are connected electrically cascaded.

7. The component according to one of claims 1 to 6,

- Wherein the main ground paths of two different filters, the pass bands are in different frequency bands, at least partially and at least partially coincide and are connected to a common main ground connection.

8. Component according to one of claims 1 to 7,

- Wherein the main ground paths of different filter stages of the same filter with different main ground connections are conductively connected.

9. The component according to claim 8,

- Wherein the main mass paths of the different filter stages of the respective filter are galvanically separated from each other to the respective main ground connection.

10. The component according to one of claims 1 to 9,

- wherein the respective filter (Fl, F2) has an input-side filter stage (Al, Bl) and an output-side filter stage (A2, B2),

- Wherein ground paths of the input-side filter stages (Al, Bl) of different filters to a common ground path, which is connected to a first main ground terminal, merged,

- Wherein ground paths of the output side filter stages (A2, B2) of different filters to a common ground path, which is connected to a second main ground terminal, merged.

11. The component according to one of claims 1 to 9,

wherein a ground path connected to the ground of an input side filter stage of a first filter and a ground connected to the ground of an output side filter stage of a second filter are merged to a common ground ground path connected to a first main ground terminal (GND1);

wherein a ground path connected to the ground of an output side filter stage of the first filter and a ground connected to the ground of an input side filter stage of the second filter are merged to a common ground ground path connected to a second main ground terminal (GND2).

12. Component according to one of claims 1 to 11,

- With a carrier substrate (TS) and at least one acoustic chip, which on the top of the carrier substrate mon- t is

- wherein the filters (Fl, F2) are realized at least partially in or on the at least one chip,

- Wherein the ground terminals (GNDL, GND2) and signal-carrying terminals (IN _a , IN _b , OUT _a , OUT _b ) of the filter on the underside of the carrier substrate (TS) are arranged.

13. Component according to one of claims 1 to 12,

- Wherein the merging of masses of different filter stages is realized on the chip.

14. Component according to one of claims 1 to 12,

- Wherein the combination of ground paths of different filter stages in the carrier substrate (TS) is realized.

15. Component according to one of claims 1 to 14,

- Wherein at least one of the filter stages (Al, A2, Bl, B2) comprises acoustic surface acoustic waves transducer operates.

16. Component according to claim 15,

- Wherein at least one of the filter stages (Al, A2, Bl, B2) comprises an acoustic track with at least two acoustically coupled transducers, and / or

- Wherein at least one of the filter stages has at least one series branch and at least one connected to the series branch transverse branch, wherein in the series branch a series converter and in the transverse branch a parallel converter is arranged.

17. Component according to one of claims 1 to 16,

- Wherein at least one of the filter stages (Al, A2, Bl, B2) comprises working with bulk acoustic waves resonators.

18. Component according to claim 17,

wherein at least one of the filter stages comprises a stack of acoustically coupled resonators arranged above one another, and / or

- Wherein at least one of the filter stages has at least one series branch and at least one connected to the series branch transverse branch, wherein in the series branch a series resonator and in the transverse branch a parallel resonator is arranged.