Abstract:
A component operating with acoustic waves is described herein. The component includes a substrate having an underside subdivided into a center area and an edge area surrounding the center area on all sides. The component also includes a plurality of outer terminals in the edge area, and a plurality of inner terminals in the center area comprising at least a first inner terminal configured as a signal terminal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Pursuant to 35 USC §120, this application claims the benefit of PCT/DE2006/002014 filed Nov. 16, 2006 which claims the benefit of German Patent Application No. 102005056340.6 filed Nov. 25, 2005. Each of these applications is incorporated by reference in its entirety. 
     BACKGROUND 
     Components operating with acoustic waves are known for instance from the publication U.S. Pat. No. 6,791,437 B2. 
     SUMMARY 
     A problem to be solved is to specify a component with a low crosstalk between two signal paths to be separated from one another. 
     According to a first preferred embodiment, a component operating with acoustic waves is specified comprising a substrate, the underside of which is divided into an edge area and a center area surrounded on all sides by the latter. Outer terminals are arranged in the edge area and an arrangement of inner terminals is arranged in the center area. The arrangement of inner terminals comprises at least one first inner terminal, which is provided as a signal terminal. 
     The terminals of the component are also referred to as pins or solder pads. Terminals that are arranged in two mutually perpendicular preferred directions between two other terminals of the pattern of terminals, known as a footprint, are referred to as inner terminals. The preferred directions are, for example, defined parallel to the edges of the substrate&#39;s underside. Those terminals which are arranged in the edge area of the substrate underside (or outside the center area) are referred to as outer terminals. 
     In one variant, the arrangement of inner terminals has at least one second inner terminal which is provided as a ground terminal. A (first or second) inner terminal is positioned such that that it lies in each of two mutually perpendicular directions between two other terminals, e.g., between two outer terminals. 
     The substrate is, for example, a multilayer substrate with metallization planes, between which dielectric layers are arranged. The substrate is an LTCC substrate, for example. A chip having components operating with surface acoustic waves and/or bulk acoustic waves is preferably mounted on the substrate. 
     In one variant, a duplexer circuit that comprises a transmit filter and a receive filter is in the component. These filters have acoustic resonators that are arranged in the chip or on the chip, for example. The filters are electrically connected to the inner and the outer terminals of the component via electrical connections integrated into the substrate. The duplexer circuit can have an antenna-side matching network, e.g., a transmission line arranged in the receive path. This matching network is preferably integrated into the substrate, with its LC elements or line segments being realized, for instance, by conductor tracks or conductor areas arranged in the metallization planes. 
     According to the second preferred embodiment, a component operating with acoustic waves is specified, comprising a substrate, on the underside of which first signal terminals and second signal terminals are arranged. The center points of the at least two second signal terminals lie substantially on an imaginary center line that runs in the center between two first signal terminals. 
     The first signal terminals are preferably assigned to a balanced port that is connected, for example, to a receive path with symmetrical signaling. The second terminals are preferably each assigned to a single-ended port. 
     In one variant, the component comprises a duplexer with an antenna terminal, a transmit input and a receive output. The receive output is preferably assigned to the balanced port. One of the second signal terminals is provided as an antenna terminal, the other second signal terminal being assigned to the transmit input. 
     The arrangement of the antenna terminal between the signal terminal of the transmit path and the signal terminals of the receive path is considered advantageous. 
     A first ground terminal can be arranged between the antenna terminal and the signal terminal of the transmit input. A second ground terminal can be arranged between the antenna terminal and the signal terminals of the receive output. Preferably each of these ground terminals has a larger surface area than the first and second signal terminals. Additional inner or outer ground terminals can also be provided, preferably also having a larger surface area than the signal terminals. Additional signal terminals can also be present. 
     In one variant, the terminals comprise two successive terminals with different surface areas, wherein the terminal with a smaller surface area is provided as a signal terminal, and the terminal with the larger surface area is provided as a ground terminal. The terminals comprise for example, at least two successive terminals with differing widths, wherein the terminal with the smaller width is provided as a signal terminal and the terminal with the greater width is provided as a ground terminal. 
     According to the second preferred embodiment, a component operating with acoustic waves is specified, comprising a substrate, the underside of which comprises at least three terminals arranged one alongside the other in a preferred direction, wherein at least two of these terminals have widths differing from one another relative to the preferred direction. The ratio of the differing widths lies between 1 and 2 in an advantageous variant, but can in principle also be greater than two. 
     A grounding surface, which is arranged in the substrate and is provided for shielding the circuit elements integrated into the substrate (in particular, the matching network of the duplexer), can be connected to a ground terminal. A grounding surface, for example arranged on the rear side of the chip that is provided for shielding the component structures integrated in the chip can also be connected to a ground terminal. 
     The terminal with the smaller surface area or width can be provided in all preferred embodiments of the component as a signal terminal, and the terminal with the larger surface area can be provided as a ground terminal. It is advantageous to select an average size of the terminals provided as signal terminals to be smaller than an average size of the terminals provided as ground terminals. 
     The terminals arranged on the underside of the component can be suitable for surface mounting in all preferred embodiments. 
     In all preferred embodiments of the component, the underside of the carrier substrate can comprise an arrangement of terminals arranged one alongside the other in one direction, wherein the distances between successive terminals can differ from one another. It is provided that, in particular, relative to at least one preferred direction, the distance between a signal terminal and the adjacent terminals (ground terminals or at least one additional signal terminal) is selected to be greater than the distance between two ground terminals arranged one alongside the other relative to a preferred direction. 
     The arrangement of terminals arranged one alongside the other in a preferred direction can optionally have terminals that are offset with respect to one another perpendicular to the preferred direction, so that their centers do not lie on one line. It is also possible, however, for the terminals of this arrangement to form a row, wherein their centers or edges (e.g., edges facing inward or outward with respect to the center of the substrate) lie on an imaginary line. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The specified component will be described below on the basis of schematic figures not drawn to scale. 
         FIG. 1  shows the plan view onto the underside of the component, and its subdivision into an edge area and a center area; 
         FIG. 2 , an example of a footprint with a pin matrix having inner terminals; 
         FIG. 3 , a component in cross section with an acoustic chip that is mounted on a carrier substrate, on the underside of which inner terminals are provided; 
         FIG. 4 , a circuit with a duplexer realized in the component according to  FIGS. 2 ,  3 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an imaginary subdivision of the underside of a carrier substrate TS, shown in  FIG. 3  for instance, with an edge area RB and a center area MB. Edge area RB is an area having the shape of a frame that faces the outer edges of the carrier substrate. Edge area RB is an area that is free of inner terminals IA 1 , IA 2 . On the other hand, the center area is an area that is free of outer terminals AA. Terminals AA, IA 1  and IA 2  are SMD terminals. 
       FIG. 2  shows the footprint (terminal arrangement) of a component operating with acoustic waves in which a duplexer circuit is realized. The footprint is realized in the lowermost metallization plane of substrate TS. 
     Outer terminals AA are arranged in edge area RB, and a first inner terminal IA 1  and several second inner terminals IA 2  are arranged in center area MB. The ratio of the widths of the center area and the edge area can in principle be arbitrary. The width of the edge area is substantially determined by the length of the outer terminals AA, or the longest of these terminals. The connecting points between terminals IA 1 , IA 2  and contact areas, not shown in the figures, of an external circuit board can be solder pads or bumps, for example. 
     Terminal IA 1  is a signal terminal and terminals IA 2  are ground terminals. Terminal IA 1  in this case is an antenna terminal ANT. All terminals form a footprint in the form of a pin matrix that has several rows and five columns. 
     Successive terminals in the horizontal direction form a row and successive terminals in the vertical direction form a column. For example, the successive terminals GND, GND 1 , GND 6  and GND 2  form one row and the terminals TX, GND 1 , ANT and GND 2  form an additional row. Terminals GND 1 , GND 2  and RX 1  follow one another in a horizontal direction and therefore form a row. In principle the columns can be interchanged with the rows in case of a rotation of the footprint by 90°, for example. 
     The first ground terminal GND  1  serves to shield antenna terminal ANT from the unbalanced-to-ground transmit input, which has a signal terminal TX. The second ground terminal GND 2  serves to shield antenna terminal ANT from the ground-symmetric receive output, which has two signal terminals RX 1 , RX 2 . 
     Additional ground terminals, including terminals GND 3 , GND 4 , GND 5 , are provided. Apart from the signal terminals RX 1 , RX 2 , TX and ANT, all other terminals are preferably connected to ground. The surface area of the signal terminals RX 1 , RX 2 , TX and ANT is smaller than the surface area of the ground terminals. It is possible for example, to select the width L 1  of signal terminal TX, measured in the vertical direction, to be smaller than the width L 2  measured in this direction of the ground terminals GND, GND 3  adjacent to this signal terminal. 
     The distance between signal terminal TX and the adjacent terminals GND, GND 1 , GND 3  is preferably larger than the distance between two ground terminals, e.g., between terminals GND and GND 1  or GND 4  and GND 5 . This also applies to the signal terminals ANT, RX 1  and RX 2 . 
     The surface area of the ground terminals GND 1 , GND 2  provided between two hot terminals is selected to be greater than the surface area of other ground terminals, which serve, for instance, for ground contact with a ground contact area in substrate TS. 
     The dimensioning and positioning of the terminals of a footprint explained in connection with  FIG. 2 , in particular, the relative dimensioning and positioning of the signal and ground terminals, represent measures according to the third preferred embodiment of the component. 
     The footprint shown in  FIG. 2  has, according to the second preferred embodiment of the component, first signal terminals  11 ,  12  and second signal terminals  21 ,  22 . The center points of second signal terminals  21 ,  22  lie on an imaginary center line ML that runs in the middle between two first signal terminals  11 ,  12 . 
     The first terminals are preferably equally large and are mirror-symmetrically arranged relative to line ML, which runs through the centers of second terminals  21 ,  22 . Thus the same distance of the two first terminals  11 ,  12  from terminal  21  and from terminal  22  is guaranteed. 
     First terminals  11 ,  12  in the variant according to  FIG. 2  are signal terminals RX 1 , RX 2  of a first ground-symmetric receive output. Second terminal  21  is a signal terminal TX of an unbalanced-to-ground transmit input. The additional second terminal  22  is an antenna terminal ANT, thus also a signal terminal of an unbalanced-to-ground electric port. 
       FIG. 3  shows an example of a component in cross section. The component comprises a substrate TS and a chip CH arranged thereon which comprises component structures operating with acoustic waves. 
     Substrate TS comprises several dielectric layers, e.g., LTCC layers. The dielectric layers of the substrate are arranged between metallization planes. The metallization planes are conductively connected to one another by means of plated through-holes. The metallization planes comprise circuit elements such as inductors, capacitors, or transmission lines, including the transmission line TL shown in  FIG. 4 . 
     The outer and inner terminals AA, IA 1 , IA 2  of the component, which were already shown in  FIG. 2 , are formed in the lowest metallization plane of carrier substrate TS. In its uppermost metallization plane, contact areas are formed which can be connected to the terminal areas of chip CH by means of bumps in a flip chip arrangement of chip CH. The electrical connection between the contact areas of carrier substrate TS and the terminal areas of chip CH is alternatively possible by means of bond wires, in case the rear side of the chip faces towards the carrier substrate. 
       FIG. 4  shows a front end circuit with a signal path that comprises an antenna path (transmit-receive path) connected to an antenna terminal ANT, a transmit path connected to a transmit input TX and a receive path connected to a receive output RX 1 , RX 2 . 
     Duplexer DU comprises a transmit filter F 1  arranged in the transmit path, a receive filter F 2  arranged in receive path RX, and a matching network that can comprise a transmission line TL arranged in the receive path. 
     Transmission line TL preferably has a quarter wavelength at the transmit frequency associated with the signal path. A λ/4 line emulated by LC elements can be used in place of transmission line TL. These LC elements are preferably integrated in substrate TS. Alternatively the matching network can also have, for instance, a parallel inductor and a series capacitor. 
     The filters F 1 , F 2  associated with duplexer DU each comprise BAW resonators and/or at least one SAW transducer. The resonators or transducers can be interconnected in a ladder-type arrangement, for example. 
     A balun is integrated in receive filter F 2  in the variant shown in  FIG. 4 . It is also possible to connect a balun, which is preferably integrated in substrate TS, on the output side of receive filter F 2  with a single-ended output. 
     Different measures explained above for designing a footprint can be arbitrarily combined with one another.