Package for a Tunable Filter

Abstract

A package for a tunable filter is disclosed. In an embodiment, the tunable filter includes a substrate having a first interconnection plane and a semiconductor device assembled on the substrate in a first component plane, the semiconductor device electrically connected to the first interconnection plane and containing tunable passive components. The filter further includes a control unit arranged in the first component plane, a dielectric layer arranged above the first component plane, a second component plane arranged on the dielectric layer and discrete passive devices arranged in the second component plane and interconnected with the semiconductor device, wherein the tunable passive components are tunable by the control unit.

Claims

1-21. (canceled)

22. A package for a tunable filter, the package comprising: a substrate comprising a first interconnection plane; a semiconductor device assembled on the substrate in a first component plane, the semiconductor device electrically connected to the first interconnection plane and containing tunable passive components; a control unit arranged in the first component plane; a dielectric layer arranged above the first component plane; a second component plane arranged on the dielectric layer; and discrete passive devices arranged in the second component plane and interconnected with the semiconductor device, wherein the tunable passive components are tunable by the control unit, and wherein the tunable passive components, the control unit and the discrete passive devices realize the filter which is tunable in respect of a passband.

23. The package according to claim 22, wherein the tunable passive components are tunable capacitors, wherein the tunable capacitors are selected from varactors and switchable capacitances, and wherein the discrete passive devices are inductances.

24. The package according to claim 23, wherein the tunable capacitors are embodied as an array of switchable MEMS capacitors or switchable MIM capacitors.

25. The package according to claim 23, wherein the inductances are embodied as SMD components, each having a magnetic axis, wherein the SMD components are arranged linearly in such a way that magnetic axes of two SMD components arranged next to one another are rotated by approximately 90° with respect to one another.

26. The package according to claim 22, further comprising a serial signal line, wherein the serial signal line has at least 4 circuit nodes, wherein a parallel branch is coupled between a circuit node and ground for each node, and wherein a tunable reactance element is arranged in each parallel branch.

27. The package according to claim 26, wherein a coupling capacitance is arranged in the serial signal line between respectively two adjacent circuit nodes.

28. The package according to claim 27, wherein the circuit nodes arranged at an end on both sides of the serial signal line are connected via a bridging inductance connected in parallel with the serial signal line.

29. The package according to claim 28, wherein a coupling inductance is arranged in place of the coupling capacitance in the serial signal line between respectively two adjacent circuit nodes.

30. The package according to claim 28, wherein end circuit nodes of the at least 4 circuit nodes are connected by a bridging capacitance connected in parallel with the serial signal line.

31. The package according to claim 28, wherein the coupling capacitances and the bridging inductance are embodied as an integrated passive element (IPD) and arranged in the first component plane.

32. The package according to claim 31, wherein the substrate or the integrated passive element is selected from an LTCC or HTCC ceramic or a laminate.

33. The package according to claims 28, wherein the coupling capacitances and the bridging inductance are integrated into the semiconductor device.

34. The package according to claim 26, wherein the reactance element is a parallel resonant circuit, wherein each parallel resonant circuit comprises a parallel connection of a tunable capacitor and an inductance.

35. The package according to claim 26, wherein the reactance element is a series inductance.

36. The package according to claim 26, wherein the reactance element is a tunable capacitance.

37. The package according to claim 26, wherein the reactance element is a series connection of a tunable capacitance and an inductance.

38. The package according to claim 26, wherein the reactance element is a series connection of an admittance inverter and a tunable capacitance.

39. The package according to claim 22, wherein the control unit is integrated into the semiconductor device together with the tunable passive components.

40. The package according to claim 22, wherein all external contacts are arranged on a lower surface of the substrate facing away from the first component plane, and wherein the external contacts and the tunable filter are electrically contacted by via holes and conductor tracks.

41. The package according to claim 22, wherein passive components of the tunable filter are integrated into the substrate.

42. The package according to claim 22, further comprising further components integrated into the package and arranged in the first or second component plane, wherein the further components are selected from the group consisting of a power amplifier, an LNA, an acoustic filter, a duplexer, a diplexer and an RF semiconductor device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Below, the invention is explained in more detail on the basis of exemplary embodiments and the associated figures.

[0049] The figures only serve for the better understanding of the invention and are therefore only schematic and not necessarily embodied true to scale. Therefore, it is not possible to gather either relative or absolute dimensional specifications from the figures. The same or equally acting parts are provided with the same reference signs.

[0050] FIG. 1 shows a schematic cross section of a package for, and with, a tunable filter.

[0051] FIGS. 2A to 2D show four embodiments of tunable filters in a block diagram.

[0052] FIGS. 3A and 3B show a possible separation of components of a tunable filter.

[0053] FIGS. 4A to 4C show a further possible separation of components of a tunable filter.

[0054] FIG. 5 shows a package with a tunable filter in a schematic cross section.

[0055] FIG. 6 shows an array of tunable impedance elements and a control unit.

[0056] FIG. 7 shows an array of switchable capacitances or capacitors.

[0057] FIG. 8 shows an arrangement of inductive components, which are distinguished by low coupling.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0058] FIG. 1 shows a simple exemplary embodiment of a package according to the invention. The package is built up on a substrate S, which is a single-layer or multi-layer substrate and has at least one interconnection plane SE1. The interconnection plane SE1 can be embodied on the surface of the substrate S or, as depicted in FIG. 1, between two insulating layers of a multi-layer substrate. At least one semiconductor device HLB is assembled on the substrate and electrically connected to the first interconnection plane SE1. In addition to the semiconductor device HLB, further discrete, integrated or other devices (not depicted in the figure) can be arranged on the substrate in the first component plane KE1. The semiconductor device HLB comprises at least high-quality tunable passive components.

[0059] A control unit can be integrated into the semiconductor device HLB. A control unit can also be realized as a further separate semiconductor device and arranged in the first component plane KE2.

[0060] The devices of the first component plane are covered by a dielectric layer DS or embedded in a dielectric layer DS, which terminates to the top with an approximately plane surface. A second component plane KE2 is provided above the dielectric layer DS and the first component plane KE1, which is arranged covered below, or embedded within, said dielectric layer. Discrete, high-quality passive devices DP are arranged in said second component plane. The discrete high-quality passive devices DP are electrically interconnected with the components of the first component plane KE1. This can be carried out directly by way of via holes from the devices of the second component plane to the contacts of the semiconductor devices HLB in the first component plane. However, as depicted in the figure, it is also possible to provide a second interconnection plane SE2 between the first component plane KE1 and the second component plane KE2. The line sections of the second interconnection plane SE2 are electrically connected to the corresponding contacts of the discrete passive devices DP and, moreover, to contacts of the semiconductor devices by means of via holes. The second interconnection plane SE2 can be embedded between two layers of a dielectric.

[0061] External contacts AK are provided at the lower side of the substrate S, which external contacts are connected by way of via holes DK either directly to the components of the first component plane KE1 or, as depicted in the figure, to the first interconnection plane SE1.

[0062] Further passivations or protective covers, which seal the components of the package P against environmental influences, are not depicted in FIG. 1. By way of example, such a passivation can be at least one layer deposited on or applied directly to the surface of the discrete passive devices DP, in particular a thin film. The passivation can also comprise a layer sequence of deposited or applied layers. By way of example, it is possible to apply a first interlocking cover to the discrete passive devices DP, which cover terminates with the surface of the dielectric layer DS. By way of example, this can be a thermoplastic film. This film can subsequently be provided with a metalization, which can optionally still be reinforced in an electrolytic or electroless manner.

[0063] It is also possible to enlarge the surface of the substrate S in relation to the region provided with components and to let the passivation terminate with the substrate surface which then protrudes. Furthermore, it is possible to place a rigid and mechanically dimensionally stable cap onto the surface of the dielectric layer DS or onto protruding surface regions of the substrate S and seal it against the latter. There can subsequently still be encapsulation of the entire package P, both in the case of an interlocking cover and in the case of a rigid cap, with, advantageously, either a glob top compound being applied or the entirety being injection molded with a plastic compound, e.g. by overmolding.

[0064] FIG. 2 shows various embodiments of tunable filters. Only exemplary topologies are depicted, and so further embodiments are conceivable. FIG. 2A shows a bandpass filter, which connects a first terminal Ti to a second terminal T2 using a serial signal line SL. At least four circuit nodes N, to which reactance elements are coupled, are provided in the serial signal line SL. A coupling capacitor KC is connected between in each case two circuit nodes N, by means of which coupling capacitor the reactance elements are coupled to one another. A bridging inductance BI is interconnected parallel to the serial signal line between the two outermost circuit nodes N of the serial signal line SL.

[0065] For a bandpass filter like in FIG. 2A, the reactance element is embodied e.g. as a parallel resonant circuit, in which a high-quality tunable capacitance CT is interconnected with a high-quality parallel coil PL up to ground. Together with the bridging inductance BI, the four parallel resonant circuits generate a filter with a transfer behavior, which has two poles which span between them a passband of the bandpass filter. It is also possible to integrate further parallel resonant circuits in a bandpass filter in the manner shown, by means of which further poles can be embodied or the available poles can be amplified.

[0066] The terminal capacitors AC serve to set an input impedance or an output impedance. Thus, for example, an input impedance of 5 Ω can be set by a terminal capacitor AC with a capacitance of 5 pF in one exemplary embodiment. By raising this capacitance value to e.g. 18 pF, it is possible to set an input impedance of 50 Ω without there being a substantial change in the transfer behavior of the filter circuit in the process. However, small adaptations of the values of other components may be required.

[0067] FIG. 2B shows a low-pass filter which, like the bandpass filter in FIG. 2A, has a serial signal line SL, four circuit nodes with coupling capacitances arranged therebetween and two terminal capacitances AC at the ends. At the circuit nodes, high-quality tunable capacitors are connected up to ground as reactance elements.

[0068] In a block diagram, FIG. 2C shows a tunable filter which is embodied as a high-pass filter. In contrast to the low-pass filter in FIG. 2B, the high-pass filter in FIG. 2C has high-quality inductances as reactance elements. Using tunable high-quality inductances I, it is also possible to embody the high-pass filter as a tunable filter.

[0069] FIG. 2D shows a block diagram of a tunable filter embodied as a bandstop filter. Here, series resonant circuits are coupled to the circuit nodes N of the serial line SL as reactance elements, which series resonant circuits comprise a high-quality tunable capacitance CT and, connected in series therewith, a high-quality inductance I. The bandstop filter can be embodied as a notch filter, in which individual frequencies are damped but there is a good pass with little damping in the rest of the range. However, it is also possible for the series resonant circuits SK, which are coupled to one another by way of the coupling capacitors KC, to span a stop band together. Then, the bandstop filter exhibits a good pass behavior in the remaining frequencies on both sides of the stop band.

[0070] FIG. 2E shows, in a block diagram, a tunable high-pass filter which is realized using admittance inverters AI. In contrast to the low-pass filter in FIG. 2B, the high-pass filter in FIG. 2E in each case has a series connection of an admittance inverter AI and a tunable capacitance CT as tunable reactance elements.

[0071] In the embodiments of filters depicted in FIGS. 2A to 2E, the components of the reactance elements are embodied as high-quality components. By way of example, the tunable high-quality capacitors CT are integrated into a semiconductor device HLB and embodied as varactors or switchable capacitors. The inductances in the reactance elements of FIGS. 2A, 2C and 2D are also of high quality and are, in particular, embodied as discrete passive devices DP (see FIG. 1). The remaining passive components within the serial signal line SL, and the bridging inductance BI, can be low-quality components. The admittance inverters AI of the circuit in FIG. 2E are also preferably embodied an interconnection of high-quality passive components.

[0072] As already indicated in FIG. 1, an advantageous refinement of the invention consists of separating low-quality and high-quality passive components from one another. FIGS. 3A and 3B show, in an exemplary manner, a possible separation of the components for a bandpass filter as depicted in FIG. 2A. In this case, the tunable capacitances CT are combined in one group, integrated on a device or realized in a separate region of a semiconductor device. The low-quality passive components can be realized on an integrated passive device (IPD), which can be arranged like a discrete device in the first or second component plane KE1, KE2 of the package P, as depicted in FIG. 1.

[0073] In a further embodiment of the invention, the passive components are subdivided further. A first group of passive components comprises the coupling capacitors and the bridging inductance as in FIG. 4A. The high-quality inductances of the reactance elements in FIGS. 2A, 2C, 2D and 2E form a further group of passive components, which are realized separately, for example as passive discrete devices PD. The tunable capacitances CT in exemplary embodiments 2A, 2B, 2D and 2E form a further group of passive components realized separately, which are integrated into the semiconductor device HLB. Only the high-quality inductances PL, I of FIG. 4B are embodied completely separately and preferably as individual discrete devices.

[0074] Low-quality passive components and the tunable capacitors of FIG. 4C can be realized separately, for example the tunable capacitances can be realized as a semiconductor device and the low-quality components as an integrated passive device. However, alternatively, it is also possible for the components in FIGS. 4A and 4C to be realized in a common semiconductor device. Furthermore, it is possible to integrate the low-quality passive components into a multi-layer substrate S.

[0075] FIG. 5 shows a schematic cross section of a package which has at least two semiconductor devices HLB1, HLB2 in the first component plane. The individual components as per FIGS. 3B, 4C and 4A can be divided among these two semiconductor devices. Additionally, the control unit can be integrated in one of the two semiconductor devices, which control unit can be embodied as a MIPI-RFFE controller (=mobile industry processor interface—radiofrequency front-end). The MIPI controller, i.e. the control unit, can also be embodied as a separate semiconductor device in the first component plane KE1. In a further embodiment, all passive components with the exception of the high-quality inductances are integrated together with the control unit, e.g. a MIPI-RFFE controller, in a single semiconductor device HLB. The MIPI controller can check all data that are important in mobile communication devices and it can control the components.

[0076] The MIPI controller can be realized in the baseband processor or in the RF chipset of the cellular phone.

[0077] A control unit can convert the digital MIPI-RFFE signal into specific control signals, e.g. in analog or digital form.

[0078] FIG. 6 shows an array of four tunable high-quality impedance elements, which are controlled by a common control unit CE. The arrangement can also have a greater number of tunable impedance elements IET. The tunable impedance elements IET have a tunable impedance. By way of example, they are embodied as tunable capacitances, which are tunable in terms of the capacitance value thereof. The information for tuning can be transmitted to the control unit CE by way of an MIPI-RFFE signal (MIPI), which control unit then undertakes appropriate tuning of the individual tunable capacitors CT or, precisely more generally, appropriate tuning of the impedance elements IET. The tunable impedance elements can be realized with different technologies. The entire arrangement can be realized in a semiconductor device. The control unit CE generates an actuation for the tunable capacitors from the MIPI signal.

[0079] Each one of the tunable impedance elements can be part of a tunable reactance element which in turn may constitute an interconnection of a tunable impedance element with one or more further passive components.

[0080] FIG. 7 shows an option of how a high-quality tunable capacitance can be embodied as an array of switchable capacitors. In order to set an arbitrary capacitance value, an arbitrary number of capacitors are interconnected with one another in parallel in an array. Possible settable, specific capacitance values emerge from various (partial) sums of the capacitances interconnectable in the array. Depicted in the figure is a capacitor C0. Parallel thereto, a first additional capacitor C1 can be switched in with the aid of a switch SW1. One or more additional capacitors C.sub.n can be interconnected in parallel with the capacitors C0 and C1 by way of switches SW.sub.n. By skillful selection of the capacitance values, it is thus possible to obtain very precise fine gradations of the resultant overall capacitance value. While the equivalent circuit for such a switchable capacitor array is depicted on the left, the symbol depicted on the right clarifies an arbitrary tunable capacitor, which can also be realized with a different technology, for example as a varactor.

[0081] There is a fundamental difference between switchable capacitors and directly tunable capacitors such as varactors, since the switchable capacitors can be switched digitally while a tunable capacitor such as a varactor is controlled by e.g. an analog signal which is applied to the varactor as a voltage and which is proportional to the achievable capacitance value.

[0082] FIG. 8 shows a further refinement of the invention, in which the coupling between adjacent devices is minimized for the discrete devices PD of the second component plane KE2 designed as high-quality inductances. This is achieved by virtue of directly adjacent inductances, which are e.g. embodied as SMD devices, being rotated by 90° with respect to one another in the second component plane. In the figure, a star denotes a virtual position in the device so that the direction of rotation can be read from the figure. It is possible to set a total of four different positions by carrying out, three times, a 90° rotation with in each case the same direction of rotation, and hence it is possible to obtain minimal coupling between the inductances.

[0083] In a further package (not depicted here), the passive components of the tunable filter are all arranged in the first component plane KE1 and, for example, realized as devices assembled on the substrate SU using a flip-chip construction. Here, different devices can be assembled, in which the passive components and the controller are realized separately from one another. The low-quality passive elements can be integrated into the substrate, but they can also be realized together with other components in a device in the first component plane. At least the low-quality passive components can be realized as an integrated passive device IPD.

[0084] The devices assembled using a flip-chip construction can also be provided with a passivation, a cover or a housing which, in principle, can be realized like in the aforementioned embodiments.

[0085] The invention is not restricted to the embodiments described in more detail in the exemplary embodiments, but only defined by the wording of the main claim. Individual new features in the claims, and sub-combinations thereof, are also considered to be in accordance with the invention.