This patent application describes an electrical multiband component.
A multiband component with a triplexer is known from US 2003/0124984.
A multiband component with a triplexer and a bandpass surface acoustic wave filter in a GPS path is known from US 2004/0116098.
Described herein is an electrical multiband component with which largely interference-free reception is possible in a given frequency band, even during data communication in other frequency bands.
An electrical multiband component is described that comprises at least three signal paths, each for the transmission of signals in a frequency band of its own. The component comprises a diplexer, to which an antenna path is connected on the input side and the signal paths are connected at the output. A bandpass filter, comprising a double mode SAW filter (resonator filter with acoustically coupled transducers), is arranged in at least one of the signal paths.
A DMS filter is a resonator filter with acoustically coupled transducers operating with surface acoustic waves. The DMS filter comprises at least one acoustic track that is delimited by two reflectors and comprises a transducer arrangement with at least three transducers.
The multiband component is characterized by low insertion loss in passbands of the signal paths. The signal path with the DMS filter arranged therein has high isolation—in one embodiment more than −40 dB—from other signal paths.
The DMS filter may be implemented as a SAW chip. In an embodiment, the multiband component comprises a carrier substrate on which the SAW chip is located.
The carrier substrate comprises metallization planes and dielectric layers arranged between them, which may be made from ceramic(s) or a laminate.
Additional elements of the component, e.g., low-pass filters, diplexers or matching networks for matching the output impedance of signal paths, can be integrated in the carrier substrate or mounted on the upper side of the substrate. In particular, the above-mentioned antenna-side diplexer can be integrated into the carrier substrate, at least in part. Integration into the substrate means that circuit elements are designed as conductor tracks in at least one of the metallization planes of the carrier substrate.
The first and second signal may be each a transmit/receive path. The third signal path may be a receive path.
The first signal path may be used for a frequency band with a center frequency of approximately 1 GHz or 900 MHz. The second signal path may be used for a frequency band with a center frequency starting from approximately 1800 MHz.
The multiband component may be used for the separation of different mobile radio paths and for the transmission of data in an additional frequency band. In an embodiment, the first and second frequency bands are mobile radio bands and the third frequency band is a GPS band.
For the center frequency f1 of the first frequency band, the center frequency f2 of the second frequency band and the center frequency f3 of the third frequency band, f1<f3<f2. In one embodiment: f3≧2f1 and/or f3<f2<1.5f3.
The first frequency band can be, for instance, an AMPS band for a CDMA transmission method (AMPS=Advanced Mobile Phone system, CDMA=Code Division Multiple Access). This corresponds to a frequency band of 824-894 MHz with a center frequency f1 of 859 MHz. The first signal path is assigned to the first frequency band.
The third frequency band may be assigned to GPS signals. GPS stands for Global Positioning System, with a frequency band of 1574.42-1576.42 MHz and a center frequency f3 of 1575.42 MHz. The third signal path is assigned to the third frequency band.
The second frequency band is assigned, e.g., to a PCS band (PCS=Personal Communication System) of 1850-1990 MHz with a center frequency f2 of 1920 MHz. The second signal path is assigned to the second frequency band.
The specified multiband component is not limited, however, to a tri-band design. Additional signal or data communication paths, such as a transmit path for UMTS and/or Bluetooth data can also be provided.
The frequency-separating filter may be constructed exclusively from passive circuit elements such as capacitors and inductors. This has the advantage of low power consumption in a terminal device. At least part of the components, or all the components, of the frequency-separating filter can be integrated into the carrier substrate. It is also possible for at least one component of the frequency-separating filter to be formed as a chip mounted on this substrate.
The chips can have surface-mountable contacts (SMD contacts). The chips can also be constructed as bare-dies, which are electrically connected by bond wires to the carrier substrate. The chips, in particular the SAW chip, can alternatively be mounted on the carrier substrate in a flip-chip arrangement.
It is additionally assumed that the bandpass filter is arranged in the third signal path.
The frequency-separating filter may have a multi-level construction. The frequency-separating filter comprises a first diplexer and a second diplexer in one embodiment. The second and third signal paths are combined into a common path by the second diplexer. The common path and the first signal path are combined into the antenna path by the first diplexer.
The first diplexer comprises a first low-pass filter that may be connected to the first signal path, and a first high-pass filter that may be connected to the common path. The second diplexer comprises a second low-pass filter that may be connected to the third signal path and a second high-pass filter that may be connected to the second signal path.
The bandpass filter can have a stopband, i.e., a particularly high suppression of signals, in the first or second frequency range.
The second high-pass filter can have a transfer function that has a pole at a frequency essentially in the first or the third frequency band.
The double mode SAW filter can comprise one or more acoustic tracks, each with an arrangement of several transducers in a row. Several input transducers may be connected in parallel. Several output transducers connected in parallel are provided. The transducer arrangement comprises at least five transducers in one embodiment, wherein input and output transducers of the respective acoustic track may be arranged alternately. In one embodiment, one input transducer is arranged between every two output transducers. In another embodiment, one output transducer is arranged between two input transducers.
The bandpass filter can further comprise at least one SAW resonator, upstream or downstream of the double mode SAW filter. It is also possible to connect one resonator on the input side and another resonator on the output side. The SAW resonator comprises, for example, a transducer that is arranged between two reflectors.
The SAW resonator can be a series or a parallel resonator. A series resonator is inserted into the signal path and a parallel resonator into a shunt arm between the signal path and ground.
The at least one SAW resonator specified here can also be replaced by at least one ladder-type element or a ladder-type arrangement of SAW resonators, which comprises at least one series resonator and at least one parallel resonator.
The bandpass filter can have a symmetrical output in one embodiment. The DMS filter can be advantageously used as a balun.
A third low-pass filter that suppresses signals of the second and the third frequency bands can be arranged in the first signal path. Its transfer function can have a pole at a frequency lying essentially in the second or third frequency band.
A matching network for matching the output impedance of the second signal path for the predetermined second frequency band can be arranged on the output side of the second high-pass filter. A matching network for matching the output impedance of the third signal path for the predetermined third frequency band can also be arranged on the output side of the bandpass filter.
At least one of the signal paths can be separated by a duplexer or a changeover switch into a receive branch and a transmit branch. The duplexers and the changeover switches may be located on the carrier substrate.
In an advantageous embodiment the frequency-separating filter comprises a bandpass filter with a DMS track arranged in the third signal path and a diplexer for separating signals of the first and the second frequency bands. In this case, the bandpass filter is directly connected to the common antenna path, i.e., without an upstream diplexer. The frequency-separating filter is considered a triplexer in this case.
The multiband component can be realized as a compact, e.g., SMD-mountable chip, which is also referred to below as a front-end module. This chip can comprise the following elements (in each signal path if appropriate) in one component in particular: 1) a duplexer, 2) a power amplifier, a power detector, a directional coupler, at least one changeover switch, e.g., for controlling the amplifier, in the transmission branch of the signal path. The integration of a bandpass filter at the input of the power amplifier is provided. Apart from the above-mentioned components of a transmit path, components of at least one receive path, such as an LNA and/or a bandpass filter, can also be realized in the same module.
The multiband component and advantageous configurations thereof will be described below on the basis of schematic figures not true to scale.
Frequency-separating filter 40 comprises diplexers connected in series. Frequency-separating filter 40 comprises a first diplexer 41 connected to the antenna for separating signals of the first frequency band, which are conducted into first signal path 1, from the signals of the second and third frequency bands, which are conducted into a common path 23 for these bands.
A second diplexer 42 is arranged in common path 23. Second diplexer 42 is provided for separating signals of the second frequency band, which are conducted into second signal path 2, from the signals of the third frequency band, which are conducted into third signal path 3.
First diplexer 41 comprises a low-pass filter 11 arranged in the first signal path as well as a high-pass filter 230 arranged in common path 23. Second diplexer 42 comprises a low-pass filter 31 arranged in the third signal path as well as a high-pass filter 21 arranged in second path 2.
In first signal path 1 (e.g., cell), an additional low-pass filter 12 is arranged downstream of low-pass filter 11. In second signal path 2 (e.g., IMT=International Mobile Telecommunications, or PCS), a matching network 22 for matching the output impedance of second output port OUT2 to a reference impedance, e.g., 50Ω, is arranged downstream of high-pass filter 21. Matching network 22 can be integrated into the carrier substrate or be present as a chip mounted on the substrate.
In third signal path 3 (e.g., GPS), a bandpass filter 32 that comprises a DMS filter according to
It is also possible to arrange a matching network for matching the output impedance of first output port OUT1 on the output side in first signal path 1, i.e., downstream of low-pass filter 12.
The multiband component can comprise components not shown in detail here, in addition to the diplexers, filters and matching networks shown in
In an additional embodiment, it is possible to realize inductors L1 and L3 in at least one metallization plane of carrier substrate 90 as structured, e.g., meander-shaped, folded or spiral conductor tracks. Parts of an inductor can be arranged in different metallization planes and be connected to one another by vertical plated through-holes.
The dielectric layers of the carrier substrate may be made from a ceramic material, e.g., LTCC (LTCC=Low-Temperature Cofired Ceramics). Plastic, e.g., with a high dielectric constant ε>10, is also possible as material for these layers.
The use of a multi-layer substrate as carrier substrate and a surface-mountable SAW chip with the DMS filter has the advantage that a compact element with a small surface area and low insertion loss in passbands of the signal paths can be realized in this manner.
An example of an implementation of the circuit according to
Low-pass filter 12 is realized as a capacitor C2 connected to ground in a shunt arm, and a parallel resonant circuit, consisting of an inductor L2 and a capacitor C3, in signal path 1. The low-pass filter 12 selects all signals with a frequency in the first frequency band or below it, and attenuates signals at higher frequencies, in particular, signals from the second and third frequency bands.
High-pass filter 21 comprises a capacitor C4 arranged in signal path 2, and a series resonant circuit, comprised of an inductor L3 and a capacitor C5, connected in a shunt arm to ground. Series resonant circuit L3, C5 may be tuned in such a way that it has its resonant frequency in the third frequency band and thus attenuates the signals of the third band with high suppression. Inductor L3 may have a high Q factor, which can be obtained, e.g., with a chip inductor with SMD contacts.
Low-pass filter 31 comprises a capacitor C6 connected to ground, and an inductor L4 arranged in signal path 3. The low-pass filter 31 transmits signals of the third band and blocks frequencies above the third band. Together with bandpass filter 32, it is possible to select the signals of the third band and attenuate the signals of the first and second bands.
A matching network 33, comprising a series inductor L5 and a capacitor C7 in the shunt arm, which together form a low-pass filter, is inserted downstream of bandpass filter 32. The output impedance at output port OUT3 is matched by matching network 33 to 50Ω, for example, or to some other reference impedance.
Matching network 22 comprises a series inductor L6, which is a part of the multiband component in one embodiment. This inductor can also be arranged externally, i.e., on a printed-circuit board on which the element is mounted. This inductor can also be realized in the carrier substrate. In one embodiment, inductor L6 can serve, for instance, to adapt the output impedance at second output port OUT2 in such a manner that the second signal path 2 can be used for transmission of higher-frequency signals, e.g., signals of the S-DMB-frequency band 2633-2650 MHz (S-DMB=Satellite Digital Multimedia Broadcast). In an embodiment, the second signal path, like the third signal path, can be a pure receive path.
Matching networks 22, 33 can each have circuit components other than inductors L6, L5 and capacitor C7.
The parallel resonance of parallel resonator L2, C3 may be such that this resonant circuit blocks in the second or third frequency band. Thus, a pole or a stopband with a high signal suppression is produced in the transfer function of the first signal path.
The series resonance of the series resonator L3, C5 may be in the first or third frequency band. The signals of this frequency band are short-circuited to ground. A zero or a stopband with high signal suppression is thus produced in the transfer function of the second signal path.
Transducers 504, 504 can also be used as output transducers, in which case transducers 501, 503 and 505 are used as input transducers.
The DMS track can comprise only three transducers or more than only five transducers in one embodiment. The input and output transducers are always alternately arranged in a row in the wave propagation direction. The DMS track may be formed mirror-symmetrically or point-symmetrically relative to its center axis or center point.
At least one transducer, such as a centrally arranged transducer, can have a V-split.
One SAW resonator 60 is connected on the input side of DMS track 50 and another SAW resonator 79 on the output side. Resonator 60 comprises reflectors 62 and a transducer 61 arranged between reflectors 62. Resonator 70 comprises reflectors 72 and a transducer 71 is arranged between reflectors 72.
In one embodiment, at least one of the resonators 60, 70 shown in
The use of a DMS track in bandpass filter 32 of third signal path 3 has the advantage that thereby a high isolation—in one embodiment at least −40 dB—of the entire second or third frequency band from the other two frequency bands (i.e., first and the second frequency band) can be ensured.
In the embodiment shown in
The transfer functions of the multiband component are shown in
Transfer function 82 of the second signal paths exhibits low insertion loss in the frequency range of 1.6 to 3 GHz.
Transfer function 83 of the third signal path has a high suppression of signals in an upper stopband above 1.7 GHz as well as a very high suppression of signals below 1.3 GHz. At the same time low insertion loss in the third frequency band can be obtained in the transfer function of the third signal paths 3.
In one embodiment, additional, e.g., passive components such as duplexers for separating transmit and receive signals of the respective signal paths, can be arranged on or in the carrier substrate. The arrangement of semiconductor chips, e.g., changeover switches, on the substrate can also be contemplated.
An embodiment of the front-end module which comprises the below-specified components of first signal path 1 is shown in
Third signal path 3 in
Diplexer 41 is provided as in
An embodiment of the front-end module, which comprises the below-specified components of the two signal paths 1 and 2 is shown in
Second signal path 2 is constructed essentially the same as first signal path 1 already described in
Transmit path TX1 in
Ven is a supply voltage for supplying the power detector. Vdet is an output voltage that serves to detect or monitor the signal strength of the amplifier output signal and corresponds to a rectified component of the transmit signal.
Voltages Vcc, Vcc1 and Vcc2 are supply voltages for the respective amplifier. Vreg is a reference voltage for the amplifier. Vstby is a control voltage for controlling a changeover switch 481, 482, which is actuated to release reference voltage Vreg or set in standby mode. The amplifier does not consume power in standby mode. Vmode is a voltage that serves to select and set the operating mode of the amplifier.
In one embodiment, it is possible to integrate components, not shown, of receive paths RX1, RX2 such as a bandpass filter and a low-noise amplifier (LNA) into the specified front-end module.
It is advantageous to realize passive module components such as diplexers, low-pass filters, lines, directional couplers, inductors and capacitors inside the carrier substrate and to realize bandpass filters, duplexers and active components as chips on the carrier substrate.
The components arranged on the carrier substrate, particularly the bandpass filter with the DMS track, can each be constructed as an unpackaged chip (bare-die) or as a housed chip (e.g., an SMD component). A bare-die can be wire-bonded to the carrier substrate or mounted in a flip-chip arrangement.
Duplexers 431, 432 in the embodiments presented in
A duplexer usually comprises a transmit filter, a receive filter and a matching network for impedance matching, comprising, for example, a phase line, such as a λ/4-line, arranged in the receive branch.
It is possible to realize the transmit filter and the receive filter of a duplexer in a common duplexer chip. It is alternatively possible to construct these filters as separate filter chips. The matching network of the duplexer can be integrated, at least in part, into the duplexer chip or filter chip. The λ/4-line may be completely integrated into the duplexer chip. In addition, the matching network of the duplexer can be integrated, at least in part, into the substrate.
The specified multiband component, in particular, the arrangement of matching networks, filters and diplexers, is not limited to the arrangements shown in figures. If appropriate, the diplexer can be constructed in an embodiment as a triplexer, although the arrangement with cascaded diplexers appears particularly advantageous.
Number | Date | Country | Kind |
---|---|---|---|
102005020086.9 | Apr 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP06/03824 | 4/25/2006 | WO | 00 | 10/26/2007 |