JP4111344B2 - Front-end module for mobile communication equipment - Google Patents

Description

  The present invention relates to a front-end module mainly composed of a transmission / reception change-over switch that can be used for mobile communication devices such as mobile phones and automobile phones.

  As a front end module of a conventional mobile communication device, there is an antenna switch disclosed in Patent Document 1 proposed by the present applicant. Since most mobile phone systems are set to different frequency bands for transmission and reception, even if the transmission / reception switching unit and the antenna switching unit are similar circuits, the element constants are likely to be different, and the design can be done quickly. In the antenna switch described in Patent Document 1, the one switching unit and the other switching unit have a symmetric circuit configuration with a low-pass filter as a center so as not to be a burden in proceeding.

JP-A-9-261110

  The above-described conventional example is an antenna switch used for a TDMA type mobile phone, and cannot be applied to a device that handles two transmission / reception systems, such as a GSM dual band mobile phone in Europe. Therefore, there is a demand for a front-end module that mainly includes a transmission / reception changeover switch and includes a circuit that demultiplexes two bands. However, it is necessary to configure more circuit elements on the multilayer substrate of the front-end module. The board becomes complicated, and interference between circuits tends to occur. In particular, when the size is reduced, the interference between the circuits easily occurs.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a front-end module using a multilayer board that handles a plurality of transmission / reception systems and that is unlikely to cause interference between circuits even if it is downsized.

The front end module for a mobile communication device according to claim 1 is:
A multi-layer substrate having at least a demultiplexing circuit to which an antenna is connected, a transmission / reception switching switch connected to the antenna via the demultiplexing circuit and switched to the transmission circuit and the reception circuit, and a filter for removing high frequencies A front end module for mobile communication equipment used,
A dielectric layer for a branching circuit in which a capacitor electrode pattern constituting a branching circuit composed of two filters that respectively pass signals of different frequency bands is formed;
A ground electrode pattern opposed to the capacitor electrode pattern is formed on substantially the entire surface of the dielectric layer, and has a capacitor dielectric layer that mainly constitutes a capacitor other than the branching circuit,
The dielectric constant of the branching circuit dielectric layer is lower than the dielectric constant of the capacitor dielectric layer.

The front end module for a mobile communication device according to claim 2 is the method of claim 1,
The demultiplexing circuit dielectric layer includes a capacitor electrode pattern and a coil conductor pattern to form a demultiplexing circuit and a transmission / reception switching switch.

The front end module for a mobile communication device according to claim 3 is described in claim 1 or 2.
The ground electrode pattern is formed on the lower layer side of the multilayer substrate, and the dielectric layer made of the same material as the capacitor dielectric layer is formed on the upper layer side of the multilayer substrate. It is characterized by preventing deformation due to differences.

In the invention of claim 1, the relative dielectric constant of the dielectric layer constituting the diplexer, since the lower than the dielectric constant of the dielectric layer constituting the capacitor of the non-branching circuit, elements in the diplexer circuit Interference between them is reduced, and the high-frequency module can be easily downsized. In addition, it is easy to set the resonance frequency that requires accuracy.

  In the invention of claim 2, since the demultiplexing circuit and the transmission / reception switching switch are configured by forming the coil conductor pattern together with the capacitor electrode pattern in the demultiplexing circuit dielectric layer, the coil and the capacitor are separated from each other by a separate dielectric. The space on the dielectric layer can be used more effectively than in the case where it is formed in a layer, which can contribute to downsizing. In addition, since the dielectric layer for the branching circuit has a low relative dielectric constant, interference between capacitors and coils formed on the dielectric layer can be kept low.

  In the invention of claim 3, the ground electrode pattern is formed on the lower layer side of the multilayer substrate, and the dielectric layer made of the same material as the capacitor dielectric layer is formed on the upper layer side of the multilayer substrate. Deformation due to the difference in shrinkage due to firing can be prevented.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a front end module. The front end module 1 has surface mount components 11 and 12 mounted on the multilayer substrate 20, and a shield case 15 is fixed to the multilayer substrate 20 so as to cover the multilayer substrate 20 and the surface mount components 11 and 12. ing.

  The multilayer substrate 20 includes dielectric layers 21 to 36. In FIG. 1, each of the dielectric layers 21 to 36 is drawn with a thickness corresponding to the actual thickness.

  FIG. 2 shows the layer structure of the front end module. The front end module is made by laminating dielectric green sheets formed by arranging the electrodes, connection patterns, via holes or marks for the front end module vertically and horizontally, cutting into individual front end modules, and thermocompression bonding. The individual multilayer substrate 20 shown in FIG. 1 is manufactured by firing.

  In FIG. 2, reference numerals 21 to 36 denote the dielectric layers shown in FIG. These dielectric layers 21 to 36 are dielectric green sheets in the manufacturing process. Arrows a to o mean that they are stacked. In the laminating step, the green sheet 21 that is a dielectric layer is the lowermost layer, the green sheet 35 that is a dielectric layer is overlaid thereon, and the green sheet 34 is further overlaid thereon. ~ 36 are stacked. In the firing process after thermocompression bonding and cutting of these green sheets, they are integrated as a sintered body, the dimensions change according to the shrinkage ratio associated with firing, and a dielectric layer having predetermined electrical characteristics is obtained by firing. .

FIG. 3 is a circuit diagram showing an example of the circuit configuration of the front end module 1. In FIG. 3, T1 to T12 are external connection electrodes. Among these external connection electrodes, T9 is an antenna external connection electrode, and the coils L1, L2, and L11 and the capacitors C1, C11, and C12 constitute a branching circuit. The circuit (the circuit on the right side in the drawing) from the coil L1 and the capacitor C1 to the external connection electrode T11 is a circuit corresponding to the DCS system (1.8 GHz band). A circuit (a circuit on the left side in the drawing) from the coil L11 and the capacitor C11 to the transmission circuit external connection electrode T1 corresponds to the GSM system (900 MHz band). Therefore, the capacitors C11 and C12 and the coil L11, which are part of the branching circuit, allow the low-frequency side signal (signal used in the GSM system) to pass through and the high-frequency side signal (signal used in the DCS system) to be cut off. Configure. Further, the capacitor C1 and the coils L1 and L2, which constitute the remainder of the branching circuit, allow the high-frequency side signal (signal used in the DCS system) to pass through and the low-frequency side signal (signal used in the GSM system) to be cut off. Configure.

  In the circuit corresponding to the DCS system on the right side, T11 is a transmission circuit external connection electrode connected to the DCS system transmission circuit. T7 is a receiving circuit external connection electrode connected to a DCS receiving circuit. T8 is a grounding external connection electrode grounded by an external circuit. T10 is a control signal external connection electrode for adding a control signal for DCS transmission / reception switching. The coil L6 and the capacitors C6 to C8 constitute a low pass filter. Diodes D1 and D2, coils L3 to L5, and capacitors C2 to C5 and C9 constitute a transmission / reception changeover switch.

  In the circuit corresponding to the GSM system on the left side, T1 is a transmission circuit external connection electrode connected to the GSM system transmission circuit. T5 is a receiving circuit external connection electrode connected to the GSM receiving circuit. T2 is a control signal external connection electrode for applying a control signal for performing GSM transmission / reception switching. T4 is a grounding external connection electrode grounded by an external circuit. The coil L14 and the capacitors C17 to C19 constitute a low pass filter. The diodes D11 and D12, the coils L12 and L13, and the capacitors C13 to C16 constitute a transmission / reception changeover switch. T3, T6, and T12 are ground external connection electrodes that are connected to the ground electrode inside the front end module and also connected to the ground portion of the external circuit.

  4 to 6 show the appearance of the front end module 1. 4 is a front view seen from the same direction as FIG. 1, FIG. 5 is a plan view, and FIG. 6 is a side view seen from a direction orthogonal to FIG. As shown in FIG. 4 and FIG. 6, the left and right ends (on the drawing) of the shield case 15 are bent downward so as to be orthogonal to the plane portion, and the bent ends 15A and 15B are grounded as ground electrodes, respectively. The external connection electrodes T6 and T12 are fixedly connected. In FIG. 4, the surface mount components 11 and 12 are not shown.

  In FIG. 5, 15 </ b> C is a hole provided in the shield case 15, which is a mark indicating the direction of the front end module 1. As shown in FIG. 5, external connection electrodes T1 to T12 for connecting the circuit of the front end module to the outside are disposed on the outer periphery of the front end module. These external connection electrodes T1 to T12 are used to connect a front end module mounted on a circuit board of a mobile phone.

  The front end module of this example has a height including the shield case 15 of 1.8 mm, a horizontal width in FIG. 5 of 6.5 mm, and a vertical width of 4.8 mm.

  Next, the structure of the front end module will be described in more detail. As shown in FIGS. 1 and 2, a ground electrode pattern 201 is formed on almost the entire surface of the lower dielectric layer 35, and a counter electrode pattern 202 of the ground capacitor is formed on the dielectric layer 34 adjacent to the upper side thereof. Is done. In addition to the counter electrode pattern 202, a plurality of counter electrode patterns are formed on the dielectric layer 34, but the reference numerals are omitted. On the dielectric layer 33 adjacent to the dielectric layer 34, a ground electrode pattern 203 and other electrode patterns shown without reference numerals are formed.

  Dielectric layers 28 to 32 having almost no pattern are stacked on the ground capacitor. These dielectric layers 28 to 32 include a via hole 204 for connecting patterns between upper and lower adjacent dielectric layers, a connection pattern 205 for connecting the via holes, an electrode pattern 206, and other electrodes in which signs are omitted. Some of the capacitor electrode patterns for the pattern and branching circuit are formed.

  Further, dielectric layers 22 to 27 are stacked on the upper side. A coil and a capacitor are formed by patterning these dielectric layers 22 to 27 by mixing a coil conductor pattern and a capacitor electrode pattern.

  Electrode patterns 211 to 218 are capacitor electrode patterns for a branching circuit. The demultiplexing circuit capacitor electrode patterns 211 to 218 are formed so as to be positioned in the middle in the vertical direction (that is, in the middle on the plane) in each of the dielectric layers 22 to 29 in FIG. As described above, the capacitor electrode patterns 211 to 218 are formed at the same position on the plane and overlapped in the stacking direction, so that the capacitor electrode pattern of the capacitor constituted by the ground electrode patterns 201 and 203 and the capacitor electrode pattern 202 is obtained. Interference with the branching circuit capacitor configured by 211 to 218 is reduced.

  Then, on each dielectric layer 22 to 26, a circuit corresponding to the DCS system is formed on the upper side and a circuit corresponding to the GSM system is formed on the lower side in each dielectric layer of FIG. .

  That is, a connection pattern 221 for the DCS system is formed on the dielectric layer 27 on the upper side in the drawing, and a coil pattern for the DCS system is formed on the upper side in the drawing of each layer on the dielectric layers 22 to 26. Conductive patterns 222 to 226 are formed.

  On the other hand, on the dielectric layer 27, a connection pattern 231 for the GSM system is formed on the lower side in the drawing, and the dielectric layers 22 to 26 are formed on the lower side in the drawing of each layer for the GSM system. The coil conductor patterns 232 to 236 are formed.

  Since the module is used in a high frequency band such as the GSM system and the DCS system, the patterns forming the respective elements must be arranged with sufficient consideration for mutual interference. In particular, since the band of the DCS system has a frequency approximately twice that of the GSM system, it is necessary to consider the influence on the second harmonic of the GSM transmission system. However, in the configuration shown in FIG. 2, the circuit corresponding to the DCS system and the circuit corresponding to the GSM system are almost symmetrical with respect to the branching circuit capacitor electrode patterns 211 to 218 shared by both circuits. That is, the areas are arranged separately, and there is an effect that the entire circuit is miniaturized while separating both circuits by the capacitor electrode patterns 211 to 218 for the demultiplexing circuit.

  A connection pattern 219 is formed on the dielectric layer 21. The surface mount components 11 and 12 are connected to and mounted on the connection pattern 219. The surface mount components 11 and 12 are diodes, chip resistors, chip capacitors, or chip inductors, and are appropriately arranged according to the circuit configuration.

  The connection pattern 219 is connected to a corresponding via hole according to a circuit configuration. Of the external connection electrodes T1 to T12, for example, the control signal external connection electrodes T8 and T4 are connected to connection patterns 221 and 231 that are lead patterns of the internal electrodes.

  In the present embodiment, the arrangement of the dielectric layers 21 to 36 shown in FIGS. 1 and 2 is determined in consideration of the electrical characteristics and the reduction ratio accompanying the firing of the green sheet. That is, the uppermost dielectric layer 21 has a relative dielectric constant of about 11, and a green sheet with a small reduction ratio is selected. In addition, the dielectric layers 22 to 32 thereunder are selected to be green sheets having a relative dielectric constant of about 7.3 and a slightly large reduction ratio. In addition, the dielectric layers 33 and 34 below the same are selected as green sheets having a relative dielectric constant of about 11 and a low shrinkage ratio, similar to the uppermost dielectric layer 21. Further, the dielectric layers 35 and 36 underneath are selected to have a relative dielectric constant of about 7.3 and a slightly larger shrinkage ratio, similar to the dielectric layers 22 to 32.

  That is, the dielectric layers 22 to 26 mainly form a conductor pattern for a coil, and the dielectric layers 27 to 32 mainly form a connection pattern, and any of the dielectric layers 22 to 32 has a relative dielectric constant of 7. Select a material that will be about 3. Since these dielectric layers 22 to 32 have a low relative dielectric constant, interference due to stray capacitance with adjacent patterns can be prevented. The dielectric layers 33 and 34 are dielectric layers between the electrodes constituting the capacitor, and both of them select a material having a relative dielectric constant of about 11. Thus, by making the relative dielectric constant higher than that of other dielectric layers, it is easy to obtain the capacitance as a capacitor. However, the dielectric layers 33 and 34 have a small shrinkage ratio due to firing, while the upper dielectric layers 22 to 32 have a large shrinkage ratio and are deformed during firing. Therefore, by selecting a material having the same low shrinkage ratio as that of the dielectric layers 33 and 34 for the uppermost dielectric layer 21, deformation during firing is prevented.

  In addition, the transmission / reception changeover switch is composed of a diode and an LC circuit, and the LC circuit part is formed in a multilayer substrate. Since it is not necessary to consider the impedance matching of the stripline, it is not necessary to provide a dielectric layer for matching the stripline, so that the multilayer substrate can be made thinner.

  In addition, since the coil conductor patterns 221 to 226 and 231 to 236 are formed on the dielectric layer constituting the demultiplexing circuit together with the capacitor electrode patterns 211 to 218, the demultiplexing circuit and the transmission / reception switching switch are configured. Compared with the case where the layers are formed on separate dielectric layers, the space on the dielectric layer is effectively utilized, which contributes to downsizing.

  Next, the arrangement of the external connection electrodes T1 to T12 will be described with reference to FIGS. In FIG. 5, when the line connecting the grounding external connection electrodes T6 and T12 is a center line 50, one outer peripheral portion (on the lower side in the drawing) parallel to the center line is connected to the GSM system. Electrodes T1 to T5 are provided. In addition, DCS type external connection electrodes T7 to T11 (however, the antenna external connection electrode T9 is common to both types) are provided on the other outer peripheral portion (upper side in the drawing).

  Thus, the external connection electrodes T6 and T12 are provided between the external connection electrode rows of the different communication systems so that the external connection electrodes are opposite to each other on the module (multilayer board) by different communication systems. Therefore, interference between the external connection electrodes T1 to T5 of different systems and T7, T8, T10, and T11 is reduced, and as described above, a circuit for each communication system provided in the multilayer substrate is also provided. A front-end module that can be easily formed by being divided into areas and in which interference between circuits is reduced even when miniaturized can be realized.

  In this embodiment, the external connection electrodes adjacent to the transmission circuit external connection electrodes T1 and T11, the reception circuit external connection electrodes T5 and T7, and the antenna external connection electrode T9 are connected to the control signal external connection. By using the electrodes T2, T4, T8, T10 or the ground external connection electrodes T6, T12, the transmission circuit external connection electrodes T1, T11, the reception circuit external connection electrodes T5, T7 and the antenna external connection electrode T9 The external connection electrodes are not adjacent to each other.

  By arranging such external connection electrodes, interference between the transmission circuit external connection electrodes T1, T11, the reception circuit external connection electrodes T5, T7 and the antenna external connection electrode T9 is reduced, and the front end module Even if the size is reduced, a better effect can be obtained in preventing interference.

Sectional drawing which shows one Embodiment of the front end module of this invention. The figure which shows the pattern formed in each dielectric material layer of the multilayer substrate of this embodiment. The circuit diagram which shows an example of the circuit structure of the front end module of this embodiment. The front view which shows the external appearance of the front end module of this embodiment in the same direction as FIG. It is a top view of the front end module of the embodiment. The side view of the front end module of this embodiment.

Explanation of symbols

1: front end module, 11, 12: surface mount component, 15: shield case, 20: multilayer substrate, 21-36: dielectric layer, 50: center line, 201, 203: ground electrode pattern, 202: counter electrode, 204: Via hole, 205, 219, 221, 231: Connection pattern, 206: Electrode, 211-218: Capacitor electrode pattern for branching circuit, 222-226, 232-236: Conductor pattern for coil, T1-T12: External connection electrode

Claims (3)

A multi-layer substrate having at least a demultiplexing circuit to which an antenna is connected, a transmission / reception switching switch connected to the antenna via the demultiplexing circuit and switched to the transmission circuit and the reception circuit, and a filter for removing high frequencies A front end module for mobile communication equipment used,
A dielectric layer for a branching circuit in which a capacitor electrode pattern constituting a branching circuit composed of two filters that respectively pass signals of different frequency bands is formed;
A ground electrode pattern opposed to the capacitor electrode pattern is formed on substantially the entire surface of the dielectric layer, and has a capacitor dielectric layer that mainly constitutes a capacitor other than the branching circuit,
A front end module for a mobile communication device, wherein a dielectric constant of the dielectric layer for branching circuit is lower than a dielectric constant of the dielectric layer for capacitor. In the front end module for mobile communication devices according to claim 1,
A front end module for a mobile communication device, wherein a coil conductor pattern is formed together with a capacitor electrode pattern in the dielectric layer for a branching circuit to constitute a branching circuit and a transmission / reception switching switch. The front end module for a mobile communication device according to claim 1 or 2,
The ground electrode pattern is formed on the lower layer side of the multilayer substrate, and the dielectric layer made of the same material as the capacitor dielectric layer is formed on the upper layer side of the multilayer substrate. A front-end module for mobile communication equipment characterized by preventing deformation due to differences.

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