Patent Application
20050037804
This application claims priority to Japanese Patent Application No. 2003-192288 filed Jul. 4, 2003 which is hereby expressly incorporated by reference herein in its entirety.
1. Technical Field
The present invention relates to a high-frequency module fabricated by modularizing respective circuit elements forming a high-frequency portion, such as a wireless communications device, in a multi-layer substrate.
2. Related Art
Wirelessly networked information devices (wireless LANs) are being used in homes and offices. The currently most popular wireless LAN uses a 2.4 GHz band as its frequency.
A wireless LAN using the 2.4 GHz band, however, may not be able to handle the expected increased volume of communications, because the usable frequency band is too narrow. Accordingly, standards for a wireless LAN system using a 5 GHz band have been newly established.
Under these circumstances, a wireless LAN using the 2.4 GHz band and the 5 GHz band may have to be used by a single (common) communications apparatus. An apparatus shown in
As shown in
To be more specific, a demultiplexer circuit 4, commonly used by the reception portion 1 and the transmission portion 2, is provided between the transmission/reception antenna 3 and the switching switches 5 and 6. The reception portion 1 includes low-noise amplifier circuits 7 and 8, a high-frequency amplifier circuit 9, a mixer circuit (mixer) 10, a filter circuit 11, and an intermediate amplifier circuit 12. The transmission portion 2 includes a filter circuit 15, a mixer circuit 16, a high-frequency amplifier circuit 17, driver circuits 18 and 19, and power amplifier circuits 20 and 21. A synthesizer circuit 13 and a digital signal processing circuit 14 are used commonly by the reception portion 1 and the transmission portion 2.
In the communications apparatus configured as described above, for example, the demultiplexer circuit 4, the switching switches 5 and 6, the power amplifier circuits 20 and 21, etc., all enclosed in a broken line of
Incidentally, assuming that the high-frequency module 22 used in the conventional communications apparatus described above is adapted to a wireless LAN using the 2.4 GHz band and the 5 GHz band, then two transmission/reception switching switches are used for each frequency band.
However, because the usable frequencies in the wireless LAN are in the 2.4 GHz band and the 5 GHz band, which are quite high, there is a problem that when the switching switches are used, insertion of the switching switches accompanies a considerable power loss.
In order to eliminate this problem and secure communications quality, the transmission portion needs to increase the output power of the power amplifier circuits, whereas the reception portion needs to apply low-noise amplification to reception signals with the use of the low-noise amplifier circuits.
Also, because the switching switches cannot be formed inside the multi-layer substrate, they have to be mounted on the top surface of the multi-layer substrate. Moreover, two switching switches have to be mounted. Hence, the high-frequency module has a problem that not only the area, but also the size of the multi-layer substrate is increased.
In addition, in a wireless LAN using the 2.4 GHz band and the 5 GHz band, the usable frequencies are high and there is a two-fold or more difference. It is thus necessary to use expensive elements, such as gallium arsenide, in order to achieve switching switches using a semiconductor.
On the other hand, a wireless LAN using the 2.4 GHz band and the 5 GHz band has the following properties: the antenna can be extremely small due to significantly high usable frequencies; there is a two-fold or more difference between the usable frequencies; and transmission power is small.
In view of the foregoing, the advent of a novel high-frequency module having no transmission/reception switching switches is expected for a wireless LAN using the 2.4 GHz band and the 5 GHz band.
The invention therefore has an object to provide a high-frequency module that obviates transmission/reception switching switches, so that in addition to preventing a power loss associated with the switching switches, the module can also be reduced in size.
In order to solve the above problems and thereby achieve the above and other objects, the invention is configured as follows.
That is, a first aspect of the invention provides a high-frequency module, which includes: a reception portion that processes a reception signal received by a reception antenna; and a transmission portion that processes a transmission signal to be supplied to a transmission antenna, and is configured in such a manner that: the reception portion includes a first demultiplexer circuit that divides the reception signal among plural reception lines having different frequency bands from each other; the transmission portion includes plural power amplifier circuits that respectively amplify transmission signal power in different frequency bands, and a second demultiplexer circuit that supplies the outputs of the power amplifier circuits to the transmission antenna; and the first demultiplexer circuit included in the reception portion, and the power amplifier circuits and the second demultiplexer circuit included in the transmission portion are provided in a multi-layer substrate.
According to this configuration, the transmission/reception switching switches can be omitted. Hence, not only can a power loss associated with the switching switches be prevented, but also the module can be reduced in size at a lower cost.
A second aspect of the invention provides the high-frequency module according to the first aspect, configured in such a manner that: the transmission portion further includes a directional coupling circuit, provided between the power amplifier circuits and the second demultiplexer circuit, to extract part of the outputs of the power amplifier circuits; and the directional coupling circuit is provided in the multi-layer substrate.
According to the above configuration, output power can be monitored.
A third aspect of the invention provides the high-frequency module according to the first or second aspect, configured in such a manner that the reception portion includes plural first demultiplexer circuits, and each of the first demultiplexer circuits demultiplexes the reception.
According to the above configuration, the high-frequency module can be adapted to a communications apparatus of a diversity reception system.
A fourth aspect of the invention provides the high-frequency module according to any of the first through third aspects, configured in such a manner that: the reception portion further includes the reception antenna; and the reception antenna is provided in the multi-layer substrate.
According to the above configuration, a connector that connects the reception antenna to the first demultiplexer circuit can be omitted.
A fifth aspect of the invention provides the high-frequency module according to any of the first through fourth aspects, configured in such a manner that: the transmission portion further includes the transmission antenna; and the transmission antenna is provided in the multi-layer substrate.
According to the above configuration, a connector that connects the transmission antenna and the second demultiplexer circuit can be omitted.
A sixth aspect of the invention provides the high-frequency module according to any of the first through fifth aspects, configured in such a manner that: the reception portion further includes low-noise amplifier circuits, provided to a latter stage of the first demultiplexer circuit, to respectively amplify the reception signals demultiplexed in the first demultiplexer circuit; and the low-noise amplifier circuits are provided in the multi-layer substrate.
According to the above configuration, a subtle reception signal can be received and processed.
A seventh aspect of the invention provides the high-frequency module according to any of the first through fifth aspects, configured in such a manner that: the reception portion further includes unbalanced-to-balanced transformer circuits, provided to a latter stage of the first demultiplexer circuit, to respectively transform unbalanced reception signals demultiplexed in the first demultiplexer circuit to balanced signals; and the unbalanced-to-balanced transformer circuits are provided in the multi-layer substrate.
According to the above configuration, a balanced signal can be outputted to the outside.
An eighth aspect of the invention provides the high-frequency module according to any of the first through seventh aspects, configured in such a manner that: the transmission portion further includes balanced-to-unbalanced transformer circuits, provided to a preceding stage of the power amplifier circuits, to transform inputted balanced signals to unbalanced signals; and the balanced-to-unbalanced transformer circuits are provided in the multi-layer substrate.
According to the above configuration, a balanced signal can be received from the outside and amplified.
A ninth aspect of the invention provides the high-frequency module according to any of the first through eighth aspects, configured in such a manner that the multi-layer substrate comprises a low-temperature co-fired ceramics substrate.
FIGS. 2(A)-(D) are views used to schematically describe an example of the structure of the first embodiment,
Embodiments of the invention will now be described with reference to the accompanying drawings.
A high-frequency module 30 of the first embodiment is adapted, for example, to a wireless communications apparatus for a wireless LAN, and as shown in
As shown in
Further, the high-frequency module 30 is configured in such a manner that the demultiplexer circuit 33 included in the reception portion 61 as well as the power amplifier circuits 38 and 39 and the demultiplexer circuit 40 included in the transmission portion 62 are provided in a multi-layer substrate, which will be described below.
Respective circuits that together form the high-frequency module 30 will now be described in detail.
The reception antenna connection terminal 32 is a terminal that establishes an electrical connection with the reception antenna 31.
The demultiplexer circuit 33 is a circuit that divides a reception signal received at the reception antenna 31 to two reception lines having different frequency bands from each other. The reception signals divided in the demultiplexer circuit 33 are outputted to the outside through the reception signal output terminals 34 and 35.
To be more specific, the demultiplexer circuit 33 comprises two types of band-pass filters, that is, high-pass and low-pass filters, to divide the reception signal received at the reception antenna 31 according to frequency bands. For example, one band-pass filter allows the passing of a reception signal in the 2.4 GHz band at the lower frequency, and the other band-pass filter allows the passing of a reception signal in the 5 GHz band at the higher frequency.
Transmission signals in different frequency bands are provided to the power amplifier circuits 38 and 39, which are inputted to the transmission signal input terminals 36 and 37, respectively.
The power amplifier circuits 38 and 39 are amplifier circuits that amplify the power of transmission signals in different frequency bands, such as the 2.4 GHz band and the 5 GHz band. To be more specific, each of the power amplifier circuits 38 and 39 comprises a high-frequency amplifier semiconductor device and a matching circuit.
The demultiplexer circuit 40 is a circuit that extracts a transmission signal from the power amplifier circuit 38 and a transmission signal from the power amplifier circuit 39, and supplies these signals to the transmission antenna 42.
To be more specific, the demultiplexer circuit 40 comprises two types of band-pass filters, that is, high-pass and low-pass filters, to allow the passing of the transmission signals in different frequency bands outputted from the power amplifier circuits 38 and 39. For example, one band-pass filter allows the passing of a transmission signal in the 2.4 GHz band at the lower frequency from the power amplifier circuit 38, and the other band-pass filter allows the passing of a transmission signal in the 5 GHz band at the higher frequency from the power amplifier circuit 39.
An example of the schematic structure of the high-frequency module of the first embodiment will now be described with reference to
The high-frequency module 30 is fabricated by laminating plural dielectric sheets and by forming respective circuit elements and terminals on the inner side or the surface of the multi-layer substrate in such a manner that the circuit elements and terminals are placed at their respective predetermined positions on the inner side or the surface of a multi-layer substrate 51, as shown in
That is, as shown in
Further, the demultiplexer circuit 40 shown in
The transmission signal output terminals 36 and 37 are electrically connected to the input sides of the power amplifier circuits 38 and 39 shown in
The demultiplexer circuit 33, the power amplifier circuits 38 and 39, and the demultiplexer circuit 40 that together form the high-frequency module are formed inside the multi-layer substrate 51 as shown in
Resin, such as epoxy, or a ceramic dielectric substance is used as a material of the dielectric sheet. Also, it is preferable to use a low-temperature co-fired ceramics substrate as the multi-layer substrate.
The high-frequency module 30 described above is configured in such a manner that the transmission portion 62 includes the power amplifier circuits 38 and 39; however, the power amplifier circuits 38 and 39 may be omitted when transmission power is relatively small. Such omission is possible in each embodiment described below.
The configuration in a case where the high-frequency module 30 of the first embodiment configured as described above is adapted to a wireless communications apparatus for a wireless LAN will now be described with reference to
As shown in
The reception portion 61 is able to process reception signals in both the 2.4 GHz band and the 5 GHz band. The reception portion 61 therefore includes, as shown in
The transmission portion 62 is able to process transmission signals in both the 2.4 GHz band and the 5 GHz band. The transmission portion 62 therefore includes a filter circuit 69, a mixer circuit 70, a high-frequency amplifier circuit 71, driver circuits 72 and 73, power amplifier circuits 38 and 39, a demultiplexer circuit 40, and a transmission antenna 42. Hence, in the transmission portion 62, a transmission signal in the 2.4 GHz band is amplified in the driver circuit 72 and the power amplifier circuit 38, and a transmission signal in the 5 GHz band is amplified in the driver circuit 73 and the power amplifier circuit 39.
A synthesizer circuit 74 and a digital signal processing circuit 75 are used commonly by the reception portion 61 and the transmission portion 62.
As has been described, the high-frequency module of the first embodiment is configured in such a manner that the demultiplexer circuit in the transmission portion and the demultiplexer circuit in the reception portion are provided, which eliminates the need for transmission/reception switching switches. It is thus possible to enhance the circuit performance by preventing a power loss associated with the use of the switching switches.
Also, according to the high-frequency module of the first embodiment, the demultiplexer circuits can be accommodated in the multi-layer substrate because they comprise combined filters. It is thus possible to reduce the size of the multi-layer substrate, which in turn makes it possible to reduce the size of the high-frequency module.
Further, according to the high-frequency module of the first embodiment, because the respective circuits in the module can be designed at one time, the connection impedance of the respective circuits can be matched in the interior, which enables the optimal characteristic adjustment to be performed for the overall circuit. In other words, it is no longer necessary to provide components to adjust the characteristic from circuit to circuit, and not only can the size be reduced, but also the design steps of the wireless terminal can be shortened, which in turn makes it possible to cut manufacturing costs.
The circuitry of a high-frequency module according to a second embodiment of the invention will now be described with reference to
A high-frequency module 30A of the second embodiment is based on the high-frequency module 30 shown in
In other words, as shown in
The structure of the high-frequency module 30A is basically the same as the structure of the high-frequency module 30 shown in
As has been described, the high-frequency module of the second embodiment is able to receive a subtle electric wave by including the low-noise amplifier circuits 63 and 64.
The circuitry of a high-frequency module according to a third embodiment of the invention will now be described with reference to
The high-frequency module 30 of the first embodiment shown in
Contrary to this, as shown in
As has been described, the high-frequency module of the third embodiment is configured in such a manner that the reception antenna 31 and the transmission antenna 42 are included inside. This eliminates the need for a connection tool between the demultiplexer circuits and both antennas; moreover, it is possible to achieve the satisfactory high-frequency characteristic by reducing attenuation due to the connections.
The circuitry of a high-frequency module according a fourth embodiment of the invention will now be described with reference to
The high-frequency module 30 of the first embodiment shown in
Hence, as shown in
The functions of the reception antenna connection terminal 82, the demultiplexer circuit 83, the reception signal output terminals 84 and 85 are the same as the functions of the reception antenna connection terminal 32, the demultiplexer circuit 33, the reception signal output terminals 34 and 35 shown in
The configuration of the other portion in the fourth embodiment is the same as the configuration of the first embodiment shown in
Further, the high-frequency module 30C is configured in such a manner that the respective circuits and terminals are placed on the inner side or the surface of the multi-layer substrate as are with the high-frequency module 30.
As has been described, because the high-frequency module of the fourth embodiment is able to process reception signals received at plural reception antennas for each antenna, the module can be adapted to a communications apparatus of the diversity reception system.
The circuitry of a high-frequency module according to a fifth embodiment of the invention will now be described with reference to
In the high-frequency module 30 of the first embodiment shown in
Hence, as shown in
Due to this addition, the reception signal output terminals 34 and 35 are replaced with balanced signal output terminals 34a and 34b that extract balanced signals transformed in the unbalanced-to-balanced transformer circuit 91, and the balanced signal output terminals 35a and 35b that extract balanced signals transformed in the unbalanced-to-balanced transformer circuit 92, respectively.
Further, the high-frequency module 30D is configured in such a manner that the respective circuits and terminals are placed on the inner side or the surface of the multi-layer substrate as with the high-frequency module 30.
As has been described, because the high-frequency module of the fifth embodiment additionally includes the unbalanced-to-balanced transformer circuits 91 and 92, it has an advantage that a differential amplifier circuit that receives and amplifies a balanced signal can be used as the amplifier circuit in the latter stage.
The circuitry of a high-frequency module according to a sixth embodiment of the invention will now be described with reference to
A high-frequency module 30D of the fifth embodiment shown in
Hence, as shown in
Also, due to this addition, the transmission signal input terminals 36 and 37 are replaced with balanced signal input terminals 36a and 36b that receive balanced signals to be supplied to the balanced-to-unbalanced transformer circuit 93, and balanced signal input terminals 37a and 37b that receive balanced signals to be supplied to the balanced-to-unbalanced transformer circuit 94, respectively.
Further, the high-frequency module 30E is configured in such a manner that the respective circuits and terminals are placed on the inner side or the surface of the multi-layer substrate as with the high-frequency module 30D.
As has been described, because the high-frequency module of the sixth embodiment additionally includes the balanced-to-unbalanced transformer circuits 93 and 94, balanced signals can be supplied to the power amplifier circuits 38 and 39 from the outside.
The configuration in a case where the high-frequency module 30E of the sixth embodiment configured as described above is adapted to a wireless communications apparatus for a wireless LAN will now be described with reference to
As shown in
The reception portion 101 is able to process reception signals in both the 2.4 GHz band and the 5 GHz band. Hence, as shown in
Hence, in the reception portion 101, a reception signal is demultiplexed to a signal in the 2.4 GHz band and a signal in the 5 GHz band in the demultiplexer circuit 33, which are transformed to balanced signals in the corresponding unbalanced-to-balanced transformer circuits 91 and 92. The balanced signals are then individually subjected to differential amplification in the corresponding low-noise amplifier circuits 63a and 64a, and processed in the common circuits thereafter.
The transmission portion 102 is able to process transmission signals in both the 2.4 GHz band and the 5 GHz band. Hence, the transmission portion 102 includes a filter circuit 69, a mixer circuit 70, a high-frequency amplifier circuit 71, driver circuits 72a and 73a, balanced-to-unbalanced transformer circuits 93 and 94, power amplifier circuits 38 and 39, a demultiplexer circuit 40, and a transmission antenna 42.
Hence, in the transmission portion 102, a transmission signal in the 2.4 GHz band is made to a balanced signal through differential amplification in the driver circuit 72a, and the balanced signal is transformed to an unbalanced signal in the balanced-to-unbalanced transformer circuit 93 followed by amplification in the power amplifier circuit 38. On the other hand, a transmission signal in the 5 GHz band is made to a balanced signal through differential amplification in the driver circuit 73a, and the balanced signal is transformed to an unbalanced signal in the balanced-to-unbalanced transformer circuit 94 followed by amplification in the power amplifier circuit 39.
A synthesizer circuit 74 and a digital signal processing circuit 75 are used commonly by the reception portion 101 and the transmission portion 102.
In each of the embodiments above, the high-frequency module 30 may be configured in such a manner that a directional coupling circuit (not shown) to extract part of the outputs of the power amplifier circuits 38 and 39 is provided between the power amplifier circuits 38 and 39 and the demultiplexer circuit 40 in the transmission portion 62, and the directional coupling circuit is provided inside the multi-layer substrate. When configured in this manner, the transmission outputs can be monitored.
As has been described, according to the invention, the transmission/reception switching switches can be omitted. Hence, not only can a power loss associated with the switching switches be prevented, but also the module can be reduced in size.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-192288 | Jul 2003 | JP | national |
