Patent Application
20240204412
The present disclosure relates to an antenna module and a communication device mounted with the same, and more specifically relates to a structure of an antenna module with built-in filter.
Japanese Unexamined Patent Application Publication No. 2001-267825 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2003-258547 (Patent Document 2) disclose an antenna device that includes a filter, which is integrally formed with an antenna in a dielectric substrate, and uses a radiating element of the antenna as a resonator of the filter. The configurations of Patent Documents 1 and 2 enable miniaturization of the antenna devices and improvement of antenna characteristics.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-267825
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-258547
In recent years, a configuration has been proposed in which an antenna device and a filter are integrated in a front-end circuit of wireless communication devices such as smartphones or cellular phones. There is still a strong demand for miniaturization of such wireless communication devices, and along with this, there is also a need for miniaturization of a front-end circuit itself. In particular, in so-called dual polarization type antenna devices that can radiate radio waves in two different polarization directions, a filter should be arranged for each polarization and accordingly, the filter itself also should be miniaturized.
Regarding filter characteristics, it is also desirable to increase attenuation in a non-pass band and to increase steepness in the vicinity of a pass band.
The present disclosure has been made to solve the above problems and an object of the present disclosure is to realize miniaturization of an antenna module in which a filter device is incorporated and improvement of filter characteristics.
An antenna module according to an aspect of the present disclosure includes: a dielectric substrate; a radiating element that is arranged in the dielectric substrate; a first ground electrode and a second ground electrode that are arranged to be opposed to the radiating element; and a resonance circuit. The resonance circuit is arranged between the radiating element and the first ground electrode and includes a plurality of resonators. The radiating element and the resonance circuit constitute a filter device. The resonance circuit includes: an input line that receives a radio frequency signal from a feed circuit; a first resonance portion that is coupled with the input line; and a second resonance portion that is coupled with the input line and the radiating element. A second ground electrode is arranged between the radiating element and the input line. The first resonance portion functions as an extracted pole unit (EPU) generating an attenuation pole in an outside of a pass band of the filter device. The input line is arranged between the first resonance portion and the second resonance portion.
An antenna module according to another aspect of the present disclosure includes: a dielectric substrate; a radiating element that is arranged in the dielectric substrate; a first ground electrode and a second ground electrode that are arranged to be opposed to the radiating element; a first resonance circuit; and a second resonance circuit. Each of the first resonance circuit and the second resonance circuit includes a plurality of resonators and is arranged between the radiating element and the first ground electrode. The radiating element and the first resonance circuit constitute a first filter device and the radiating element and the second resonance circuit constitute a second filter device. Each of the first resonance circuit and the second resonance circuit includes: an input line that receives a radio frequency signal from a feed circuit; a first resonance portion that is coupled with the input line; and a second resonance portion that is coupled with the input line and the radiating element. A second ground electrode is arranged between the radiating element and the input line of the first resonance circuit and between the radiating element and the input line of the second resonance circuit. The first resonance portion functions as an EPU generating an attenuation pole in an outside of a pass band of a corresponding filter device. The input line is arranged between the first resonance portion and the second resonance portion. The radiating element is capable of radiating a radio wave in a first polarization direction and a second polarization direction, which is different from the first polarization direction. A signal passing through the first resonance circuit is supplied to a feed point for radiating a radio wave of the first polarization direction in the radiating element. A signal passing through the second resonance circuit is supplied to a feed point for radiating a radio wave of the second polarization direction in the radiating element.
The antenna module according to the present disclosure includes the radiating element and the resonance circuit that constitute the filter device. The resonance circuit includes the first resonance portion and the second resonance portion that are branched from the input line, the first resonance portion functions as an EPU, and the second resonance portion is coupled to the radiating element. In the antenna module according to the present disclosure, a pass band can be defined by the radiating element and the second resonance portion with a relatively simple structure and an attenuation pole can be formed in a non-pass band by the first resonance portion. Accordingly, miniaturization and improvement of filter characteristics can be realized in the antenna module in which a filter device is incorporated.
Embodiments according to the present disclosure will be described in detail below with reference to the accompanying drawings. Here, the same reference characters are given to the same or corresponding portions and the description thereof will not be repeated.
Referring to
The RFIC 110 includes switches 111A to 111D, 113A to 113D, and 117; power amplifiers 112AT to 112DT; low noise amplifiers 112AR to 112DR; attenuators 114A to 114D; phase shifters 115A to 115D; a signal synthesizer/demultiplexer 116; a mixer 118; and an amplifying circuit 119.
In transmitting a radio frequency signal, the switches 111A to 111D and 113A to 113D are switched to the power amplifiers 112AT to 112DT sides and the switch 117 is connected to a transmission amplifier of the amplifying circuit 119. In receiving a radio frequency signal, the switches 111A to 111D and 113A to 113D are switched to the low noise amplifiers 112AR to 112DR sides and the switch 117 is connected to a reception amplifier of the amplifying circuit 119.
A signal transmitted from the BBIC 200 is amplified in the amplifying circuit 119 and up-converted in the mixer 118. A transmission signal that is the up-converted radio frequency signal is demultiplexed into four signals in the signal synthesizer/demultiplexer 116 and fed to respective mutually-different radiating elements 121 through four respective signal paths. At this time, the directivity of the antenna device 120 can be adjusted by individually adjusting phase levels of the phase shifters 115A to 115D arranged on respective signal paths.
Reception signals which are radio frequency signals received by respective radiating elements 121 pass through four respective different signal paths and synthesized in the signal synthesizer/demultiplexer 116. The synthesized reception signal is down-converted in the mixer 118 and amplified in the amplifying circuit 119 to be transmitted to the BBIC 200.
The resonance circuit 150 includes resonance circuits 1501 to 1504. The resonance circuits 1501 to 1504 are connected to the switches 111A to 111D in the RFIC 110 respectively. Each of the resonance circuits 1501 to 1504 and a corresponding radiating element 121 constitute a filter device to have a function to attenuate a signal in a specific frequency band. The filter devices constituted by the resonance circuits 1501 to 1504 and respective radiating elements 121 may be a band pass filter, a high pass filter, a low pass filter, or a combination of these. Radio frequency signals from the RFIC 110 pass through the resonance circuits 1501 to 1504 to be supplied to the corresponding radiating elements 121.
For radio frequency signals in the millimeter wave band, more noise components tend to be introduced as a transmission line is elongated. Therefore, it is preferable to decrease a distance between the resonance circuit 150 and the radiating element 121 as short as possible. Namely, it is possible to suppress radiation of an unwanted wave from the radiating element 121 by allowing a radio frequency signal to pass through the resonance circuit 150 immediately before radiating the radio frequency signal from the radiating element 121. Further, an unwanted wave included in a reception signal can be removed by allowing the reception signal to pass through the resonance circuit 150 immediately after receiving the reception signal at the radiating element 121.
Here,
The RFIC 110 is one chip of integrated circuit component having the above-described circuit configuration, for example. Alternatively, devices (switch, power amplifier, low noise amplifier, attenuator, phase shifter) corresponding to each radiating element 121 in the RFIC 110 may be provided as one chip of integrated circuit component for each corresponding radiating element 121.
The configuration of the antenna module 100 according to this first embodiment will now be described in detail with reference to
An example in which the antenna module 100 includes one radiating element 121 will be described with reference to
Referring to
The dielectric substrate 130 is, for example, a low temperature co-fired ceramics (LTCC) multi-layer substrate; a multi-layer resin substrate, which is formed by laminating a plurality of resin layers made of resin such as epoxy or polyimide; a multi-layer resin substrate, which is formed by laminating a plurality of resin layers made of liquid crystal polymer (LCP) having a lower dielectric constant; a multi-layer resin substrate, which is formed by laminating a plurality of resin layers made of fluorine resin; or a multi-layer substrate made of ceramics other than LTCC. Here, the dielectric substrate 130 does not necessarily have to have a multi-layer structure but may be a single-layer substrate.
The dielectric substrate 130 has a substantially rectangular parallelepiped shape, and the radiating element 121 is arranged on an upper surface 131 (a surface in the positive direction of the Z axis) of the dielectric substrate 130 or in a dielectric layer which is in the inside and close to the upper surface 131. The ground electrode GND1 having a flat-plate shape is arranged over the entire surface of a dielectric layer which is in the inside and close to a lower surface 132 (a surface in the negative direction of the Z axis) of the dielectric substrate 130 in a manner to be opposed to the radiating element 121. Further, the ground electrode GND2 having a flat-plate shape is arranged in a dielectric layer between the radiating element 121 and the ground electrode GND1, in a manner to be opposed to the radiating element 121. The ground electrode GND2 and the radiating element 121 constitute an antenna.
On the lower surface 132 of the dielectric substrate 130, the RFIC 110 is mounted with solder bumps 160 interposed therebetween. However, the RFIC 110 may be connected to the dielectric substrate 130 with a multipole connector instead of solder connection.
The resonance circuit 150 is arranged in a wiring layer between the ground electrode GND1 and the ground electrode GND2. The resonance circuit 150 includes an input line 155 and resonators 151 to 154. As illustrated in
In the resonance circuit 150, a plurality of vias VG are arranged in a manner to surround the resonators 151 to 154. The vias VG are connected with the ground electrodes GND1 and GND2. The resonance circuit 150 further includes a flat-plate electrode PG, which has a substantially C shape and connects the vias VG with each other. One end of each of the resonators 151 to 154 is connected to the flat-plate electrode PG. The input line 155 extends into the resonance circuit 150 through a cutout portion 180 of the flat-plate electrode PG. The vias VG and the flat-plate electrode PG function as shields and suppress electromagnetic field coupling of the resonators 151 to 154 and the input line 155 with other pieces of wiring arranged in the wiring layer.
Regarding the input line 155, a radio frequency signal is transmitted from the RFIC 110 to the input line 155 by the solder bumps 160 connected to the RFIC 110 with the via 171 interposed therebetween.
The resonators 151 and 152 are arranged in a dielectric layer between the dielectric layer, in which the input line 155 is arranged, and the dielectric layer, in which the ground electrode GND1 is arranged. The resonator 152 is arranged on a position closer to the input line 155 than the resonator 151, and part of the resonator 152 overlaps with the input line 155 in plan view in the normal direction of the dielectric substrate 130. The resonator 152 is electromagnetically coupled with the resonator 151 and the input line 155. The resonators 151 and 152 constitute a resonance portion 51 functioning as an EPU, which generates an attenuation pole. The resonators 151 and 152 are thus added other than a series path with which a signal passes through the filter device, being able to provide an attenuation pole in a non-pass band on the higher frequency side and/or the lower frequency side than the pass band of the filter device. Here, the resonators 151 and 152 do not necessarily have to be arranged in the same dielectric layer as long as the resonators 151 and 152 can be electromagnetically coupled with each other.
The resonators 153 and 154 are arranged in a dielectric layer between the dielectric layer, in which the input line 155 is arranged, and the dielectric layer, in which the ground electrode GND2 is arranged. The resonator 153 is arranged on a position closer to the input line 155 than the resonator 154, and part of the resonator 153 overlaps with the input line 155 in plan view in the normal direction of the dielectric substrate 130. The resonator 153 is electromagnetically coupled with the resonator 154 and the input line 155. The resonator 154 is connected with a feed point SP1 of the radiating element 121 via the vias 172 and 173 and a flat-plate electrode 156. The feed point SP1 is arranged at a position offset from the center of the radiating element 121 in the positive direction of the Y axis. When a radio frequency signal is supplied to the feed point SP1, a radio wave whose polarization direction is in the Y-axis direction is radiated from the radiating element 121.
The resonators 153 and 154 constitute a resonance portion 52. The pass band of the filter device is defined by the input line 155, the resonators 153 and 154, and the radiating element 121. When the resonance portion 52 is arranged at a position closer to the radiating element 121 than the resonance portion 51, feed wiring connecting the resonator 154 with the radiating element 121 can be shortened, being able to reduce a transmission loss. Here, the resonators 153 and 154 do not necessarily have to be arranged in the same dielectric layer as long as the resonators 153 and 154 can be electromagnetically coupled with each other.
As described, the resonance portion 51, which is composed of the resonators 151 and 152, and the resonance portion 52, which is composed of the resonators 153 and 154, are arranged at positions in mutually opposite directions with respect to the input line 155. Thus, the resonance portion 51 and the resonance portion 52 are not directly coupled with each other.
Generally, in a filter device composed of a plurality of resonators, a configuration for forming a skip-over coupling among resonators is known as a method for providing an attenuation pole in a non-pass band. In this configuration, a structure is required in which a certain resonator in the filter device skips over one or more adjacent resonators to be coupled with another resonator. Accordingly, the shapes and arrangement of the resonators are complicated and the overall size of the filter device is sometimes increased.
On the other hand, the resonance portion 51 functioning as an EPU is provided in the filter device 50 configured in the antenna module 100 according to the first embodiment, being able to provide an attenuation pole in a non-pass band without using skip-over coupling. Skip-over coupling is not required and therefore, the filter device can be configured with a relatively simple structure, in which λ/4 resonators which are belt-like flat-plate electrodes are arranged adjacent to each other as respective resonators. Thus, for the filter device 50 according to the first embodiment, the overall size of the filter device can be reduced compared to a filter device employing skip-over coupling, and attenuation characteristics of the filter device 50 can be improved by providing an attenuation pole in a non-pass band with an EPU.
Referring to
As described above, the antenna module 100 according to the first embodiment includes the filter device 50 that has the resonance portions 51 and 52, which are branched from the input line 155, an attenuation pole is formed by the resonance portion 51, and a pass band is formed by the resonance portion 52 and the radiating element 121. The antenna module 100 allows the resonance portion 51 to function as an EPU and thus, a relatively simple structure free from employing the skip-over coupling can be achieved. Accordingly, desired attenuation characteristics can be realized by forming an attenuation pole and the size of the filter device 50 can be reduced at the same time.
The “ground electrodes GND1 and GND2” in the first embodiment correspond to a “first ground electrode” and a “second ground electrode” in the present disclosure respectively. The “resonance portions 51 and 52” in the first embodiment correspond to a “first resonance portion” and a “second resonance portion” in the present disclosure respectively. The “resonators 151 to 154” in the first embodiment correspond to a “first resonator”, a “second resonator”, a “third resonator”, and a “fourth resonator” in the present disclosure respectively. The “vias 172 and 173” in the first embodiment both correspond to a “second via” in the present disclosure. The “via VG” in the first embodiment corresponds to a “third via” in the present disclosure.
A first modification will describe a configuration obtained by adding a configuration for adjusting a coupling amount between resonators in the resonance portion 51.
Referring to
With the addition of such an adjustment element, design parameters are increased in design of a filter device. Therefore, characteristics are further improved by appropriately adjusting the coupling amount.
The “adjustment element 157” in the first modification corresponds to a “third adjustment element” in the present disclosure.
A second modification will describe a configuration in which the resonance portions 51 and 52 and the input line 155 are arranged in the same dielectric layer.
Referring to
In addition, the resonance circuit 150B is further provided with the adjustment element 157 for adjusting the coupling amount between the resonator 151 and the resonator 152, an adjustment element 158 for adjusting the coupling amount between the input line 155 and the resonator 152, and an adjustment element 159 for adjusting the coupling amount between the input line 155 and the resonator 153.
The adjustment elements 157, 158, and 159 are arranged in a dielectric layer between the dielectric layer, in which the resonance portions 51 and 52 and the input line 155 are arranged, and the dielectric layer, in which the ground electrode GND1 is arranged. Here, part or all of the adjustment elements 157, 158, and 159 may be arranged in a dielectric layer between the dielectric layer, in which the resonance portions 51 and 52 and the input line 155 are arranged, and the dielectric layer, in which the ground electrode GND2 is arranged.
The adjustment element 157 has a substantially rectangular shape and partially overlaps with the resonator 151 and the resonator 152 in plan view in the normal direction of the dielectric substrate 130. By adjusting an area, in which each resonator overlaps with the adjustment element 157, and/or distance between each resonator and the adjustment element 157, the coupling amount between the resonator 151 and the resonator 152 can be adjusted.
The adjustment element 158 has a substantially rectangular shape and partially overlaps with the resonator 152 and the input line 155 in plan view in the normal direction of the dielectric substrate 130. By adjusting an area, in which the resonator 152 and the input line 155 overlap with the adjustment element 158, and/or distance from the resonator 152 and the input line 155 to the adjustment element 158, the coupling amount between the resonator 152 and the input line 155 can be adjusted.
The adjustment element 159 has a substantially rectangular shape and partially overlaps with the resonator 153 and the input line 155 in plan view in the normal direction of the dielectric substrate 130. By adjusting an area, in which the resonator 153 and the input line 155 overlap with the adjustment element 159, and/or distance from the resonator 153 and the input line 155 to the adjustment element 159, the coupling amount between the resonator 153 and the input line 155 can be adjusted.
Not shown in
Each resonance portion and the input line are thus arranged in the same dielectric layer and accordingly, the dimension in the Z-axis direction of the resonance circuit can be reduced, being able to realize low-profile antenna module. Further, with the addition of the adjustment elements, the coupling amount between the resonators of each resonance portion and the coupling amount between each resonance portion and the input line can be adjusted. As a result, antenna characteristics can be improved.
The “adjustment element 158”, the “adjustment element 159”, and the “adjustment element 157” in the second modification correspond to a “first adjustment element”, a “second adjustment element”, and the “third adjustment element” in the present disclosure respectively.
A third modification will describe another coupling mode between a resonance circuit and a radiating element.
Referring to
In the configuration in which the resonator 154 and the radiating element 121 are directly connected with each other by vias or the like as the antenna module 100 according to the first embodiment, unwanted resonance may occur due to pieces of feed wiring such as the vias and cause noise. By employing the configuration using no feed wiring between the resonator 154 and the radiating element 121 as the antenna module 100C, unwanted resonance caused by the feed wiring can be suppressed and the antenna characteristics can be improved.
Here, in the configuration in which all of the vias 172 and 173 and the flat-plate electrode 156 are removed, coupling between the resonator 154 and the radiating element 121 may be weakened depending on the distance between the resonator 154 and the radiating element 121 and a sufficient antenna gain may be unable to be secured. Therefore, the resonator 154 and the radiating element 121 may be capacitively coupled with each other by employing the configuration in which a part of pieces of feed wiring is removed to the extent that unwanted resonance can be reduced. For example, the flat-plate electrode 156 and the radiating element 121 may be capacitively coupled to each other by employing the configuration in which the via 173 of the antenna module 100 is removed.
A fourth modification will describe a configuration in which feed wiring between a resonance circuit and a radiating element is used as part of a resonator on a final stage of the resonance circuit.
Referring to
The flat-plate electrode 156D and the via 172D correspond to the flat-plate electrode 156 and the via 172 included in the pieces of feed wiring of the antenna module 100 according to the first embodiment respectively. That is, the flat-plate electrode 156D is arranged in a layer between the dielectric layer, in which the ground electrode GND2 is arranged, and the dielectric layer, in which the radiating element 121 is arranged, and is connected to the flat-plate electrode 154D by the via 172D.
In the antenna module 100 according to the first embodiment, the resonator 154 is composed of the flat-plate electrode having the length of λ/4 and is connected to the radiating element 121 by the pieces of feed wiring (the vias 172 and 173 and the flat-plate electrode 156). In the antenna module 100D, part of the vias and the flat-plate electrode, which are used as the pieces of feed wiring in the above, is used as part of the resonator 154* and accordingly, unwanted resonance caused by the vias can be prevented and the non-contact coupling amount between the resonance circuit 150D and the radiating element 121 can be secured.
The “flat-plate electrodes 154D and 156D” in the fourth modification correspond to a “first flat-plate electrode” and a “second flat-plate electrode” in the present disclosure respectively. The “via 172D” in the fourth modification corresponds to a “first via” in the present disclosure.
A second embodiment will describe a configuration in which features of the present disclosure are applied to a so-called dual polarization type antenna module that can radiate radio waves in two different polarization directions from a radiating element.
The resonance circuit 150X is connected to a feed point SPX of the radiating element 121 via feed wiring 170X, which is composed of a via and a flat-plate electrode. The feed point SPX is arranged at a position offset from the center of the radiating element 121 in the positive direction of the X axis. By supplying a radio frequency signal to the feed point SPX via the resonance circuit 150X, a radio wave whose polarization direction is in the X-axis direction is radiated from the radiating element. The resonance circuit 150X and the radiating element 121 constitute a filter device for a radio wave whose polarization direction is in the X-axis direction (first filter device).
The resonance circuit 150Y is connected to a feed point SPY of the radiating element 121 via feed wiring 170Y, which is composed of a via and a flat-plate electrode. The feed point SPY is arranged at a position offset from the center of the radiating element 121 in the positive direction of the Y axis. By supplying a radio frequency signal to the feed point SPY via the resonance circuit 150Y, a radio wave whose polarization direction is in the Y-axis direction is radiated from the radiating element. The resonance circuit 150Y and the radiating element 121 constitute a filter device for a radio wave whose polarization direction is in the Y-axis direction (second filter device).
The resonance circuits 150X and 150Y can be configured to have a relatively compact structure as described in the first embodiment. Accordingly, in a dual polarization type antenna module such as the antenna module 100E as well, a resonance circuit can be arranged close to the radiating element 121. As a result, miniaturization of the antenna module and improvement of antenna characteristics can be achieved at the same time.
The configuration of each modification of the first embodiment is applicable to the configuration of the second embodiment to the extent that there is no contradiction.
The “resonance circuits 150X and 150Y” in the second embodiment correspond to a “first resonance circuit” and a “second resonance circuit” in the present disclosure respectively. The “X-axis direction” and the “Y-axis direction” in the second embodiment correspond to a “first polarization direction” and a “second polarization direction” in the present disclosure respectively.
The embodiments disclosed here should be considered exemplary and not restrictive in all respects. The scope of the present disclosure is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all changes within the scope and meaning equivalent to the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-139853 | Aug 2021 | JP | national |
This is a continuation application of PCT/JP2022/029670, filed on Aug. 2, 2022, designating the United States of America, which is based on and claims priority to Japanese Patent Application No. JP 2021-139853 filed on Aug. 30, 2021. The entire contents of the above-identified applications, including the specifications, drawings and claims, are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/029670 | Aug 2022 | WO |
| Child | 18591003 | US |
