Transceiver device

A transceiver device includes a dielectric substrate, a ring member that is welded onto the dielectric substrate thereby forming a plurality of cavities, a cover that is welded onto the ring member, and at least one semiconductor device that is arranged in each of the cavities. The ring member has at least one passage that communicates between adjacent cavities. The passage is provided at a position shifted by substantially λg/4 or substantially n×λg/2+λg/4 from a center axis of the cavities. If there are two or more passages, the passages are arranged at a λg/2 interval, and one of the passages closest to the center axis is at a position shifted by substantially λg/4 from the center axis.

TECHNICAL FIELD

The present invention relates to a transceiver device that is used mainly in a microwave band and a millimeter-wave band.

BACKGROUND ART

A high-frequency package on which a high-frequency semiconductor device, which operates in a high frequency band such as a microwave band and a millimeter-wave band, is mounted is often housed in a cavity that is airtightly and electrically shielded with a metallic frame or the like, considering environment resistance, operational stability, corrosion resistance, and the like.

Patent Document 1 discloses a technique in which a control signal line is wired on a dielectric multilayer substrate, a metallic frame is arranged on the dielectric multilayer substrate, and a microwave integrated circuit is mounted in the metallic frame, thereby improving input/output isolation of the integrated circuit, and in which airtight sealing is enabled by welding.

DISCLOSURE OF INVENTION

Problem to be Solved by the Invention

In the above conventional technique, however, a transmission cavity and a reception cavity are spatially independently structured to ensure electrical isolation. Therefore, in the conventional technique, water saturation time is short in the cavity having small volume, and it has been impossible to mount a microwave integrated circuit or the like that has low moisture resistance.

The present invention has been achieved in view of the above problems, and it is an object of the present invention to obtain a transceiver device that can mount a microwave integrated circuit having low moisture resistance while ensuring electrical isolation.

Means for Solving Problem

To solve the above problems and to achieve the above objects, the present invention provides a transceiver device includes a plurality of cavities defined by a dielectric substrate, a ring member that has a frame form having a plurality of spaces and that is connected on the dielectric substrate, and a cover member that is connected on the ring member, and semiconductor devices for transmission and reception those mounted in the cavities, wherein a ventilation hole that communicates the cavities is formed, and the ventilation hole is arranged at a position that is shifted by substantially λg/4 from a cavity center, at a position that is shifted by substantially n×λg/2+μg/4 (n: positive integer) from the cavity center, or at a plurality of positions at μg/2 intervals from the position that is shifted by substantially λg/4 from the cavity center, where λg is a resonance wavelength according to a cavity size.

EFFECT OF THE INVENTION

According to an aspect of the present invention, a ventilation hole that communicates a plurality of cavities is formed, and the ventilation hole is arranged at a position that is shifted by substantially λg/4 from a cavity center, at a position that is shifted by substantially n×λg/2+μg/4 (n: positive integer) from the cavity center, or at a plurality of positions at λg/2 intervals from the position that is shifted by substantially λg/4 from the cavity center, where λg is a resonance wavelength that depends on sizes of the cavities. Therefore, it is possible to mount a microwave integrated circuit that has low moisture resistance while maintaining electrical isolation between the respective cavities.

EXPLANATIONS OF LETTERS OR NUMERALS

BEST MODE(S) FOR CARRYING OUT THE INVENTION

Exemplary embodiments of a transceiver device according to the present invention will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

First Embodiment

FIG. 1is a plan view of a configuration of a transceiver device according to a first embodiment of the present invention, andFIG. 2is a partially exploded perspective view thereof. As shown inFIGS. 1 and 2, a transceiver device according to the first embodiment includes a multilayer dielectric substrate (hereinafter, “substrate”)1, a metallic ring member (seal ring)2, and a metallic cover member (hereinafter, “cover”)3as a lid. A ground conductive layer is formed on a surface of the substrate1, and the ring member2and the cover3are grounded. The ring member2has a rectangular shape formed with two rectangles attached to each other, thereby forming two rooms for a transmission cavity4and a reception cavity5. A high-frequency semiconductor device (MMIC) for transmission or the like is mounted on the substrate1inside the transmission cavity4, and an MMIC for reception or the like is mounted on the substrate1inside the reception cavity5. The transmission cavity4is arranged in a small size that is half the size of the reception cavity5or less.

The substrate1and bottom and corner portions of the ring member2are fixed to each other with a brazing material (bonding material)13such as solder and silver solder, and an upper surface of the ring member2and the cover3are fixed to each other by welding with a brazing material (bonding material)8for welding. By bonding the ring member2and the cover3, a plurality of MMICs6and7are airtightly sealed. Moreover, the ring member2and the cover3prevent leakage to the outside of the radiation from the MMICs6and7that are provided on the substrate1. Namely, the ring member2and the cover3form an electromagnetic shielding member that covers a part of a surface layer of the substrate1and the MMICs6and7.

In the first embodiment, a part of a portion sectioning between the transmission cavity4and the reception cavity5in a welded portion8connecting the ring member2and the cover3, that is, a part of an upper surface portion of a frame of the ring member for partitioning between the transmission cavity4and the reception cavity5, and a portion of the cover3corresponding to the part are not welded, thereby providing a non-welded portion9. With this arrangement, a ventilation hole10that communicates between the transmission cavity4and the reception cavity5is provided.

Compared with the case that the ventilation hole10is not provided, because the transmission cavity4is arranged in a small size that is half the size of the reception cavity5or less as described above, the water saturation time of the transmission cavity4is short and it is impossible to mount an MMIC or the like having low moisture resistance in the transmission cavity4. According to the first embodiment, the ventilation hole10enables the transmission cavity4and the reception cavity5to be regarded as a single large volume cavity being combined with the other cavity. Specifically, the ventilation hole10communicates air between the cavities4and5, thereby virtually making the spatial volume (volume) of the transmission cavity4large by adding the spatial volume of the reception cavity5to the spatial volume (volume) of the transmission cavity4. Accordingly, an amount of water vapor saturation of the transmission cavity increases, which makes it possible to mount an MMIC having low moisture resistance even in the transmission cavity4that has small volume.

However, there is a problem that the electrical isolation is degraded due to, through the ventilation hole10, leakage of electric wave of the transmission cavity4to the reception cavity5, or leakage of electric wave of the reception cavity5to the transmission cavity4. To solve the problem, in the first embodiment, the ventilation hole10is arranged at a position that is shifted by λg/4 from a cavity center12, thereby ensuring the electrical isolation between the transmission cavity4and the reception cavity5even if the transmission cavity4and the reception cavity5are communicated, where λg indicates a wavelength of resonance frequency that depends on sizes of the cavities. The size, the position, and the like of the ventilation hole10are described in detail later.

Although in the above example, the two cavities are different in volume, the transmission cavity4and the reception cavity5can have equivalent volume. Namely, even when the transmission cavity4and the reception cavity5are equivalent in volume, if the ventilation hole10is arranged at a position that is shifted by λg/4 from the center of the cavity, an effect can be obtained that the water saturation properties of the cavities4and5is approximated as close as possible (that is, to avoid condition of one of the cavities worse than that of the other) while maintaining the electrical isolation.

Hole width L and hole height H of the ventilation hole (space)10are considered next. The width L of the ventilation hole10is set to be smaller than λg/2 (in which λg is a wavelength of resonance frequency determined by a cavity size of a package used in working frequencies of MMIC, that is, a waveband of 50 to 100 gigahertz, and resonance frequency is in a 70 to 80 gigahertz band), and is suitable to be, for example, 3 μg/8 or less (for example, when the resonance frequency is in 76 to 77 gigahertz band, λg/2=2 mm, and therefore, 3 μg/8=1.5 mm or less is suitable). In this example, in view of interference suppression (isolation) effect, manufacture variation, workability, and the like, it is preferable to set the width L of the ventilation hole10to about λg/4 (for example, when the resonance frequency is 77 gigahertz, λg/2=2 mm, and therefore, about λg/4=1 mm is preferable). This is because a width of λg/2 or less is required as such a width L of the ventilation hole that can cause cut-off frequency of a waveguide. However, it is preferable to suppress a passage loss as much as possible to suppress the interference between the transmission cavity4and the reception cavity5, and considering a result of electromagnetic analysis, it is preferable to set to 3 λg/8 or less in practice.

Moreover, when the hole height (space height) H of the ventilation hole10is 0.001 to 0.1 millimeter, the passage loss can be sufficiently suppressed. If the height H is larger than 0.1 millimeter, just the non-welded portion9is insufficient, and it becomes necessary to separately provide a special groove for the ventilation hole on the upper surface of the ring member2. In this case, there is a disadvantage of decrease of productivity. If decrease of the productivity does not matter, a groove special for the ventilation hole can be separately provided on the upper surface of the ring member2, however, the height H of the ventilation hole10is still required to be set to λg/2 or less. Even though the width L of the ventilation hole10is about λg/4, because the transmission cavity4and the reception cavity5are communicated, it is possible to cause the water situation time to be sufficiently longer compared to the case that the transmission cavity4and the reception cavity5are isolated. However, as the width L and the height H of the ventilation hole10become smaller than λg/4, airflow through the ventilation hole gradually decreases. Therefore, the width and the height of the ventilation hole are set not to weaken the effect of averaging the water saturation amount. Incidentally, because the molecular diameter of water is 0.09572 nm×2 or smaller, width and height are required to be larger than this. When a section of the ventilation hole10was measured after welding the cover (lid)3to the ring member2, it was confirmed that the height H was 1 μm or higher. It was confirmed that in this condition, MMIC having low moisture resistance could operate without problem under such an environment that temperature is 80° C. or higher, and humidity is 80% or higher.

Isolation properties of the transmission cavity4and the reception cavity5are shown inFIG. 3. The vertical axis represents a leakage amount (dB) and the horizontal axis represents the width L of the ventilation hole10inFIG. 3. As for the height of the ventilation hole10, 0.01 millimeter, 0.05 millimeter, and 0.1 millimeter were used, and as for the position of the ventilation hole10, a position that is shifted by λg/4 from the cavity center12was used. As shown inFIG. 3, when the width L of the ventilation hole10is smaller than 2 millimeters, the leakage amount drastically decreases, and further, when the width L is 1 millimeter, the leakage amount decrease much compared to the case of 2 millimeters.

The position of the ventilation hole (space) is considered next. It was confirmed in electrolytic analysis that when the ventilation hole10is arranged at a position that is shifted by about λg/4 (for example, when the resonance frequency is 77 gigahertz, λg/2=2 mm, and therefore, 1 millimeter) from the cavity center12at a boundary between the transmission cavity4and the reception cavity5, the transmission/reception isolation becomes the lowest (=the passage loss can be minimized).FIG. 4depicts a resonance waveform when the transmission cavity4and the reception cavity5are communicated through the ventilation hole10. InFIG. 4, a resonance mode order n=7(m+1+n=8), and a resonance waveform having seven resonance waves is seen. In this case, the electric-field peaks (antinodes) are seven. From this resonance waveform, it is found that leakage occurs at a center position of the transmission cavity4. This indicates that amplitude corresponding to a TE10n mode (n-order mode) of the transmission cavity increases abruptly in frequency (for example, 76 to 77 gigahertz of resonance frequency) that highly influences the wavelength λg of the resonance frequency. Namely, it is found that an amount of leakage is large due to the band if the ventilation hole10is provided at the center position.

Changes in the isolation property when a shifted point D of the ventilation hole10indicated by a distance from the center position is changed from 0 millimeter to 2.5 millimeters are shown inFIG. 5(a case that the height of the ventilation hole10H=0.1 mm and the width B=1 mm) and inFIG. 6(a case that the height of the ventilation hole10H=0.01 mm and the width B=1.8 mm). The vertical axis represents the leakage amount and the horizontal axis represents the shifted position D inFIGS. 5 and 6. As shown inFIGS. 5 and 6, it is found that the leakage amount, which is maximized at the center position, scarcely changes in a range from the center position to around a point of around 1 millimeter shift, and decrease at around the point shifted by 1 millimeter from the center position. Particularly, around the point of 1 millimeter shift (corresponding to d=1.18 mm and d=λg/4), the transmission/reception isolation is minimized (10 dB to 20 dB lower than the leakage amount at the center position). Although, if the width B is set to 2 millimeters, a singular point at which the leakage amount temporarily becomes large appears when the shifted point D is in a range from 0 millimeter to 2 millimeters, it is found that a band having the smallest leakage amount is located at the position shifted by λg/4 from the center in the entire band of 70 gigahertz to 80 gigahertz. This is because an n-order resonance mode that depends on a cavity length is generated, and the cavity center is located a position corresponding to the antinode of the resonance waveform. Accordingly, the leakage amount is maximized at the position of the cavity center, and the leakage amount is minimized at the position shifted by λg/4 from the cavity center that is located corresponding to an antinode. Therefore, if the ventilation hole10is arranged at the position shifted by λg/4 from the electric-field peak (antinode) (namely, the position of electric-field minimum point (node)) of the resonance wave that is generated by the cavity resonance, the leakage amount is minimized, thereby the leakage property (isolation property) is improved.FIG. 7exemplifies the resonance waveform inside the transmission cavity.

FIG. 8depicts a calculation model of the transmission cavity4, in which the length in a direction of short side of the transmission cavity4is denoted as A, the height is denoted as B, and the length in the direction of long side (length in a direction of signal propagation) is denoted as C. From
λ0=C0×1000/F
λ1=C0×1000/{F·{Er}1/2}
λg=1/{1-(λ1/2·C)2}1/2
where C0: speed of light (=2.98×108m/s), Er: relative permittivity (=1.00), and F: signal frequency (Hz), if the length C in the direction of long side is arbitrarily set to 10 to 20 millimeters and F=77 GHz, the resonance wavelength λg/2=2 mm. According to this result, an amount λg/4 of shift from the cavity center (antinode) to a position of node is 1 millimeter.

Furthermore, if a wavelength of an actual space is calculated as follows, the resonance wavelength kg can be acquired more accurately, thereby enabling to accurately set the positions of antinode and node. Equation (1) below is to calculate resonance frequency of a rectangular parallelepiped model shown inFIG. 8. When the length A of short side and the height B are set to 1 to 5 millimeters, and the length C of long side is set to 10 to 20 millimeters appropriately, a condition in which resonance occurs at frequency near 76 to 77 gigahertz is l=1, m=0, and n=7 fromFIG. 9, also when equation (1) below is applied. Unique resonance frequency TE(l, m, n) when mode orders l, m, n in directions of each side are appropriately set is shown inFIG. 9

T⁢⁢E⁡(l,m,n)=1000⁢C0Er×(12⁢A)2+(m2⁢B)2+(n2⁢C)2(1)
where l represents a mode order in the direction of short side of the transmission cavity4, m represents a mode order in the direction of height of the transmission cavity4, and n represents a mode order in the direction of long side of the transmission cavity4.

Consequently, from the number of the resonance waves in the direction of long side of the cavity (Direction C) being seven, by dividing the length C in the direction of long side of the cavity by seven, the resonance wavelength λg is acquired. Based on this result, to shift the position from the center (antinode) of the cavity to the position of node, the shift amount λg/4 is set to approximately 1 millimeter (for example, λg/4=1.18 mm).

According to the first embodiment, the ventilation hole10is arranged between the transmission cavity4and the reception cavity5at a position shifted by λg/4 from the cavity center12. Therefore, it is possible to virtually increase the volume of the transmission cavity4that has actually small volume while maintaining the electrical isolation between the transmission cavity4and the reception cavity5, thereby increasing the water saturation amount of the transmission cavity4. As a result, it becomes possible to mount a high-frequency semiconductor device or the like that has low moisture resistance even in the transmission cavity4having small volume.

Although the substrate1and the ring member2are fixed to each other with the brazing material13such as solder in the above example, a conductive adhesive can be used for fixing the substrate1with the ring member2instead of the brazing material13. Moreover, although the ring member2and the cover3are fixed to each other with the brazing material8for welding in the above example, a conductive adhesive can be used for welding the ring member2to the cover3instead of the brazing material8. When the conductive adhesive is used, a portion at which the conductive adhesive is not applied is provided at a position shifted by λg/4 from the cavity center12on the boundary between the transmission cavity4and the reception cavity5to form the ventilation hole10. The cavity center can be located corresponding to a node of the resonance waveform in some specific sizes of cavities. If the cavity center is located corresponding to a node, it is allowable to locate the ventilation hole10at the center (shifted amount from the center is 0).

Second Embodiment

FIG. 10is a plan view of a configuration of a transceiver device according to a second embodiment of the present invention. While in the first embodiment, the ventilation hole10is arranged at a position shifted by λg/4 from the cavity center12, in the second embodiment, the ventilation hole10is arranged at a position shifted by (n×λg/2)+λg/4 (n: positive integer) as shown inFIG. 10. As described above, in the resonance waveform, the electric-field peaks (antinodes) appear at λg/2 intervals, and therefore, in the second embodiment, the ventilation hole10is arranged at a position shifted by (λg/4)+(λg/2)×n from the cavity center12.

As described above, in the second embodiment, the ventilation hole10is arranged at a position shifted by (λg/4)+(λg/2)×n from the cavity center12between the transmission cavity4and the reception cavity5. Therefore, it is possible to virtually increase the volume of the transmission cavity4that actually has small volume while maintaining the electrical isolation between the transmission cavity4and the reception cavity5, thereby increasing the water saturation amount of the transmission cavity4. As a result, it becomes possible to mount a high-frequency semiconductor device or the like that has low moisture resistance even in the transmission cavity4having small volume.

Third Embodiment

FIG. 11is a plan view of a configuration of a transceiver device according to a third embodiment of the present invention. The ventilation hole10is arranged only at a single position that is shifted by λg/4 from the cavity center12in the first embodiment, and the ventilation hole10is arranged at a single position that is shifted by λg/4 from the cavity center12in the second embodiment, as shown inFIG. 11. In the present embodiment, a plurality of ventilation holes is arranged at λg/2 intervals from the position that is shifted by λg/4 from the cavity center.

As described above, in the third embodiment, the ventilation holes are arranged between the transmission cavity4and the reception cavity5at λg/2 intervals from the position that is shifted by λg/4 from the cavity center12. Therefore, it is possible to virtually increase the volume of the transmission cavity4that actually has small volume while maintaining the electrical isolation between the transmission cavity4and the reception cavity5, thereby increasing the water saturation amount of the transmission cavity4. As a result, it becomes possible to mount a high-frequency semiconductor device or the like that has low moisture resistance even in the transmission cavity4having small volume.

Fourth Embodiment

FIG. 12is a plan view of a configuration of a transceiver device according to a fourth embodiment of the present invention. Although it is assumed that there are two cavities for the transmission cavity4and the reception cavity5in the first to the third embodiments, it is assumed that there are three or more cavities in the fourth embodiment. In the example the one transmission cavity4is arranged between two reception cavities5aand5b. Between the transmission cavity4and the reception cavity5a, a ventilation hole10asimilar to the one described above is formed, and between the transmission cavity4and the reception cavity5b, a ventilation hole10bsimilar to the one described above is formed. The ventilation holes10aand10bare arranged at positions shifted by λg/4 from the cavity center12, similarly to the first embodiment.

As described above, in the fourth embodiment, each of ventilation holes10aand10bare arranged at a position shifted by λg/4 from the cavity center12between three or more cavities. Therefore, it is possible to virtually increase the volume of a cavity that actually has small volume while maintaining the electrical isolation between the respective cavities, thereby increasing the water saturation amount of the cavity that has small volume. As a result, it becomes possible to mount a high-frequency semiconductor device or the like that has low moisture resistance even in the cavity having small volume.

INDUSTRIAL APPLICABILITY

As set forth hereinabove, a transceiver device according to the present invention is suitable as a transceiver device that is used in microwave band and millimeter-wave band.