JP5198327B2 - High frequency substrate, transmitter, receiver, transmitter / receiver, and radar device including high frequency substrate - Google Patents

Description

  The present invention relates to a high-frequency substrate for mounting a high-frequency element mainly used in a microwave band or a millimeter-wave band, and a transmitter, a receiver, a transceiver, and a radar apparatus including the high-frequency substrate.

  In recent years, research and development of wireless communication technologies typified by mobile phones and wireless local area networks (LANs) have been actively conducted. In the research and development of wireless communication, some transmission speeds of FTTH (Fiber to The Home) represented by optical communication achieve 100 Mbps or more.

  However, the transmission speed of wireless communication devices currently on the market is less than that of optical communication. In many wireless communication devices, microwaves are used as carrier waves, but microwaves have a low data transmission rate. For example, in high-definition video data transmission, high-capacity uncompressed video data with reduced image quality is suppressed. Is not suitable.

  Therefore, radio communication using electromagnetic waves having a frequency higher than that of microwaves, for example, quasi-millimeter waves and millimeter waves of 20 GHz or more, has been attracting attention as a means for transmitting a large amount of data, and research and development have been promoted. ing.

  In particular, in the 60 GHz band, a wide band is allocated for wireless communication, which is common throughout the world, and wireless communication using such 60 GHz band electromagnetic waves is now in practical use, and instead of optical fiber communication, It is used for communications and is becoming popular. In addition, as a means for supporting safe driving of automobiles, radar systems using millimeter wave electromagnetic waves have been installed in general passenger cars.

  In order to realize these wireless communication systems and radar systems, research and development of devices that process millimeter wave signals and millimeter wave circuits are underway. Typical transmission lines for millimeter wave circuits are microstrip lines, coplanar lines, and laminated waveguide lines. Among these, the laminated waveguide line has the lowest transmission loss in the millimeter wave band, no radiation, and a wide band.

  Therefore, in wiring design of a millimeter wave circuit, it is most preferable to use a laminated waveguide line from the viewpoint of suppressing loss, such as a microstrip line connected to a semiconductor element or a coplanar line connected to a semiconductor element. A conversion structure is known in which a microstrip line converted from a high-frequency transmission line is connected to a laminated waveguide line.

  The converter described in Patent Document 1 includes a dielectric substrate, a ground conductor pattern, a strip conductor pattern, a conductor pattern for a waveguide upper wall formed continuously with the strip conductor pattern, a ground conductor pattern, and a waveguide. A conductor for connecting to the conductor pattern for the upper wall of the tube, and the dielectric substrate, the ground conductor pattern, and the strip conductor pattern constitute a microstrip line, and the dielectric substrate and the waveguide upper wall A conductor waveguide, a ground conductor pattern, and a connecting conductor constitute a dielectric waveguide.

  By this converter, the microstrip line and the waveguide can be connected without using a ridge or a probe, and the impedance of the waveguide can be adjusted by adjusting the arrangement of the vias as the connection conductors. The high frequency signal can be propagated without causing large reflection.

  A bonding wire is used for connection between the semiconductor element for high-frequency signal processing and a transmission line such as a microstrip line. In high-frequency regions such as millimeter waves, the transmission characteristics are affected by the inductance component of the bonding wire, so that a matching circuit is provided on the transmission line side to improve the transmission characteristics.

JP 2002-208806 A

  However, in the converter described in Patent Document 1, the transmission characteristics of high-frequency signals are greatly affected by the size and shape of each conductor pattern and the arrangement position of the connecting conductor. When the dielectric substrate is displaced or the patterning accuracy is low, the conductor pattern size and shape change, which causes reflection of a high frequency signal in the converter, thereby degrading transmission characteristics.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a high-frequency substrate that can suppress deterioration of transmission characteristics due to manufacturing defects, a transmitter including the high-frequency substrate, and a receiver. It is providing a transmitter, a transceiver, and a radar apparatus.

The present invention provides a first dielectric substrate having a first dielectric layer, a pair of main conductor layers sandwiching the first dielectric layer, and a via-hole conductor group that electrically connects the pair of main conductor layers. A first dielectric substrate provided with a laminated waveguide line for propagating a high-frequency signal in a region of the first dielectric layer surrounded by the main conductor layer and the via-hole conductor group;
A second dielectric substrate stacked on the first dielectric substrate, having a mounting surface opposite to the surface on the first dielectric substrate side and being smaller than a relative dielectric constant of the first dielectric layer; A second dielectric layer having a relative dielectric constant; a high-frequency transmission line conductor formed on the mounting surface; and a conversion unit for electromagnetically coupling the high-frequency transmission line conductor and the laminated waveguide line. A high-frequency substrate comprising a second dielectric substrate.

The present invention also provides the high frequency substrate described above,
A transmitting element that is mounted on the mounting surface of the high-frequency substrate and connected to the high-frequency transmission line conductor, and outputs a high-frequency signal;
An antenna substrate bonded to a side of the first dielectric substrate opposite to the side on which the second dielectric substrate is laminated, and radiates the high-frequency signal connected to the laminated waveguide line A transmitter comprising an antenna substrate including an antenna.

The present invention also provides the high frequency substrate described above,
A receiving element that is mounted on the mounting surface of the high-frequency substrate and is connected to the high-frequency transmission line conductor and receives a high-frequency signal;
An antenna substrate joined to the opposite side of the first dielectric substrate to the side on which the second dielectric substrate is laminated, and captures the high-frequency signal connected to the laminated waveguide line An antenna substrate including an antenna.

The present invention also provides the high frequency substrate described above,
A transmitting element that is mounted on the mounting surface of the high-frequency substrate and connected to the high-frequency transmission line conductor, and outputs a high-frequency signal;
A branching device for branching the high-frequency signal output from the transmission element;
A transmitting antenna that radiates one of the high-frequency signals connected to the multilayered waveguide line and branched by the branching device;
A receiving antenna connected to the laminated waveguide and capturing a high-frequency signal;
The transceiver includes a mixer that mixes the other high-frequency signal branched by the branching unit and the high-frequency signal captured by the receiving antenna and outputs an intermediate frequency signal.

The present invention also includes the transceiver described above,
A radar apparatus comprising: a detector for detecting at least a distance or a relative velocity with respect to a detection target based on an intermediate frequency signal from the mixer.

According to the present invention, the high-frequency transmission line conductor formed on the mounting surface of the second dielectric substrate and the laminated waveguide line provided on the first dielectric substrate are electromagnetically coupled by the conversion unit, By converting the quasi-TEM mode, which is the transmission mode of the high-frequency transmission line conductor, and the TE mode, which is the transmission mode of the laminated waveguide line, electromagnetic coupling is efficiently performed in the transmission direction of the high-frequency signal. . As a result, coupling with extremely small reflection is possible, and a wide band transmission characteristic is realized.

Since the second dielectric layer of the second dielectric substrate provided with the conversion unit has a relative dielectric constant smaller than that of the first dielectric layer, it propagates through the high-frequency transmission line conductor formed on the mounting surface. The wavelength of the high frequency signal to be performed can be increased.

  As a result, even if the patterning accuracy of the high-frequency transmission line conductor is low and variations occur in the pattern shape and dimensions, the fluctuation amount of the dimensional tolerance with respect to the guide wavelength of the high-frequency signal propagating in the dielectric layer is small. Therefore, it is possible to suppress the deterioration of the desired high-frequency signal transmission characteristics.

  According to the transmitter, receiver and transmitter / receiver of the present invention, the transmitting element, the receiving element, the branching device, etc. are mounted on the second dielectric substrate and the first dielectric substrate is transmitted / received with respect to the above high-frequency substrate. For example, when a high-frequency signal processed by a transmitting element is transmitted to the antenna and radiated, or when a high-frequency signal captured by the antenna is transmitted to a receiving element, the transmission characteristics of the high-frequency signal are reduced. Since deterioration is suppressed, it is possible to realize a small size and good transmission / reception performance.

  Further, according to the radar apparatus of the present invention, a radar apparatus with high detection accuracy can be realized by using a transceiver in which deterioration of transmission characteristics of high-frequency signals is suppressed.

It is the schematic which shows the structure of the antenna module 2 provided with the high frequency board | substrate 1 which is one Embodiment of this invention. FIG. 4 is an enlarged view of a connection portion between a laminated waveguide line 5 and a conversion unit 6. FIG. 3 is a plan view of dielectric layers 31, 32, 33, and 34 developed for each layer and viewed from one surface side of the high-frequency substrate 1. It is the schematic which shows the structure of the antenna module 71 provided with the high frequency board | substrate 70 which is other embodiment of this invention.

  FIG. 1 is a schematic diagram showing a configuration of an antenna module 2 including a high-frequency substrate 1 according to an embodiment of the present invention.

  The antenna module 2 includes a high-frequency substrate 1 and an antenna substrate 3, and an MMIC (monolithic microwave integrated circuit) 4 is mounted on the surface of the high-frequency substrate 1 as an integrated circuit for high-frequency signal processing.

  The high-frequency substrate 1 uses a laminated waveguide line 5 and a conversion unit 6 to a laminated waveguide line for connection between high-frequency semiconductor devices such as the MMIC 4 and the antenna substrate 3 for transmission and reception. . The MMIC 4 and the conversion unit 6 to the laminated waveguide 5 are connected via the bonding wire 7 and the microstrip line 8, but a matching circuit such as a stub may be provided therebetween. Further, the connection between the MMIC 4 and the conversion unit 6 may be realized not by wire bonding but by flip chip connection using metal bumps, solder balls, or the like.

  The high frequency substrate 1 is bonded to the antenna substrate 3 on the surface 1b of the high frequency substrate 1 opposite to the mounting surface 1a on which the MMIC 4 is mounted.

  The high-frequency substrate 1 and the antenna substrate 3 are electromagnetically coupled by the connection port 5 a of the laminated waveguide 5 provided on the high-frequency substrate 1 and one end 9 a of the waveguide 9 provided on the antenna substrate 3. . The waveguide 9 provided on the antenna substrate 3 is realized by a hollow waveguide having a through-hole penetrating the antenna substrate 3 in the thickness direction. The other end 9b of the waveguide 9 is an opening that is opened to the back surface of the antenna substrate 3, and this opening serves as a slot antenna to radiate or receive a high frequency having a frequency corresponding to the opening size.

  When the MMIC 4 is a transmission MMIC, the antenna module 2 functions as a transmitter. The high-frequency signal output from the transmission MMIC 4 and transmitted through the laminated waveguide 5 through the bonding wire 7 and the converter 6 reaches the connection port 5a. The high-frequency signal output from the connection port 5a is transmitted through the waveguide 9 of the antenna substrate 3 and radiated from the slot antenna at the other end 9b.

  When the MMIC 4 is a receiving MMIC, the antenna module 2 functions as a receiver. The high frequency signal received by the slot antenna at the other end 9b of the waveguide 9 is transmitted through the waveguide 9 of the antenna substrate 3, and is transmitted through the laminated waveguide 5 through the connection port 5a. The high-frequency signal transmitted through the laminated waveguide 5 is input to the MMIC 4 through the conversion unit and the bonding wire 7.

  When the MMIC 4 is a transmission / reception MMIC, the antenna module 2 functions as a transceiver. The high-frequency signal as the transmission signal and the reception signal is transmitted through the laminated waveguide 5 provided on the high-frequency substrate 1 and the waveguide 9 provided on the antenna substrate 3 in the same manner as the transmitter and receiver described above. .

  A feature of the present invention is that the high-frequency substrate 1 is composed of a first dielectric substrate 10 and a second dielectric substrate 11, and the relative dielectric constants of the respective dielectrics constituting these dielectric substrates are different. It is.

  The first dielectric substrate 10 is provided with the laminated waveguide 5 and has a connection port 5 a with the antenna substrate 3. The second dielectric substrate 11 has a mounting surface 1 a of the MMIC 4 and is provided with a conversion unit 6 for connecting to the laminated waveguide 5.

  The laminated waveguide 5 is configured such that a dielectric layer is surrounded by two conductor layers and a via-hole conductor group that electrically connects them, and among the lines for transmitting a high-frequency signal, a dielectric A high-frequency signal is transmitted to the (waveguide).

  As described above, one end of the laminated waveguide 5 is the connection port 5 a to the antenna substrate 3, and the other end is the connection portion 5 b to the conversion unit 6.

  The conversion unit 6 includes a conversion conductor 12 provided on the mounting surface 1a, a portion of the dielectric on which the conversion conductor 12 is formed, a through conductor that connects to the conversion conductor 12 and penetrates the dielectric in the thickness direction, and a mounting surface. It is provided on the surface 1b opposite to 1a and is constituted by a ground conductor connected to the through conductor. The ground conductor is provided with an opening, and the opening is connected to the connection portion 5 b of the laminated waveguide 5.

  In the high-frequency substrate 1 of the present invention, the dielectric constant of the dielectric that constitutes the second dielectric substrate 11 having the mounting surface 1a and provided with the conversion unit 6 is set to be the first provided with the laminated waveguide 5. The relative dielectric constant of the dielectric constituting the dielectric substrate 10 is made smaller.

  By reducing the dielectric constant of the dielectric, the wavelength of the high-frequency signal propagating through the planar wiring such as the microstrip line 8 and the matching circuit provided on the mounting surface 1a of the second dielectric substrate 11 can be increased. .

  As a result, the patterning accuracy of planar wiring is low, and even if the wiring shape and dimensions vary, the amount of variation in dimensional tolerance with respect to the guide wavelength of the high-frequency signal propagating in the dielectric layer is reduced. Therefore, it is possible to suppress the deterioration of the transmission characteristics of a desired high-frequency signal. In addition, when a matching circuit for matching the semiconductor element and the bonding wire connecting the planar circuit is provided, it is possible to suppress deterioration in transmission characteristics of the matching circuit.

The laminated waveguide line 5 and the conversion unit 6 will be described in detail.
FIG. 2 is an enlarged view of a connection portion between the laminated waveguide 5 and the converter 6. 2A is a plan view, FIG. 2B is a perspective view seen from the layer direction, and FIG. 3C is a cross-sectional view.

  The high-frequency substrate 1 includes a first dielectric substrate 10 and a second dielectric substrate 11, and these dielectric substrates are formed by laminating one or a plurality of dielectric layers, and a conductor between these dielectric layers. A layer is provided to form an inner layer wiring.

  For example, in the present embodiment, the second dielectric substrate 11 has one dielectric layer 31, and the first dielectric substrate 10 has three dielectric layers 32, 33, and 34. Are stacked in this order from the surface side of the high-frequency substrate 1 on which the MMIC is mounted. The dielectric layer 31 and the dielectric are formed so that the relative dielectric constant of the dielectric layer 31 as the second dielectric layer is smaller than the relative dielectric constant of the dielectric layers 32, 33, and 34 as the first dielectric layer. The layers 32, 33, and 34 are different in material used.

  The high frequency substrate 1 includes a dielectric layer 31 including the mounting surface 1 a of the second dielectric substrate 11, a microstrip line 8 formed on the dielectric layer 31, and a dielectric layer of the first dielectric substrate 10. A first laminated waveguide sub-line portion 21 formed including a dielectric layer 32 adjacent to the dielectric layer 31 and connected to the microstrip line 8 via the converter 6, and a first dielectric substrate Among the 10 dielectric layers, the second laminated waveguide sub-line portion 22 is formed to include the dielectric layers 31, 32, and 33 and is connected to the first laminated waveguide sub-line portion 21; Of the dielectric layers of the first dielectric substrate 10, the third laminated type is formed to include the dielectric layers 31, 32, 33, and 34 and is connected to the second laminated waveguide sub-line portion 22. Of the dielectric layers of the waveguide sub-line portion 23 and the first dielectric substrate 10, the dielectric layers 33 and 34 are included. Made, the laminated waveguide main line 24 which connects the third laminated waveguide sub-line part 23 is formed. The first laminated waveguide sub-line portion 21, the second laminated waveguide sub-line portion 22, and the third laminated waveguide sub-line portion 23 are composed of the microstrip line 8 and the laminated waveguide. The main line portion 24 is connected to the main line portion 24 with low loss, and is configured such that the lower main conductor layer approaches the conversion conductor 12 as it approaches the microstrip line 8 from the laminated waveguide main line portion 24. ing.

  The microstrip line 8 includes a strip conductor 8a and a ground (ground) conductor 8b that are opposed to each other with a dielectric layer 31 constituting the second dielectric substrate 11 sandwiched in the thickness direction.

  The conversion conductor 12 that constitutes a connection portion between the microstrip line 8 and the laminated waveguide line 5 and is provided on the surface of the second dielectric substrate 11 includes the first laminated waveguide sub-line portion 21, the first Among the main conductor layers of the two laminated waveguide sub-line portions 22 and the laminated waveguide main line portion 23, the upper main conductor layers 211, 221, and 231 are provided on the surface of the high-frequency substrate 1. These upper main conductor layers 211, 221, and 231 are integrally formed.

  The width direction dimension W with respect to the signal transmission direction of the conversion conductor 12 is the same as the width direction dimension of the main conductor layer, and may be set as appropriate depending on the frequency of the high-frequency signal to be transmitted. It is set in consideration of the cut-off frequency. For example, when the frequency of the high-frequency signal to be transmitted is 76.5 GHz, W = 1.15 mm, and the cutoff frequency is set at about 43 GHz.

  Also, the signal transmission direction ends of the lower main conductor layers 212, 222, and 232 are provided by being shifted in the signal transmission direction by 1/4 of the wavelength λ of the transmission signal. The length direction dimension L parallel to the signal transmission direction of the conversion conductor 12 is set to 3λ / 4 so as to cover the lower main conductor layers 212, 222, and 232 when viewed in plan. For example, when the frequency of the high-frequency signal to be transmitted is 70 to 85 GHz, L = 0.9 mm.

  The width direction dimension W and the length direction dimension L of the conversion conductor 12 are the minimum necessary dimensions for the conversion unit 6, and the conversion conductor 12 may be formed so that the width direction dimension becomes larger on both sides. The lengthwise dimension may be formed so as to extend toward the side opposite to the connection portion with the strip conductor 8a.

  The laminated waveguide 5 and the converter 6 are configured to include via-hole conductor groups 41 and 42 together with the pair of conductor layers (upper main conductor layer and lower main conductor layer) as described above.

  The via-hole conductor groups 41 and 42 are signals having an interval equal to or shorter than the cutoff wavelength of the high-frequency signal transmitted through the multilayered waveguide line 5 and the conversion unit 6 (for example, an interval of less than half the wavelength of the transmitted high-frequency signal). Arranged along the transmission direction, the laminated waveguide 5 forms an electrical side wall, and the side wall and a pair of conductor layers constitute a laminated waveguide.

  In the via-hole conductor groups 41 and 42 for forming the side walls, when the interval between adjacent via-hole conductors is larger than the cutoff wavelength of the high-frequency signal to be transmitted, the electromagnetic wave fed to the laminated waveguide is transmitted between the via-hole conductor and the via-hole conductor. Leaks from the gap, and does not propagate along the laminated waveguide formed by the side wall and the pair of main conductor layers. On the other hand, in the side wall forming via hole conductor groups 41 and 42, when the interval between adjacent via hole conductors is equal to or less than the cutoff wavelength, the electromagnetic wave is reflected without leaking from the gap between the via hole conductor and the laminated waveguide. Propagated in the signal transmission direction of the tube line 5.

  In the via hole conductors constituting the side wall forming via hole conductor groups 41 and 42, it is preferable that the interval between adjacent via hole conductors is set at a constant interval. , Can be set as appropriate within the range.

  Further, a side wall forming via hole conductor group is provided outside the two rows of side wall forming via hole conductor groups 41 and 42 forming the laminated waveguide 5, and a pseudo side wall by the side wall forming via hole conductor group is provided. By forming double or triple in the width direction with respect to the transmission direction, leakage of electromagnetic waves can be more effectively prevented.

  With reference to FIG. 3, it demonstrates concretely for every dielectric material layer. FIGS. 3A to 3D are plan views of the dielectric layers 31, 32, 33, and 34 developed for each layer and viewed from one surface side of the high-frequency substrate 1. FIG. 3E is a plan view of the dielectric layer 34 viewed from the other surface side.

  As shown in FIG. 3A, on one surface of the dielectric layer 31 constituting the second dielectric substrate 11, the strip conductor 8a and the upper main conductor layers 211, 211, 231 (conversion) connected thereto are provided. A conductor 12) is formed. In addition, in the dielectric layer 31, two rows of via-hole conductor groups 41 and 42 for forming side walls are formed as through conductors.

  Further, the end portion of the conversion conductor 12 and the end portion of the laminated waveguide main line portion 24 are arranged so as to overlap each other when viewed from one surface side. FIG. Boundary wall forming via-hole conductor group 43 consisting of via-hole conductors that electrically connect the end of 12 and the end of the laminated waveguide main line portion 24 cut off the transmission signal in a direction perpendicular to the signal transmission direction. Arranged inside the dielectric layer 31 at intervals equal to or shorter than the wavelength, the leakage of high-frequency signals from this boundary is prevented. The two via hole conductors at both ends of the boundary wall forming via hole conductor group 43 are shared with the side wall forming via hole conductor groups 41 and 42.

  As shown in FIG. 3B, the ground conductor 8 b and the sub conductor layer 51 constituting the microstrip line 8 are integrally formed on the surface of the dielectric layer 32 constituting the first dielectric substrate 10. . In addition, two rows of side wall forming via-hole conductor groups 41 and 42 are formed inside the dielectric layer 32.

  Further, the end portion of the ground conductor 8b and the end portion of the lower main conductor layer 212 are arranged so as to overlap when viewed from one surface side, and the end portion of the ground conductor 8b and the end portion of the lower main conductor layer 212 are disposed. Boundary wall forming via-hole conductor group 43 consisting of via-hole conductors that are electrically connected to each other are arranged in a direction perpendicular to the signal transmission direction at intervals equal to or less than the signal cutoff wavelength, and leakage of high-frequency signals from this boundary is prevented. A boundary wall is formed to prevent this. The two via hole conductors at both ends in the arrangement of the via hole conductor group 43 are shared with the via hole conductor groups 41 and 42 for forming the side walls.

  As shown in FIG. 3C, the lower main conductor layer 212, the sub conductor layer 52, and the laminated waveguide main line portion 24 are formed on the surface of the dielectric layer 33 constituting the first dielectric substrate 10. The upper main conductor layer 61 is electrically connected and formed integrally. In addition, two rows of side wall forming via-hole conductor groups 41 and 42 are formed inside the dielectric layer 33.

  Further, the end of the lower main conductor layer 212 and the end of the lower main conductor layer 222 are arranged so as to overlap when viewed from one surface side, and the end of the lower main conductor layer 212 and the lower side A boundary wall forming via-hole conductor group 43 made of via-hole conductors that electrically connect the ends of the main conductor layer 222 is arranged in a direction perpendicular to the signal transmission direction at intervals equal to or smaller than the signal cutoff wavelength. A boundary wall is formed to prevent leakage of high frequency signals. The two via hole conductors at both ends in the arrangement of the via hole conductor group 43 are shared with the via hole conductor groups 41 and 42 for forming the side walls.

  As shown in FIG. 3D, a lower main conductor layer 222 and a sub conductor layer 53 are formed on the surface of the dielectric layer 34 constituting the first dielectric substrate 10. In addition, two rows of side wall forming via-hole conductor groups 41 and 42 are formed inside the dielectric layer 34.

  Further, the end of the lower main conductor layer 222 and the end of the lower main conductor layer 232 are arranged so as to overlap when viewed from one surface side, and the end of the lower main conductor layer 222 and the lower side A boundary wall forming via-hole conductor group 43 made of via-hole conductors that electrically connect the ends of the main conductor layer 232 is arranged in a direction perpendicular to the signal transmission direction at intervals equal to or smaller than the signal cutoff wavelength. A boundary wall is formed to prevent leakage of high frequency signals. The two via hole conductors at both ends in the arrangement of the via hole conductor group 43 are shared with the via hole conductor groups 41 and 42 for forming the side walls.

  As shown in FIG. 3E, the lower main conductor layer 232 and the lower main conductor layer 62 constituting the laminated waveguide main line portion 24 are formed on the back surface of the dielectric layer 34. Although not shown in FIG. 3E, a boundary wall forming via hole conductor group 43 shown in FIG. 3D is connected to the end of the lower main conductor layer 232. Also, sidewall forming via-hole conductor groups 41 and 42 shown in FIG. 3D are connected to the lower main conductor layer 62 constituting the laminated waveguide main line portion 24.

  Further, when the dielectric layer constituting the laminated waveguide line is composed of a plurality of layers like the first dielectric substrate 10, it is preferable to provide a sub conductor layer in parallel with the main conductor layer between the dielectric layers. The sub conductor layer is a strip-like conductor layer that belongs to the same row and electrically connects each via-hole conductor group penetrating the same dielectric layer for each row and extends in the arrangement direction of the via-hole conductor group.

  Such sub-conductor layers correspond to the conductor layers 51, 52 and 53 in FIG. 3, and side walls formed in a lattice shape are obtained by the via-hole conductor group and the sub-conductor layer. Electromagnetic leakage can be shielded. Further, the sub conductor layer also functions as a large land of the via hole conductor, and can suppress poor connection in the thickness direction of the via hole conductor caused by the stacking deviation. If a poor connection in the thickness direction of the via-hole conductor occurs, electromagnetic leakage is likely to occur at the poor connection portion and transmission loss increases. However, this can be prevented by providing a sub-conductor layer.

  With such a configuration of the conversion unit 6, the transmission mode of the high-frequency signal output from the MMIC 4 or the high-frequency signal input to the MMIC 4 is different from the quasi-TEM mode that is the transmission mode of the microstrip line 8, and the stacked type transmission mode. The TE mode, which is the transmission mode of the wave guide line 5, is converted to each other, and a broadband, low-loss signal transmission can be realized.

  As described above, the relative dielectric constant of the dielectric constituting the second dielectric substrate 11 provided with the conversion unit 6 is equal to that of the dielectric constituting the first dielectric substrate 10 provided with the laminated waveguide 5. Any material may be used as long as it is smaller than the relative dielectric constant. Preferably, the relative dielectric constant of the dielectric constituting the second dielectric substrate 11 is not more than 3/4 times, more preferably 1/2 times the relative dielectric constant of the dielectric constituting the first dielectric substrate 10. It should be: Thereby, deterioration of the transmission characteristic of a high frequency signal can be suppressed effectively.

  As dielectrics constituting the first dielectric substrate 10 and the second dielectric substrate 11, ceramic materials such as alumina, aluminum nitride, and glass ceramics, polyimide, glass epoxy, PTFE (polytetrafluoroethylene), liquid crystal polymer, fluorine An organic material such as a resin or a fluorine glass resin can be used.

  When the dielectrics constituting the first dielectric substrate 10 and the second dielectric substrate 11 are both ceramic materials, for example, the relative dielectric constant is 9 to 10 as the dielectric constituting the first dielectric substrate 10. It is preferable to use a glass ceramic having a relative dielectric constant of about 2 to 4 as the dielectric constituting the second dielectric substrate 11.

  When the dielectrics constituting the first dielectric substrate 10 and the second dielectric substrate 11 are both ceramic materials, the high-frequency substrate 1 can be manufactured as follows.

  For the first dielectric substrate 10, a suitable organic solvent / solvent is added to the raw material powder of the alumina ceramics to form a mud, and this is applied to the sheet by using a conventionally known doctor blade method, calendar roll method, or the like. A plurality of ceramic green sheets are obtained by forming a shape, and a ceramic green sheet is obtained by adding and mixing an appropriate organic solvent / solvent to the glass ceramic raw material powder for the second dielectric substrate 11.

  Thereafter, each ceramic green sheet is appropriately punched, filled with a conductive paste into a via hole, laminated with a printed wiring pattern and solid pattern, and baked, whereby the first dielectric substrate 10 and The second dielectric substrate 11, that is, the high frequency substrate 1 is manufactured.

  As the strip conductor, the ground conductor, and the pair of main conductor layers, for example, when the dielectric layer is made of an alumina ceramic, an oxide such as alumina, silica, magnesia, etc. suitable for metal powder such as tungsten and molybdenum, A conductor paste mixed with an organic solvent and a solvent is printed on the ceramic green sheet by a thick film printing method, and then simultaneously fired at a high temperature of about 1600 ° C. to form a thickness of 10 to 15 μm or more. . As the metal powder, copper, gold and silver are suitable for glass ceramics, and tungsten and molybdenum are suitable for alumina ceramics and aluminum nitride ceramics. The main conductor layer has a thickness of about 5 to 50 μm.

  As described above, when different types of materials are used as the dielectrics constituting the first dielectric substrate 10 and the second dielectric substrate 11, the respective sintering temperatures are different.

  In the case of glass ceramics, the sintering temperature is from 850 to 1000 ° C., and in the case of alumina, from 1500 to 1700 ° C., the green sheet laminate is first fired at the sintering temperature of the glass ceramics. At this time, since the alumina green sheet is not sintered, shrinkage does not occur, and when the glass ceramic is sintered, shrinkage of the glass ceramic is suppressed by the alumina green sheet. Thereby, restraint baking of glass ceramics becomes possible.

  Further, after the glass ceramic is sintered, it is fired at the sintering temperature of alumina. At this time, since the glass ceramic is already sintered, the glass ceramic does not shrink during the sintering of alumina. Therefore, shrinkage of alumina is suppressed by the glass ceramics when the alumina is sintered. Thereby, restraint baking of alumina becomes possible.

  As described above, restraint firing is possible without separately using a jig for restraint firing, and the high-frequency substrate 1 can be manufactured with high dimensional accuracy.

  Further, when the dielectric constituting the first dielectric substrate 10 is a ceramic material and the dielectric constituting the second dielectric substrate 11 is a resin material, for example, the first dielectric substrate 10 is configured. As the dielectric material, alumina having a relative dielectric constant of about 9 to 10 is used, and as the dielectric material constituting the second dielectric substrate 11, polyimide, glass epoxy, PTFE, liquid crystal polymer, fluororesin having a relative dielectric constant of about 2 to 4 Fluorine glass resin is preferably used.

  In the case of such a configuration, the first dielectric substrate 10 and the second dielectric substrate 11 are separately manufactured, and the high-frequency substrate 1 can be manufactured by bonding them with a conductive adhesive or the like.

  Since the shift between the laminated waveguide line 5 and the conversion unit 6 has a great influence on the transmission characteristics, the first dielectric substrate 10 and the second dielectric substrate 11 can be manufactured separately. These bonding steps can be performed with high accuracy by applying an image recognition technique or the like, and a shift between the laminated waveguide 5 and the conversion unit 6 can be suppressed.

  Furthermore, after the MMIC 4 is mounted on the second dielectric substrate 11 in advance, the second dielectric substrate 11 on which the MMIC 4 has been mounted and the first dielectric substrate 10 can be bonded together.

  FIG. 4 is a schematic diagram showing a configuration of an antenna module 71 including a high-frequency substrate 70 according to another embodiment of the present invention.

  The difference in configuration between the antenna module 71 of the present embodiment and the antenna module 2 shown in FIG. 1 is that the protective cap 72 of the MMIC 4 is provided in the present embodiment, and the second dielectric substrate 73 is It is to be provided with a size that can be accommodated in the internal space.

  In addition, about the same structure as the antenna module 2 shown in FIG. 1, the same referential mark is attached | subjected and description is abbreviate | omitted.

  The purpose of providing the protective cap 72 is to prevent unwanted electromagnetic waves from being coupled to the signal line from entering the signal line and preventing noise from being mixed into the signal, and to prevent adverse effects on other devices by radiating the electromagnetic waves to the outside. To do. The protective cap 72 is preferably formed by a metal casing made of a metal such as aluminum. By using the protective cap 72 as a metal casing, the electromagnetic wave shielding property is high and the heat radiation property is improved. Moreover, not only a metal housing | casing but the thing which gave metal plating and metal metallization to the inner surface of a resin housing | casing or a ceramic housing | casing may be used.

  A bias wiring 74 for driving the MMIC 4 is formed inside the first dielectric substrate 10 and connected to a connection pad on the back surface of the second dielectric substrate 73.

  Further, as another embodiment of the present invention, a transceiver and a radar apparatus including the high-frequency substrate 1 can be realized.

  The transceiver is composed of a high-frequency substrate 1, a transmission MMIC 4 mounted on the second dielectric substrate 11, a branching device that branches a high-frequency signal output from the MMIC 4, and a transmission antenna provided on the antenna substrate 3. A transmission antenna that is connected to the type waveguide line 5 and radiates one high frequency signal branched by a branching device, and a high frequency signal that is connected to the laminated type waveguide line 5 and provided on the antenna substrate 3 is captured. A receiving antenna and a mixer that mixes the other high-frequency signal branched by the branching device and the high-frequency signal captured by the receiving antenna to output an intermediate frequency signal.

  Further, the radar apparatus includes the above-described transmitter / receiver and a detector that detects at least the distance or relative speed with respect to the detection target object based on the intermediate frequency signal from the mixer.

  Since the transmitter / receiver of the present invention uses the high-frequency substrate 1, deterioration of the transmission characteristics of the high-frequency signal can be suppressed, so that it is possible to realize a small and favorable transmission / reception performance.

  In addition, the radar apparatus of the present invention can improve detection accuracy by using a transmitter / receiver in which deterioration of transmission characteristics of high-frequency signals is suppressed.

  In addition, this invention is not limited to the said Example. The converter 6 for electromagnetically coupling the high-frequency transmission line conductor and the laminated waveguide line is not limited to the above structure, and a connection structure between a known high-frequency transmission line conductor and the laminated waveguide line can be applied.

DESCRIPTION OF SYMBOLS 1 High frequency board 2 Antenna module 3 Antenna board 4 MMIC (monolithic microwave integrated circuit)
5 Laminated Waveguide Line 6 Conversion Unit 10 First Dielectric Substrate 11 Second Dielectric Substrate

Claims (6)

A first dielectric substrate having a first dielectric layer, a pair of main conductor layers sandwiching the first dielectric layer, and a via-hole conductor group electrically connecting the pair of main conductor layers, A first dielectric substrate provided with a laminated waveguide line for propagating a high-frequency signal in a region of the first dielectric layer surrounded by the main conductor layer and the via-hole conductor group;
A second dielectric substrate stacked on the first dielectric substrate, having a mounting surface opposite to the surface on the first dielectric substrate side and being smaller than a relative dielectric constant of the first dielectric layer; A second dielectric layer having a relative dielectric constant; a high-frequency transmission line conductor formed on the mounting surface; and a conversion unit for electromagnetically coupling the high-frequency transmission line conductor and the laminated waveguide line. A high frequency substrate comprising: a second dielectric substrate. The high-frequency transmission line conductor is a strip conductor constituting a strip line,
The high-frequency substrate according to claim 1, wherein the conversion unit includes a conversion conductor formed on the mounting surface and electrically connected to the strip conductor. The high-frequency substrate according to claim 1 or 2,
A transmitting element that is mounted on the mounting surface of the high-frequency substrate and connected to the high-frequency transmission line conductor, and outputs a high-frequency signal;
An antenna substrate bonded to a side of the first dielectric substrate opposite to the side on which the second dielectric substrate is laminated, and radiates the high-frequency signal connected to the laminated waveguide line A transmitter comprising: an antenna substrate including an antenna. The high-frequency substrate according to claim 1 or 2,
A receiving element that is mounted on the mounting surface of the high-frequency substrate and is connected to the high-frequency transmission line conductor and receives a high-frequency signal;
An antenna substrate joined to the opposite side of the first dielectric substrate to the side on which the second dielectric substrate is laminated, and captures the high-frequency signal connected to the laminated waveguide line A receiver comprising an antenna substrate including an antenna. The high-frequency substrate according to claim 1 or 2,
A transmitting element that is mounted on the mounting surface of the high-frequency substrate and connected to the high-frequency transmission line conductor, and outputs a high-frequency signal;
A branching device for branching the high-frequency signal output from the transmission element;
A transmitting antenna that radiates one of the high-frequency signals connected to the multilayered waveguide line and branched by the branching device;
A receiving antenna connected to the laminated waveguide and capturing a high-frequency signal;
A transceiver comprising: a mixer that mixes the other high-frequency signal branched by the branching device and the high-frequency signal captured by the receiving antenna to output an intermediate frequency signal. The transceiver according to claim 5 ;
A radar apparatus comprising: a detector for detecting at least a distance or a relative velocity with respect to a detection target based on an intermediate frequency signal from the mixer.

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