JP2011139244A - High frequency module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem with a high frequency module for transmission and reception comprising a dielectric multilayer substrate and a semiconductor device for transmission and reception, wherein a frequency is changed due to temperature to deviate from a desired frequency band. <P>SOLUTION: A resistor whose resistance value is changed due to temperature and the intermediate voltage of a series circuit made of the resistor are connected to a voltage terminal for frequency control formed in the semiconductor device, and a frequency fluctuation due to the temperature is suppressed by controlling a frequency with the intermediate voltage that changes in following a change in the temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-frequency module for mounting a high-frequency element mainly used in a microwave band and a millimeter wave band.

  In recent years, research and development of wireless communication technologies typified by mobile phones and wireless LANs have been actively conducted. The wireless communication devices currently on the market use microwaves as carrier waves, but the data transmission speed of microwaves is slow. For example, high-capacity uncompressed video data can be transferred with reduced image quality degradation. Is not suitable.

  Therefore, wireless 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 attracted attention as a means for transmitting large-capacity data, and research and development have been promoted. In particular, in the 60 GHz band, a wide band is allocated for communication in common throughout the world, and it is desired to develop a wireless communication technology using such an electromagnetic wave in the 60 GHz band.

  High-frequency boards used in these communication systems are required to have a wider bandwidth, smaller size, more functions, unwanted noise resistance, and lower cost. To meet these demands, multilayer boards have been used. It was. In particular, a multilayer wiring board using a ceramic, which is a high dielectric constant material that can be miniaturized, as a dielectric layer has realized the multilayering of the board by using a simultaneous firing technique with a wiring metal. A plurality of high-frequency devices are mounted on such a high-frequency substrate, and operate as a high-frequency circuit by being connected to the transmission line via the high-frequency device and the conversion unit.

  Here, one of the performances required for the high-frequency substrate is a stable transmission performance under the usage environment. Since the high frequency device has temperature characteristics, the frequency of the high frequency device has been stabilized using a TCXO (temperature compensation capacitor) or the like.

JP 2001-351928 A

  However, the conventional technology has not been able to reduce the cost sufficiently, and a frequency stabilization technology that can be realized at low cost has been demanded.

  Accordingly, an object of the present invention is to provide a high-frequency module in which frequency fluctuation due to temperature of the high-frequency element is suppressed.

  The high-frequency module according to the present invention includes a substrate, a high-frequency element disposed on the substrate, and a grounding via hole that is formed immediately below a region where the high-frequency element is mounted on the substrate and connects the high-frequency element to a ground potential. A conductor group, a dielectric layer, a pair of main conductor layers sandwiching the dielectric layer, and a pair of main conductor layers penetrating the first dielectric layer and disposed between the pair of main conductor layers are disposed inside the substrate. A plurality of via-hole conductors connected to each other, and a side wall conductor group disposed at an interval of less than half the wavelength of the high-frequency signal transmitted by the plurality of via-hole conductors, and the laminated waveguide on the substrate A conversion unit for deriving the high-frequency signal, a connection body that connects the high-frequency element and the laminated waveguide through the conversion unit, the high-frequency element, the connection body, and the conversion unit, A storage space for storing the inside A temperature compensation circuit for correcting a frequency variation due to the temperature of the high-frequency element by a resistance value corresponding to a temperature obtained from the temperature-sensitive resistor, and the temperature-sensitive resistor is disposed on the substrate. It is arranged and connected to the ground via-hole conductor group inside the substrate.

  According to the high frequency module of the present invention, it is possible to compensate for frequency fluctuations of the high frequency device by a temperature compensation circuit having a simple configuration. In addition, the ground via hole conductor group formed immediately below the high-frequency element can dissipate heat generated in the high-frequency element and connect the temperature-sensitive resistor to the ground potential. And a part of the configuration of the temperature compensation circuit can be shared, and the frequency variation of the high-frequency element can be compensated with a simple configuration.

It is sectional drawing which shows an example of embodiment of the high frequency module of this invention. It is a circuit diagram which shows a temperature compensation circuit. It is a diagram which shows the temperature characteristic of the high frequency module of this invention. (A), (b) is the top view and sectional drawing which show the structure of a conversion part and a laminated waveguide, respectively. (A)-(e) is a top view for every dielectric material layer which shows the structure of a conversion part and a laminated waveguide, respectively.

  Hereinafter, the high-frequency module of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same location in drawing, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a high-frequency module according to the present invention.

  1 is a substrate, 2 is a high-frequency element, 3 is a grounding via-hole conductor group, 4 is a laminated waveguide, 13 is a converter, 6 is a connection body, 7 is a protective member, 8 is a temperature-sensitive resistor, and 9 is This is a transmission line for connecting the grounding via-hole conductor group 3 and the temperature-sensitive resistor 8 inside the substrate 1.

  The substrate 1 is configured by laminating a plurality of dielectric layers, providing a conductor layer between these dielectric layers, and forming an inner layer wiring. A high frequency element 2 is disposed on the first main surface 1 a of the substrate 1. For the high-frequency element 2, for example, an MMIC made of a compound semiconductor such as SiGe can be used. Such a high-frequency element 2 may be appropriately selected from a transmission / reception function integrated type, a transmission function type, a reception function type, and the like.

  A ground via-hole conductor group 3 penetrating to the second main surface 1b of the substrate 1 is formed immediately below the region of the first main surface 1a where the high-frequency element 2 is mounted. This grounding via-hole conductor group 3 is connected to the ground potential and grounds the high-frequency element 2 and effectively radiates heat from the high-frequency element 2.

  One port of the high-frequency element 2 is connected to the laminated waveguide 4 via the connection body 6 and the conversion unit 13. In this example, the connection body 6 includes a bonding wire 11 and a microstrip line 12 connected to the bonding wire 11.

  The conversion unit 13 is a part that converts the transmission mode between the TEM mode that transmits the bonding wire 11 and the microstrip line 12 and the TE mode or TM mode that transmits the laminated waveguide 4. It will be described later. In connecting the laminated waveguide 4 and the high-frequency element 2, the bonding wire 11 and the converter 5 may be directly connected, or may be connected via the microstrip line 12 as in this embodiment. Good. The microstrip line 12 may be provided with a stub for impedance matching.

  The laminated waveguide 4 is disposed inside the substrate 1 and is spaced from the first main surface 1a of the substrate 1 to the second main surface 1b side. Although the configuration will be described later, a dielectric layer, a pair of main conductor layers sandwiching the dielectric layer in the thickness direction, and a plurality of electrical connections between the pair of main conductor layers that penetrate the dielectric layer. It is comprised with the side wall conductor group arrange | positioned with the space | interval less than 1/2 of the cutoff wavelength of the high frequency signal which a via-hole conductor transmits. An input / output unit 10 is formed on the tube wall of the laminated waveguide 4 on the second main surface 1b side. The input / output unit 10 includes a slot antenna, a patch antenna, and the like.

  With this configuration, a high frequency signal can be transmitted between the high frequency element 2 and the input / output unit 10.

  A protective member 7 is disposed on the first main surface 1a. The protective member 7 has a cavity for accommodating the high-frequency element 2 therein, and can be hermetically sealed by being joined to the first main surface 1a. The protective member 7 is preferably formed of a metal casing made of a metal such as aluminum. By using a metal casing, the shielding property of electromagnetic waves is high and the heat dissipation is improved. Moreover, not only a metal housing but a housing made of an insulating material such as resin or ceramic may be used. Such a protective member 7 is arranged so that only the high-frequency element 2, the connection body 6, and a part of the conversion portion 5 exposed on the first main surface 1 a of the substrate 1 are accommodated in the accommodation space. Thereby, since the size of the accommodation space can be reduced, the resonance frequency inside the accommodation space can be set to a high region outside the operating frequency range of the high frequency element 2.

  A temperature compensation circuit is connected to the high frequency element 2. For example, as shown in the circuit diagram of FIG. 2, the temperature compensation circuit includes a resistor R and a temperature sensitive resistor Rth connected in series from the external bias terminal Vcc to the ground potential, and the resistor R and the temperature sensitive type are connected. An output unit Vt for outputting an intermediate voltage is connected between the resistor Rth and the resistor Rth.

  The external bias terminal Vcc is formed of, for example, a conductive layer (not shown) formed outside the region where the protective member 7 is disposed on the first main surface 1a of the substrate 1. The resistor R is constituted by, for example, a chip resistor (not shown) arranged outside the region where the protective member 7 is arranged on the first main surface 1a of the substrate 1.

  The temperature sensitive resistor Rth is constituted by a temperature sensitive resistor 8 disposed outside the region where the protective member 7 is disposed on the first main surface 1a of the substrate 1. And these are connected by the conductive layer formed on the 1st main surface 1a of the board | substrate 1, and this and the high frequency element 2 are connected to the conductive layer which connects a chip resistor and the temperature sensitive resistor 8. FIG. The output unit is connected. The temperature-sensitive resistor 8 has a resistance value that varies depending on the temperature. For example, a linear positive temperature resistor may be used. The temperature-sensitive resistor 8 is connected to the ground via-hole conductor group 3 by the transmission line 9 formed inside the substrate 1 and is connected to the ground potential together with the high-frequency element 2.

  The temperature compensation circuit that connects the intermediate voltage of the series circuit composed of the temperature-sensitive resistor 8 and the resistor R, the resistance value of which varies depending on the temperature, to the frequency control voltage terminal of the high-frequency element 2 tracks the temperature change. The operating frequency of the high-frequency element 2 is controlled by the intermediate voltage that changes. Thereby, it is possible to provide a high-frequency module having good temperature characteristics in which frequency fluctuation due to temperature is suppressed. Further, since the temperature compensation circuit has such a simple configuration and a part of the configuration is shared with the ground via-hole conductor group 3, the cost can be reduced.

  Further, the temperature-sensitive resistor 8 is grounded by the transmission line 9 formed inside the substrate 1 and the grounding via-hole conductor group 3 also formed inside the substrate 1. With such a configuration, all the paths for grounding the temperature-sensitive resistor 8 are accommodated inside the substrate 1, and the path for grounding is exposed on the surface (1a) of the substrate 1. Compared to the case, since it does not come into contact with the external environment, the influence of the temperature of the external environment can be suppressed, and the temperature-sensitive resistor 8 can be operated stably. That is, the temperature sensitive resistor 8 is exposed and arranged on the first main surface 1a of the substrate 1 in the same manner as the high frequency element 2 in order to realize temperature correction under the same environment as the high frequency element 2. By forming the line portion constituting the path for grounding inside the substrate 1, the influence of the external environment temperature of the transmission line that cannot be temperature-corrected can be suppressed, and temperature compensation can be performed more precisely. It will be a thing.

  The high frequency module is configured as described above. FIG. 3 shows the result of measuring the operating frequency variation with respect to the environmental temperature of the high-frequency module. In FIG. 3, the horizontal axis represents the environmental temperature (unit: ° C.), the vertical axis represents the frequency fluctuation amount (unit: GHz), and the value obtained by the high-frequency module of the present invention is indicated by a rhombus and does not have a temperature compensation circuit The values from the high-frequency module are plotted with square signs. As is clear from FIG. 3, it was confirmed that the amount of frequency fluctuation due to temperature can be significantly suppressed by the high frequency module of the present invention.

  Next, the structure of the laminated waveguide 4 and the conversion part 13 which comprise the high frequency module of this invention is explained in full detail.

  4A and 4B are a plan view and a cross-sectional view showing the configuration of the conversion unit and the laminated waveguide, respectively.

  The high frequency substrate 1 is configured by laminating a plurality of dielectric layers. For example, dielectric layers 31, 32, 33, and 34 are laminated in order from the first main surface 1a side, The microstrip line 12 is formed on the dielectric layer 31 including the first main surface 1a.

  The microstrip line 12 includes a strip conductor 12b and a ground conductor 12c that are opposed to each other with the dielectric layer 31 in between.

  The converter 13 preferably changes the impedance between the microstrip line 12 and the laminated waveguide 4 gradually or stepwise from the viewpoint of reducing transmission loss. As such a conversion part, there exists a structure which changed the cross-sectional area of the laminated waveguide as shown in FIG.

  The conversion unit 13 includes a first laminated waveguide line unit 210, a second laminated waveguide line unit 220, and a laminated waveguide line unit 230. Of the pair of conductor layers of the first laminated waveguide line portion 210, the second laminated waveguide line portion 220, and the laminated waveguide line portion 230, the first main surface 1a of the substrate 1 is provided. The upper conductor layers 211, 221, and 231 provided on the upper surface are formed in a planar shape, and the upper conductor layers 211, 221, and 231 are integrally formed. Of the pair of conductor layers of the first laminated waveguide line portion 210, the second laminated waveguide line portion 220, and the laminated waveguide line portion 230, the first main surface 1a of the substrate 1 is provided. The lower conductor layers 212, 222, and 232 facing the upper conductor layers 211, 221, and 231 provided in are arranged on different planes so that parts thereof overlap each other in plan view. These lower conductor layers are connected to each other by a via-hole conductor group 41 in the overlapping region.

  The width direction dimension W with respect to the signal transmission direction of the converter 13 is the same as the width direction dimension of the laminated waveguide 4 and may be set as appropriate depending on the frequency of the transmission signal. For example, when the frequency of the transmission signal is 76.5 GHz, W = 1.15 mm, and the cut-off frequency is set at about 43 GHz.

  Further, the end portions of the lower conductor layers 212, 222, and 232 in the signal transmission direction are provided by being shifted in the signal transmission direction by ¼ of the wavelength λ of the transmission signal. The length L parallel to the signal transmission direction of the converter 13 is set to 3λ / 4 so as to cover the lower conductor layers 212, 222, and 232 when viewed in plan. For example, L = 0.9 mm when the frequency of the transmission signal is 70 to 85 GHz.

  The laminated waveguide line constituting the conversion unit 13 includes the via-hole conductor groups 41 and 42 together with the pair of conductor layers as described above.

  The via-hole conductor groups 41 and 42 are arranged along the signal transmission direction at intervals of less than ½ of the cutoff frequency of the transmission signal to form an electrical side wall of the laminated waveguide, A waveguide is constituted by the conductor layer.

  With reference to Fig.5 (a)-(e), it demonstrates concretely for every dielectric material layer.

  FIGS. 5A to 5D are plan views of the dielectric layers 31, 32, 33, and 34 developed for each layer and viewed from the first main surface 1a side. FIG. 5E is a plan view of the dielectric layer 34 as viewed from the second main surface 1b side.

  As shown in FIG. 5A, the strip conductor 12 b and the upper conductor layers 211, 221, and 231 of the conversion unit 13 connected to the strip conductor 12 b are formed on the surface of the dielectric layer 31. The upper conductor layer 51 is formed with one end connected to the end of the upper conductor layer 231. In addition, two rows of via-hole conductor groups 41 and 42 for side walls are formed inside the dielectric layer 31.

  Further, the upper conductor layer 51 and the end portion of the multilayer waveguide 4 overlap each other when viewed from above, and above the pair of main conductor layers forming the upper conductor layer 51 and the multilayer waveguide 4. The boundary wall forming via-hole conductor group 43 that electrically connects the end portions of the upper conductor layer 61 is positioned in the direction perpendicular to the signal transmission direction at intervals of less than half of the cutoff wavelength of the transmission signal. Arranged inside.

  As shown in FIG. 5B, the ground conductor 12 c and the sub conductor layer 53 constituting the microstrip line 12 are integrally formed on the surface of the dielectric layer 32. In addition, in the dielectric layer 32, two rows of via-hole conductor groups 41 and 42 for sidewalls and a boundary wall forming via-hole conductor group 43 that connects the ground conductor 12c and the lower conductor layer 212 are formed.

  As shown in FIG. 5 (c), on the surface of the dielectric layer 33, the lower conductor layer 212, the sub conductor layer 54, and the upper conductor that is one of the pair of main conductor layers constituting the laminated waveguide 4. The layer 61 is electrically connected and formed integrally. In addition, a boundary wall forming via hole conductor group 43 that electrically connects two rows of via hole conductor groups 41 and 42 and the lower conductor layers 212 and 222 is formed inside the dielectric layer 33.

  As shown in FIG. 5D, the lower conductor layer 222, the sub conductor layer 54, and the sub conductor layer 53 constituting the laminated waveguide 4 are integrally formed on the surface of the dielectric layer 34. . In addition, a via-hole conductor group 43 for forming a boundary wall that electrically connects two rows of via-hole conductor groups 41 and 42 and the lower conductor layers 222 and 232 is formed inside the dielectric layer 34.

  As shown in FIG. 5 (e), on the lower surface of the dielectric layer 34, the lower conductor layer 62 located on the lower side of the lower conductor layer 232 and the main conductor layer of the laminated waveguide 4. Are integrally formed.

  Here, the sidewall via-hole conductor groups 41 and 42 are also arranged between the upper conductor layer 61 and the lower conductor layer 62 of the multilayer waveguide 4 to form the sidewall of the multilayer waveguide 4. It also functions as a side wall conductor group.

  When the laminated waveguide 4 and the laminated waveguide are composed of a plurality of dielectric layers, it is preferable to provide a sub conductor layer between the dielectric layers in parallel with the main conductor layer. The sub conductor layer is a strip-like conductor layer extending along the arrangement direction of the via hole conductor groups so as to electrically connect the via hole conductor groups existing in the same dielectric layer for each column.

  Such a sub-conductor layer can suppress transmission signal leakage and suppress poor connection between the layers of the through conductors even when stacking misalignment occurs between the plurality of dielectric layers.

  The laminated waveguide 4 and the conversion unit 13 as described above can provide a high-frequency module with little transmission loss.

  The high-frequency module of the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the scope of the invention.

  For example, the high-frequency module of the present invention is preferably arranged so that the protective member 7 contacts the conversion unit 13. Accordingly, the size of the accommodation space can be further reduced, heat exchange between the conversion unit 13 and the protection member 7 is facilitated, and the cooling effect of the high-frequency element 2 is further improved. This is because the heat of the high-frequency element 2 is transmitted to the protective member 7 made of a metal casing through the conversion unit 13 electrically connected thereto, and can be radiated into the air.

DESCRIPTION OF SYMBOLS 1 Board | substrate 1a 1st main surface 1b 2nd main surface 2 High frequency element 3 Grounding via-hole conductor group 4 Laminated waveguide 6 Connection body 7 Protective member 8 Temperature sensitive resistor 9 Transmission line 10 Input / output part 11 Bonding wire 12 Microstrip line 12b Strip conductor 12c Ground conductor 13 Conversion section

Claims (2)

A substrate,
A high-frequency element disposed on the substrate;
A ground via-hole conductor group that is formed immediately below a region in which the high-frequency element is mounted on the substrate and connects the high-frequency element to a ground potential, disposed inside the substrate, a dielectric layer, and the dielectric layer And a pair of main conductor layers sandwiching the dielectric layer and a plurality of via-hole conductors that penetrate the dielectric layer and electrically connect the pair of main conductor layers with an interval of less than half of the cutoff wavelength of the high-frequency signal transmitted A laminated waveguide comprising: disposed side wall conductor groups;
A converter for deriving the high frequency signal from the laminated waveguide onto the substrate;
A connection body for connecting the high-frequency element and the laminated waveguide through the conversion unit;
A protective member that forms a housing space that houses the high-frequency element, the connection body, and the conversion unit;
A temperature compensation circuit having a temperature-sensitive resistor, and correcting a frequency variation with respect to the temperature of the high-frequency element by a resistance value corresponding to the temperature obtained from the temperature-sensitive resistor,
The temperature-sensitive resistor is a high-frequency module disposed on the substrate and connected to the ground via-hole conductor group inside the substrate. The temperature compensation circuit is:
A resistor,
The temperature sensitive resistor connected in series to the resistor; and
The high-frequency module according to claim 1, further comprising: an output unit that outputs an intermediate voltage connected between the resistor and the temperature-sensitive resistor.

Images