Communication device

Abstract

Further improve impedance matching in communication devices. [Solution] The communication device comprises a chip 3 and a substrate member 4 on which the chip 3 and waveguide are mounted. The chip 3 has a waveguide conversion circuit section 3A and a conductive section. The waveguide conversion circuit section 3A generates a transmission signal corresponding to radio waves transmitted from the waveguide 2 or receives a reception signal corresponding to radio waves received from the waveguide. The conductive section has a signal pad, a ground pad, and a ground pad expansion section. The substrate member 4 has a signal pad mounting section 4D, a wiring section 4B, an antenna section 4C, and a space section 4E.

Description

[Technical Field]

[0001] The present invention relates to a communication device. [Background Art]

[0002] As devices for transmitting and receiving radio waves, there are coaxial connectors and cables. However, since these devices have large radio wave transmission loss, they are mainly used at relatively low frequencies. For this reason, as disclosed in Patent Document 1, various communication devices including a waveguide have been proposed for use in high frequency bands of about several tens of GHz. Some communication devices including a waveguide have a back short structure located on an extension of the waveguide. An antenna unit of an electric circuit is disposed in the back short structure, so that radio waves are transmitted. The antenna unit is connected to a chip (IC) mounted on a substrate of the communication device via a conductive portion (wiring) of the substrate. In the communication device, when radio waves are transmitted or received by the antenna unit, a signal corresponding to the radio waves flows from the chip to the conductive portion of the substrate (during radio wave transmission) or from the conductive portion of the substrate to the chip (during radio wave reception). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2006-261767 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] For example, there is a concern that the electrical characteristics of a signal (e.g., transmission characteristics and reflection characteristics) cannot be further improved in a high frequency band such as gigahertz only by taking measures or contrivances for impedance matching with respect to the back short structure or the waveguide conversion circuit itself in the chip.

[0005] An object of the present invention is to further improve impedance matching in a communication device. [Means for solving the problem]

[0006] According to the present invention, a communication device is provided comprising a chip and a substrate member, wherein the chip has a waveguide conversion circuit section and a conductive section, the waveguide conversion circuit section is configured to generate a transmission signal corresponding to radio waves transmitted from a waveguide, or to receive a reception signal corresponding to radio waves received from the waveguide, the conductive section has a signal pad, a ground pad, and a ground pad expansion section, the signal pad is a pad through which the transmission signal or the reception signal flows, the ground pad is provided on the edge of the ground pad expansion section and is conductive to the ground pad expansion section, the substrate member has a signal pad mounting section, a wiring section, an antenna section, and a space section, the signal pad mounting section is conductive to the signal pad of the conductive section via a signal bump section, the wiring section connects the signal pad mounting section and the antenna section, the antenna section has the function of transmitting or receiving the radio waves, and the antenna section is arranged in the space section.

[0007] According to the present invention, since the conductive portion of the chip has an enlarged ground pad portion that conducts to ground, impedance matching at the connection portion between the chip and the substrate on which the chip is mounted can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows a functional block diagram of a waveguide converter 1 having a communication device 5 according to an embodiment. [Figure 2] Figure 2 is a schematic diagram illustrating the configuration of the waveguide converter 1 shown in Figure 1, including the waveguide 2, chip 3, and communication device 5. [Figure 3] Figure 3 is a schematic perspective view showing the bottom surface (mounting side) of the chip 3 shown in Figure 2. [Figure 4]Figure 4A is a graph showing the transmission characteristics from the chip transmission line to the waveguide input / output section, Figure 4B is a graph showing the reflection characteristics in the chip transmission line, and Figure 4C is a graph showing the reflection characteristics in the waveguide input / output section. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature can stand alone as an independent invention.

[0010] 1. Description of the Configuration of the Embodiment As shown in Figure 1, the waveguide converter 1 comprises a waveguide 2 having a horn antenna 2A (see Figure 2), and a communication device 5 having a chip 3 and a substrate member 4 (see Figure 2).

[0011] Waveguide converter 1 is a high-frequency module and is configured to transmit and receive various types of radio waves. The waveguide converter 1 according to this embodiment is a high-frequency module suitable for radar, sensors, and wireless communication systems that use high frequencies such as gigahertz waves and terahertz waves. Furthermore, the waveguide converter 1 may function as either a transmitter or a receiver, or it may have the functions of both a transmitter and a receiver.

[0012] The applicable radio wave frequencies (GHz) for the waveguide converter 1 equipped with the communication device 5 according to this embodiment include, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, and 1500, and may also include a range between any two of the values ​​exemplified here. Furthermore, the frequency range of radio waves to which the waveguide converter 1 can be applied may be divided into multiple frequency ranges. For example, if defined by the values ​​listed above, this could be frequencies between 100 GHz and 400 GHz, and frequencies between 800 GHz and 1000 GHz.

[0013] 1-1. Waveguide 2 Waveguide 2 is a transmission path (waveguide) for high-frequency radio waves, and is a hollow member that confines and transmits electromagnetic waves. Waveguide 2 has a horn antenna 2A, but is not limited to this, and may adopt a rectangular configuration (the cross-sectional shape in the longitudinal direction is rectangular) or a circular configuration. Waveguide 2 is made of metal, and can be made of a metal material such as copper. In this embodiment, the transmission path (waveguide) of waveguide 2 extends in a straight line, but is not limited to this, and may be curved.

[0014] Waveguide 2 has a horn antenna 2A, a first flange portion 2B, and a second flange portion 2C.

[0015] The horn antenna 2A is the part that receives radio waves from outside the waveguide converter 1 during reception, and the part that radiates radio waves from the waveguide converter 1 to the outside during transmission. The horn antenna 2A is an antenna with a gradually widening aperture, and is used, for example, to efficiently radiate radio waves into space during transmission. The shape of the horn antenna 2A is not particularly limited, but a conical, pyramidal, sector-type, or other type of horn antenna can be used.

[0016] The first flange portion 2B is connected to the base end of the horn antenna 2A and is provided to accommodate the space portion 4E, which will be described later as a back short structure, and the antenna portion 4C. The first flange portion 2B has a cavity that communicates with the horn antenna 2A, and together with the horn antenna 2A, a space (waveguide) through which radio waves propagate is formed.

[0017] The first flange portion 2B, together with the second flange portion 2C, sandwiches the substrate member 4 of the communication device 5 described later. It is preferable that the first flange portion 2B and the second flange portion 2C are configured to be connectable to each other via, for example, a connecting member not shown in the drawings, so that the state of sandwiching the substrate member 4 can be maintained. The second flange portion 2C is disposed so as to close the open portion (the portion on the lower side of the drawing sheet in Fig. 2) of the space portion 4E formed in the substrate member 4, and is capable of reflecting radio waves.

[0018] 1-2. Communication Device 5 The communication device 5 is configured to perform electromagnetic interaction between external radio waves and the chip 3. As shown in Fig. 2, the communication device 5 includes the chip 3 and the substrate member 4 having a back short structure.

[0019] 1-2-1. Chip 3 The chip 3 can be constituted by a semiconductor IC chip mounted on the substrate member 4 of the communication device 5. In the embodiment, the chip 3 includes, for example, a CMOS circuit (Complementary Metal Oxide Semiconductor circuit). Note that the chip 3 is not limited to CMOS circuits, and is also applicable to SiGeBiCMOS circuits (Bipolar-CMOS circuits), other compound semiconductor circuits, and the like.

[0020] As shown in Fig. 2 and Fig. 3, the chip 3 includes a chip main body 3t and a conduction portion 3T. The conduction portion 3T is a plate-shaped portion disposed below the chip main body 3t. The chip main body 3t has a waveguide conversion circuit portion 3A, and the conduction portion 3T is electrically connected to the waveguide conversion circuit portion 3A of the chip main body 3t.

[0021] 1-2-1-1. Chip Main Body 3t (Waveguide Conversion Circuit Portion 3A) The waveguide conversion circuit section 3A of the chip body 3t is configured to generate a transmission signal corresponding to a radio wave transmitted from the waveguide 2, or receive a reception signal corresponding to a radio wave received from the waveguide. That is, the waveguide conversion circuit section 3A is composed of, for example, wiring, elements, and the like, and is configured as a circuit responsible for transmission signal processing or reception signal processing.

[0022] 1-2-1-2. Conduction portion 3T The conduction portion 3T shown in Fig. 3 includes a wiring portion 3B1, a plurality of (two in an example of the embodiment) wiring portions 3B2, a signal pad 3C1, a plurality of (two in an example of the embodiment) ground pads 3C2, and a ground pad enlarged portion 3C3. The conduction portion 3T does not include a signal processing circuit, and is, for example, a portion having a conductor for achieving impedance matching. Further, the conduction portion 3T includes a plurality of bump portions (bumps). The bump portions are formed of fine metal protrusions for electrically connecting (mounting) the chip 3 to the substrate member 4. The bumps of the conduction portion 3T include a signal bump portion 3D1, a ground bump portion 3D2, and a ground bump portion 3D3.

[0023] The constituent material of the conduction portion 3T is not limited, and for example, the conduction portion 3T can be formed of a metal material such as copper, nickel, aluminum, tin, gold, silver, or a mixed material thereof. It should be noted that all constituent elements of the conduction portion 3T may be formed of the same material, or the material may be different depending on the location.

[0024] <Wiring portion 3B1 and wiring portion 3B2> The wiring portion 3B1 and the wiring portion 3B2 electrically connect the waveguide conversion circuit portion 3A and the conduction portion 3T. The wiring portion 3B1 is connected to the signal pad 3C1, and the plurality of wiring portions 3B2 are each connected to the respective ground pad 3C2.

[0025] The wiring section 3B1 is the wiring section through which the transmit signal or receive signal flows. Here, the transmit signal is the signal generated in the waveguide conversion circuit section 3A of the chip body 3t and sent to the wiring section 4B of the substrate material 4. The receive signal is the signal received by the waveguide 2 and sent from the wiring section 4B to the waveguide conversion circuit section 3A of the chip body 3t. Furthermore, wiring section 3B2 is the wiring section that corresponds to the potential of ground.

[0026] <Signal pad 3C1, ground pad 3C2, and ground pad enlargement section 3C3> The signal pad 3C1 is a pad through which the transmit signal or receive signal flows. While the rectangular shape of the signal pad 3C1 is shown as an example, it is not limited to this; it may also be polygonal (e.g., pentagonal, hexagonal, etc.) or circular. The same applies to the ground pad 3C2, which will be described later; it may also be polygonal or circular. The signal pad 3C1 is provided with a signal bump section 3D1.

[0027] The ground pad 3C2 is a pad corresponding to the potential of ground. The ground pad 3C2 is provided with a ground bump portion 3D2. The ground pad 3C2 is located at the edge of the ground pad extension portion 3C3. The ground pad 3C2 is electrically connected to the ground pad extension portion 3C3. In other words, the ground pad 3C2 is connected at the edge of the ground pad extension portion 3C3 and is electrically conductive. The plan view shape of the ground pad 3C2 is shown as an example of a rectangular shape, but it is not limited to this and may be polygonal (e.g., pentagon, hexagon, etc.) or circular. Note that the ground pad 3C2 is provided independently of the signal pad 3C1 and the wiring portion 3B1 to prevent short circuits with them.

[0028] In one embodiment, the ground pad enlargement portion 3C3 is a ground pad having a larger area than both the signal pad 3C1 and the ground pad 3C2. The ground pad enlargement portion 3C3 is provided with a ground bump portion 3D3. The ground pad enlargement portion 3C3 is positioned between the waveguide conversion circuit portion 3A and the space portion 4E (waveguide 2), in the direction from the waveguide conversion circuit portion 3A to the space portion 4E (waveguide 2), which will be described later. The ground pad enlargement portion 3C3 is formed on the chip 3, which improves impedance matching at the connection portion between the chip 3 and the substrate member 4 on which the chip 3 is mounted.

[0029] Here, the ground pad expansion section 3C3 has a signal wavelength (the wavelength of the signal in the chip 3 and substrate material 4) as λ. This signal wavelength (received signal, transmitted signal) corresponds to the wavelength of the signal flowing through the wiring section 3B1 and the signal bump section 3D1. Furthermore, the width of the ground pad expansion section 3C3 in the direction from the signal pad mounting section of the mounting section 4D (described later) toward the antenna section 4C is denoted as d (see Figure 3). Here, the width d of the ground pad expansion section 3C3 can be defined using λ / 4. This enables stepwise impedance transformation, reducing transmission and reflection losses. Note that the effect can be obtained even if the width d of the ground pad expansion section does not perfectly match λ / 4. Specifically, for example, the width d of the enlarged ground pad is 0.50×λ / 4, 0.55×λ / 4, 0.60×λ / 4, 0.65×λ / 4, 0.70×λ / 4, 0.75×λ / 4, 0.80×λ / 4, 0.85×λ / 4, 0.90×λ / 4, 0.95×λ / 4, 1.00×λ / 4, 1.05×λ / 4, 1.10×λ / 4, 1.15×λ / 4, 1.20×λ / 4, 1.25×λ / 4, 1.30×λ / 4, 1.35×λ / 4, 1.40×λ / 4, 1.45×λ / 4, 1.50×λ / 4, and may be within the range of any two of the values ​​exemplified here. For example, the width d of the enlarged ground pad is in the range of 0.5 × λ / 4 to 1.5 × λ / 4 (a range of 0.9 × λ / 4 or more and 1.1 × λ / 4 or less).

[0030] <Signal bump section 3D1, ground bump sections 3D2, 3D3> The signal bump section 3D1 is provided on the signal pad 3C1. The signal bump section 3D1 is provided to provide electrical conductivity between the signal pad 3C1 and the signal pad mounting section of the mounting section 4D, which will be described later. The ground bump portion 3D2 is provided on the ground pad 3C2. The ground bump portion 3D2 is provided to connect the ground pad 3C2 with the ground pad mounting portion of the mounting portion 4D, which will be described later. In this embodiment, a signal bump portion 3D1 is positioned between a pair of ground bump portions 3D2, ensuring structural symmetry and making it easier to balance the chip 3 when mounting it. The ground bump portion 3D2 is provided to connect the ground pad 3C2 with the ground pad mounting portion of the mounting portion 4D, which will be described later. The ground bump section 3D3 is provided in the ground pad enlargement section 3C3. The ground bump section 3D3 is provided to be electrically connected to the ground pad enlargement section 3C3 and the ground pad mounting section of the mounting section 4D, which will be described later.

[0031] 1-2-2. Substrate component 4 As shown in Figure 2, the substrate member 4 has a substrate body 4A, a wiring section 4B, an antenna section 4C, a mounting section 4D, and a space section 4E.

[0032] The substrate body 4A can be made of a printed circuit board (PCB) having a predetermined thickness, and as shown in Figure 2, it has a front surface 4Af and a back surface 4Ab. The front surface 4Af is formed on the opposite side from the back surface 4Ab. The front surface 4Af is the top surface and is positioned opposite the conductive portion 3T described above. The substrate body 4A has, for example, a multilayer structure, and circuits and elements (not shown) in each layer are electrically connected through via holes.

[0033] The wiring section 4B electrically connects the antenna section 4C and the chip 3 (mounting section 4D). In other words, the wiring section 4B extends from the mounting section 4D located at the position of the chip 3, passes through the first flange section 2B, and connects to the antenna section 4C located in the space section 4E.

[0034] The antenna section 4C has the function of transmitting or receiving radio waves. The antenna section 4C is positioned to face the space section 4E. In other words, the antenna section 4C is positioned to protrude into the space section 4E. The antenna section 4C is fixed to the main board body 4A, for example.

[0035] The mounting section 4D, although not shown in Figure 2, has a signal pad mounting section and a ground mounting section. The mounting section 4D is formed on the front surface 4Af of the main board body 4A. The signal pad mounting section and the ground mounting section can be made up of, for example, independent metal pads. A signal bump section 3D1 is placed in the signal pad mounting section of the mounting section 4D. In other words, the signal pad mounting section of the mounting section 4D is electrically connected to the signal pad 3C1 of the conductive section 3T via the signal bump section 3D1. A ground bump section 3D2 and a ground bump section 3D2 are placed in the ground mounting section of the mounting section 4D. In other words, the ground mounting section of the mounting section 4D is electrically connected to the ground pad 3C2 and the ground pad enlargement section 3C3 via the ground bump sections 3D2 and 3D3.

[0036] The space 4E is the area on the front surface 4Af of the substrate member 4 where the waveguide 2 is positioned. Furthermore, a space 4E1 is formed within the space 4E, extending from the front surface 4Af to the back surface 4Ab of the substrate member 4. Space 4E1 corresponds to the back short hole in a so-called back short structure. The antenna portion 4C is positioned to protrude from space 4E1. While the embodiment describes space 4E1 as a hole, it is not limited to this and may be a notch formed in the substrate body 4A.

[0037] 2. Description of the operation and effects of the embodiment In the waveguide converter 1 according to this embodiment, the conductive portion 3T of the chip 3 has a ground pad enlargement portion 3C3 that is conductive to ground, thereby improving impedance matching at the connection portion between the chip 3 and the substrate member 4 on which the chip 3 is mounted. Furthermore, the configuration of the embodiment takes into account the characteristics in the 300GHz band and terahertz band (1000GHz and above), which are expected to be used in devices for future Beyond 5G and 6G communications, and makes it easier to ensure impedance matching across a wide range of frequency bands and other radio wave environmental conditions. For this reason, the configuration of the embodiment has improved applicability to the frequencies of radio waves used in communications.

[0038] Figures 4A to 4C show the results of evaluating the transmission and reflection characteristics of the waveguide converter 1 according to the embodiment. As shown in Figure 4A, by adopting the configuration of this embodiment, it can be seen that the transmission characteristics from the chip line (wiring section 3B1) to the waveguide input / output section (horn antenna 2A of the waveguide 2) are ensured at frequencies of 250 GHz and its vicinity, and at frequencies of 300 GHz and above. Furthermore, as shown in Figure 4B, the reflection characteristics in the chip line (wiring section 3B1) are -7.5dB at least from 220GHz to 340GHz, indicating that high performance is achieved over a wide range from 220GHz to approximately 340GHz. Furthermore, as shown in Figure 4C, the reflection characteristics in the waveguide input / output section (horn antenna 2A of waveguide 2) are maintained at -7.5 dB at least from 220 GHz to 320 GHz, indicating that high performance is obtained over a wide range from 220 GHz to 320 GHz.

[0039] Various embodiments are illustrated below. The embodiments shown below can be combined with each other. [Note 1] It comprises a chip and a substrate material, The chip has a waveguide conversion circuit section and a conductive section. The waveguide conversion circuit is configured to generate a transmission signal corresponding to radio waves transmitted from the waveguide, or to receive a reception signal corresponding to radio waves received from the waveguide. The conductive portion includes a signal pad, a ground pad, and a ground pad enlargement portion. The signal pad is a pad through which the transmission signal or the reception signal flows. The ground pad is provided on the edge of the enlarged ground pad portion and is electrically connected to the enlarged ground pad portion. The aforementioned substrate member has a signal pad mounting section, a wiring section, an antenna section, and a space section. The signal pad mounting section is electrically connected to the signal pad of the conductive section via the signal bump section. The aforementioned wiring section provides electrical conductivity between the signal pad mounting section and the antenna section. The aforementioned antenna unit has the function of transmitting or receiving the aforementioned radio waves. A communication device in which the antenna is located in the aforementioned space. [Note 2] The communication device described in Appendix 1, When the wavelength of the transmitted signal or the received signal is λ, the width of the ground pad enlargement portion in the direction from the signal pad mounting portion toward the antenna portion is d. A communication device in which the width d of the enlarged ground pad is in the range of 0.5 × λ / 4 to 1.5 × λ / 4. [Note 3] A communication device as described in Appendix 1 or Appendix 2, The aforementioned substrate member further has a ground mounting portion, A communication device in which the ground mounting section is electrically connected to the ground pad and the ground pad enlargement section via a ground bump section. [Explanation of symbols]

[0040] 1: Waveguide converter 2: Waveguide 2A: Horn antenna 2B: First flange section 2C: Second flange section 3: Tip 3A: Waveguide conversion circuit section 3B1: Wiring section 3B2: Wiring section 3C1: Signal Pad 3C2: Ground pad 3C3: Enlarged Ground Pad Section 3D1: Signal bump area 3D2: Ground Bump Section 3D3: Ground Bump Section 3T: Continuity part 4: Substrate material 4A: Main board 4B: Wiring section 4C: Antenna section 4D: Implementation Department 4E:Space 4E1 :Space 4Af: Front side 4Ab: Reverse side 5: Communication device

Claims

1. It comprises a chip and a substrate material, The chip has a waveguide conversion circuit section and a conductive section. The waveguide conversion circuit is configured to generate a transmission signal corresponding to radio waves transmitted from the waveguide, or to receive a reception signal corresponding to radio waves received from the waveguide. The conductive portion includes a signal pad, a ground pad, and a ground pad enlargement portion. The signal pad is a pad through which the transmission signal or the reception signal flows. The ground pad is provided on the edge of the enlarged ground pad portion and is electrically connected to the enlarged ground pad portion. The aforementioned substrate member has a signal pad mounting section, a wiring section, an antenna section, and a space section. The signal pad mounting section is electrically connected to the signal pad of the conductive section via the signal bump section. The aforementioned wiring section provides electrical conductivity between the signal pad mounting section and the antenna section. The aforementioned antenna unit has the function of transmitting or receiving the aforementioned radio waves. A communication device in which the antenna is located in the aforementioned space.

2. A communication device according to claim 1, When the wavelength of the transmitted signal or the received signal is λ, the width of the ground pad enlargement portion in the direction from the signal pad mounting portion toward the antenna portion is d. A communication device in which the width d of the enlarged ground pad is in the range of 0.5 × λ / 4 to 1.5 × λ / 4.

3. A communication device according to claim 1 or claim 2, The aforementioned substrate member further has a ground mounting portion, A communication device in which the ground mounting section is electrically connected to the ground pad and the ground pad enlargement section via a ground bump section.

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