JP2008259100A - Micromechanical resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micromechanical resonator capable of utilizing a resonant frequency of a higher frequency band than the conventional micromechanical resonator. <P>SOLUTION: A micromechanical resonator according to the present invention comprises a cylindrical resonator 2. The resonator 2 is supported so as to be oscillated within a plane in parallel with a substrate 7. Furthermore, first to eighth electrodes 30 to 37 are circularly disposed oppositely to the outer circumferential surface or the inner circumferential surface of the resonator 2, and a gap is formed between the first to eighth electrodes 30 to 37 and the outer circumferential surface or the inner circumferential surface of the resonator 2. A main voltage is applied to the resonator 2 and a high frequency signal is input to a plurality of predetermined electrodes in the first to eighth electrodes 30 to 37, thereby resonating the resonator 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resonator that converts an input high-frequency signal into a mechanical signal, and then converts the high-frequency signal back to a high-frequency signal and outputs the same, and more particularly, a micromechanical resonator manufactured using a microfabrication technique in the semiconductor field. It is about.

  In recent years, so-called microelectromechanical system (MEMS) technology has been developed that uses microfabrication technology in the semiconductor field to form a fine mechanical structure integrated with an electronic circuit, and is applied to frequency filters and resonators. Is being considered.

  FIG. 10 shows a conventional micro mechanical resonator using the MEMS technology (Non-patent Document 1, Patent Document 1). The micromechanical resonator (120) includes a plate-like resonator (100) on a substrate (107), and the resonator (100) has support portions (103) at three locations, both ends and a central portion. A resonant beam (102) is provided between two supporting portions (103) and (103) adjacent to each other. A support beam (101) protrudes from each support portion (103), and a base end portion of each support beam (101) is fixed to the substrate (107) by an anchor (104). As a result, the resonator (100) is held at a position slightly lifted from the surface of the substrate (107).

  On the substrate (107), an input electrode (106) and an output electrode (105) are provided between the two resonance beams (102) and (102) of the resonator (100), and one of the resonance beams is provided. A predetermined gap G is formed between (102) and the input electrode (106) and between the other resonant beam (102) and the output electrode (105). A high frequency power source (108) is connected to the input electrode (106), and a main voltage power source (109) is connected to one anchor (104).

  When a high frequency signal Vi is input to the input electrode (106) in a state where the DC voltage Vp is applied to the resonator (100) via the anchor (104), the input electrode (106) and the resonant beam (102) are interposed between them. An alternating electrostatic force is generated, and the resonator (100) vibrates in a direction perpendicular to the surface of the substrate (107) by the electrostatic force. Due to the vibration of the resonator (100), the capacitance formed between the resonator (100) and both electrodes (105) (106) changes, and the change in the capacitance is the output electrode (105). Is output as a high-frequency signal Io.

  FIG. 11 shows another conventional micromechanical resonator (Non-Patent Document 2). The micromechanical resonator (200) includes a cylindrical resonator (210), an output electrode (205), and a drive electrode (206) on a substrate (207). The cylindrical resonator (210) has an anchor (204) at the center of the cylindrical resonator (210), and two support beams (two orthogonal to each other through the anchor (204)). 201).

  A hollow portion formed in the center of the cylindrical resonator (210) is partitioned by the support beam (201), and four fan-shaped hollow portions are formed. The anchor (204) is fixed to the substrate (207), and the cylindrical resonator (210) is slightly lifted from the surface of the substrate (207) by the anchor (204) and the support beam (201). Is retained. A main voltage power source (209) is connected to the cylindrical resonator (210) via an anchor (204) and a support beam (201).

  In addition, four fan-shaped drive electrodes (206) to (206) projecting from the substrate (207) are arranged in the four fan-shaped hollow portions formed in the cylindrical resonator (210). ing. A high frequency power source (208) is connected to the four fan-shaped drive electrodes (206) to (206). Further, two output electrodes (205) and (205) are arranged to face the outer peripheral surface of the resonator (210). An output circuit (211) is connected to the two output electrodes (205) and (205).

  In a state where a DC voltage Vp is applied to the cylindrical resonator (210) via the anchor (204) and the support beam (201), a high frequency signal Vi is applied to the four fan-shaped drive electrodes (206) to (206). When input, an alternating electrostatic force is generated between the four fan-shaped drive electrodes (206) to (206) and the cylindrical resonator (210), and the cylindrical resonator (210) is generated by the electrostatic force. It vibrates in a plane parallel to the surface of the substrate (207). Due to the vibration of the cylindrical resonator (210), the capacitance between the cylindrical resonator (210) and the two output electrodes (205) and (205) changes, and the change in the capacitance is 2. The high-frequency signal Io is output from the two output electrodes (205) and (205).

M.U.Demirci and C.T.-C.Nguyen, "Higher-Mode Free-Free Beam Micromechanical Resonators," Proceedings, 2003 IEEE Int. Frequency Control Symposium, Tampa, Florida, May5-8, 2003, pp.810-818. S.−S.Li, Y.-W.Lin, Y.Xie, Z.Ren, and CT-C.Nguyen, “Micromechanical“ Hollow-Disk ”Ring Resonators,” Proceedings, 17th Int. IEEE Micro Electro Mechanical Systems Conf., Maastricht, The Netherlands, Jan. 25-29, 2004, pp.821-824. Patent No. 3790104

  In the conventional micromechanical resonator as described above, in addition to the primary resonance mode, higher order resonance modes such as the secondary resonance mode and the tertiary resonance mode are mixedly generated. It is also possible to generate resonance modes having different shapes at the maximum amplitude of resonating resonators. When the micromechanical resonator is used in a high frequency region such as a high-frequency wireless communication device operating in the GHz band, the above-described resonance mode can be used.

  However, in the conventional micromechanical resonator, when the resonance frequency in the higher order resonance mode is used in order to obtain a high frequency region, the amplitude of the resonance frequency in the higher order resonance mode is primary, secondary, etc. It was very low compared to the amplitude of the resonance frequency obtained in the low-order resonance mode. For this reason, it is very difficult to use the resonance frequency obtained in the higher-order resonance mode.

  In addition, even in the case of using a resonance mode in which the shape of the resonating resonator is different in the maximum amplitude in a conventional micromechanical resonator, it is necessary to use a higher-order resonance mode in order to obtain a resonance frequency in a high frequency band. was there. However, the resonance frequency obtained thereby is very low compared to the resonance frequency obtained in the first-order and second-order resonance modes such as the second-order resonance mode, and the resonance is different in shape at the maximum amplitude. Even in the mode, it is very difficult to use the resonance frequency in the high frequency band.

  An object of the present invention is to provide a micromechanical resonator that can use a resonance frequency in a higher frequency band than a conventional micromechanical resonator.

  The micromechanical resonator according to the present invention includes, on a substrate (7), an annular resonator (2) and an eighth resonator disposed in a circle facing the outer peripheral surface or inner peripheral surface of the resonator (2). And two electrodes (30) to (37). The resonator (2) is supported so as to be able to vibrate in a plane parallel to the substrate (7), and each of the eight electrodes (30) to (37) is the resonator (2). A gap portion is formed between the outer peripheral surface or the inner peripheral surface of each other.

  A main voltage is applied to the resonator (2), and a high-frequency signal is input to a predetermined plurality of electrodes among the eight electrodes (30) to (37). An alternating electrostatic force is generated between 2) and the plurality of electrodes, and the resonator (2) vibrates. At this time, the resonator (2) resonates in the resonance mode in which the shape at the maximum amplitude of the resonator to be resonated is different by selecting an electrode for inputting a high-frequency signal among the eight electrodes (30) to (37). To do.

  Here, each of the eight electrodes (30) to (37) arranged in a circle along the resonator (2) is sequentially arranged, the first electrode (30), the second electrode (31), and the third electrode. (32), fourth electrode (33), fifth electrode (34), sixth electrode (35), seventh electrode (36) and eighth electrode (37).

  When a high frequency signal is input to the first electrode 30, the second electrode 31, the third electrode 32, and the fourth electrode 33 among the first to eighth electrodes 30 to 37, A resonance mode in which the shape of the resonator (2) at the maximum amplitude expands in a plane parallel to the substrate (7), and a surface in which the shape of the resonator (2) at the maximum amplitude is parallel to the substrate (7) The resonator (2) resonates in a resonance mode that contracts inside. Hereinafter, this resonance mode is referred to as an A mode.

  When a high frequency signal is inputted to the first electrode (30), the second electrode (31), the fifth electrode (34) and the sixth electrode (35), the shape of the resonator (2) at the maximum amplitude is changed to the substrate. The resonator (2) resonates in an elliptical resonance mode in a plane parallel to (7). Hereinafter, this resonance mode is referred to as a B mode.

  Furthermore, when a high frequency signal is inputted to the first electrode (30), the third electrode (32), the fifth electrode (34) and the seventh electrode (36), the shape of the resonator (2) at the maximum amplitude is changed to the substrate. Eight directions facing each of the first to eighth electrodes (30) to (37) from the center point of the resonator (2) in a plane parallel to (7) are antinodes of vibration, and the resonator (2 ) In the resonance mode having a shape in which the amplitude in the direction facing the first electrode (30), the third electrode (32), the fifth electrode (34), and the seventh electrode (36) from the center of the resonator ( 2) Resonates. Hereinafter, this resonance mode is referred to as C mode.

  The A mode and the B mode are resonance modes that can be realized not only by the micromechanical resonator of the present invention but also by the conventional micromechanical resonator. The C mode is a resonance mode that is unique to the micromechanical resonator of the present invention. is there.

  The resonator (2) that resonates in the C mode has more antinodes than the resonator (2) that resonates in the A mode and the B mode. That is, a resonance frequency in a higher frequency band than the resonance frequency obtained from the resonator (2) resonating in the A mode and the B mode is obtained from the resonator (2) resonating in the C mode.

  Therefore, according to the micromechanical resonator of the present invention, it is possible to obtain a resonance frequency in a frequency band higher than that of the conventional micromechanical resonator.

  Further, in a specific configuration, the first to eighth electrodes (30) to (37) are arranged to face the outer peripheral surface of the resonator (2) and the inner periphery of the resonator (2). A bias electrode (38) is disposed to face the surface, and a bias voltage can be applied to the bias electrode (38).

  According to this specific configuration, an electrostatic force is generated between the resonator (2) and the bias electrode (38) by applying a bias voltage to the bias electrode (38), and the resonator (2) is generated by the electrostatic force. ) Receives a tensile force or a compressive force in a plane parallel to the surface of the substrate (7). As a result, the resonance frequency of the resonator (2) changes. Here, since the bias voltage can be adjusted with a continuous value, the resonant frequency of the resonator (2) can be continuously finely adjusted.

  In another specific configuration, a high-frequency signal input circuit (64) is connected to the first to eighth electrodes (30) to (37) via a switch circuit, and a predetermined plurality of signals are switched by switching the switch circuit. A high frequency signal can be input to the electrode.

  According to this specific configuration, it is possible to select an electrode for inputting a high-frequency signal among the first to eighth electrodes (30) to (37), and the shape of the resonator (2) at the maximum amplitude. It is possible to select different resonance modes.

  In another specific configuration, the switch circuit may be configured such that each of the first to eighth electrodes (30) to (37) is a high-frequency signal input circuit (64) or a high-frequency signal output circuit (63). It is composed of eight switch elements (80) to (87) to be switchably connected to one circuit.

  With this specific configuration, it is possible to select a resonance mode having a different shape at the maximum amplitude of the resonator (2), and a high-frequency signal in response to the resonance of the resonator (2) is supplied to the high-frequency signal output circuit (63). It can be obtained from the connected electrodes.

  In another specific configuration, the first to eighth electrodes (30) to (37) are alternately connected to the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63) in the order of their arrangement. ing.

  According to this specific configuration, the resonator (2) can be resonated in the C-mode resonance mode.

  According to the micromechanical resonator according to the present invention, it is possible to use a resonance frequency in a higher frequency band than the conventional micromechanical resonator.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
First, a micromechanical resonator body (1) constituting a micromechanical resonator of the present invention will be described with reference to FIGS.
A cylindrical resonator (2) is provided on the substrate (7), and a diameter line passing through the center point of the resonator (2) in a plane parallel to the substrate (7) and the resonator (2) A prismatic support beam (5) protrudes from the outer peripheral surface of the resonator (2) perpendicular to the outer peripheral surface. The tip of the support beam (5) is coupled to an anchor (4) protruding from the substrate (7).

  As shown in FIG. 2, the resonator (2) vibrates in a plane parallel to the substrate (7) at a position slightly lifted from the substrate (7) by the anchor (4) and the support beam (5). Is held possible.

  The resonator (2) has, for example, a cylindrical shape having an outer diameter of 10 μm, an inner diameter of 5 μm, and a thickness of 5 μm. For the material of the resonator (2), anchor (4) and support beam (5), a conductive material such as silicon or aluminum is used. For example, silicon or glass is used as the material of the substrate (7).

  The first electrode (30), the second electrode (31), the third electrode (32), the fourth electrode are arranged along the outer peripheral surface of the resonator (2) at positions facing the outer peripheral surface of the resonator (2). An electrode (33), a fifth electrode (34), a sixth electrode (35), a seventh electrode (36), and an eighth electrode (37) are arranged in a circle at substantially equal intervals. A predetermined gap (for example, 0.5 to 1 μm) is formed between the resonator (2) and the first to eighth electrodes (30) to (37). As the material of the first to eighth electrodes (30) to (37), for example, a conductive material such as silicon or aluminum is used.

  A cylindrical bias electrode (38) projects from the substrate (7) on the inner periphery of the resonator (2). A predetermined gap (for example, 0.5 to 1 μm) is formed between the resonator (2) and the bias electrode (38). The bias electrode (38) is made of a conductive material such as silicon or aluminum.

<First embodiment>
A first embodiment of the micromechanical resonator (11) of the present invention using the above-described micromechanical resonator body (1) will be described with reference to FIG.
The micro mechanical resonator (11) includes the micro mechanical resonator body (1), a switch circuit (9), a high frequency signal input circuit (64), a bias power source (61), a main voltage power source (62), and a high frequency signal output. It comprises a circuit (63).

  A main voltage power source (62) is connected to one anchor (4) of the micro mechanical resonator body (1), and a DC voltage Vp is applied. A high frequency signal output circuit (63) is connected to the other anchor (4). A bias power source 61 is connected to the bias electrode 38 and a DC voltage Vb is applied. The first to eighth electrodes (30) to (37) of the micromechanical resonator main body (1) are connected to the high-frequency signal input circuit (64) via the switch circuit (9).

  Specifically, the switch circuit (9) includes on / off type first switch element (90), second switch element (91), third switch element (92), fourth switch element (93), It is composed of a fifth switch element (94), a sixth switch element (95), a seventh switch element (96), and an eighth switch element (97). The first to eighth switch elements (90) to (97) can be turned on / off independently.

  The first electrode (30) is connected to the high frequency signal input circuit (64) via the first switch element (90), and the second electrode (31) is input to the high frequency signal via the second switch element (91). The circuit (64) is connected, the third electrode (32) is connected to the high-frequency signal input circuit (64) via the third switch element (92), and the fourth electrode (33) is connected to the fourth switch element (93). The fifth electrode 34 is connected to the high frequency signal input circuit 64 through the fifth switch element 94, and the sixth electrode 35 is connected to the high frequency signal input circuit 64 through the fifth switch element 94. The sixth switch element (95) is connected to the high frequency signal input circuit (64), the seventh electrode (36) is connected to the high frequency signal input circuit (64) via the seventh switch element (96), and the eighth switch The high frequency signal input circuit (64) is connected to the eighth electrode (37) through the element (97).

  The high frequency signal input circuit (64) includes a high frequency power source (60), and a high frequency voltage Vi is applied to the first to eighth electrodes (30) to (37) via the switch circuit (9). As a result, a tensile force or a compressive force is generated between the electrode to which the high frequency voltage Vi is applied and the resonator (2) due to the alternating electrostatic force in response to the phase of the high frequency signal.

  Here, since the first to eighth electrodes (30) to (37) are fixed on the substrate (7), the resonator (2) vibrates by the alternating electrostatic force. The shape at the maximum amplitude when the resonator (2) resonates is determined by the selection of the electrode to which the high frequency voltage Vi is to be applied.

  When a high frequency signal is input to the first electrode 30, the second electrode 31, the third electrode 32, and the fourth electrode 33 among the first to eighth electrodes 30 to 37, A resonance mode in which the shape of the resonator (2) at the maximum amplitude expands in a plane parallel to the substrate (7), and a surface in which the shape of the resonator (2) at the maximum amplitude is parallel to the substrate (7) The resonator (2) resonates in the A mode, which is a resonance mode having a shape that contracts inside.

  When a high frequency signal is inputted to the first electrode (30), the second electrode (31), the fifth electrode (34) and the sixth electrode (35), the shape of the resonator (2) at the maximum amplitude is changed to the substrate. The resonator (2) resonates in a B mode, which is an elliptical resonance mode in a plane parallel to (7).

  Furthermore, when a high frequency signal is inputted to the first electrode (30), the third electrode (32), the fifth electrode (34) and the seventh electrode (36), the shape of the resonator (2) at the maximum amplitude is changed to the substrate. Eight directions facing each of the first to eighth electrodes (30) to (37) from the center point of the resonator (2) in a plane parallel to (7) are antinodes of vibration, and the resonator (2 ) In the C mode, which is a resonance mode having a shape in which the amplitude in the direction facing the first electrode (30), the third electrode (32), the fifth electrode (34), and the seventh electrode (36) from the center is maximum. The resonator (2) resonates.

  The A mode and the B mode are resonance modes that can be realized not only by the micromechanical resonator of the present invention but also by the conventional micromechanical resonator. The C mode is a resonance mode that is unique to the micromechanical resonator of the present invention. is there. The resonator (2) that resonates in the C mode has more antinodes than the resonator (2) that resonates in the A mode and the B mode.

  Therefore, according to the micromechanical resonator of the present invention, a resonance frequency in a higher frequency band than the resonance frequency obtained from the resonator (2) resonating in the A mode and the B mode resonates in the C mode. It is possible to obtain a resonance frequency in a frequency band higher than that of the micromechanical resonator.

  The capacitance between the resonator (2) and the first to eighth electrodes (30) to (37) is the same as that of the resonator (2) and the first to eighth electrodes (30) due to the vibration of the resonator (2). ) To (37) depending on the distance. Therefore, the resonance frequency of the vibration of the resonator (2) that resonates changes according to the capacitance between the resonator (2) and the electrode. Therefore, the capacitance has a high frequency component corresponding to the resonance frequency of the resonator (2), and the high frequency component is converted into a high frequency current Io via an anchor (4) connected to the high frequency signal output circuit (63). Output to the outside.

  In the micromechanical resonator (11), applying a bias voltage Vb to the bias electrode (38) generates an electrostatic force between the resonator (2) and the bias electrode (38). The child (2) receives a tensile force in the direction toward the bias electrode (38). As a result, the resonance frequency of the resonator (2) can be changed. Therefore, by adjusting the bias voltage Vb applied to the bias electrode (38), it is possible to continuously fine-tune the resonance frequency of the high-frequency signal output from the anchor (4).

<Second embodiment>
A second embodiment of the micromechanical resonator (10) using the above-described micromechanical resonator body (1) will be described with reference to FIG.
The micro mechanical resonator (10) includes a micro mechanical resonator body (1), a switch circuit (8), a high frequency signal input circuit (64), a bias power source (61), a main voltage power source (62), and a high frequency signal output circuit. (63).

  A main voltage power source (62) is connected to one anchor (4) of the micro mechanical resonator body (1), and a DC voltage Vp is applied. A bias power source (61) is connected to the bias electrode (38), and a DC voltage Vb is applied. The high frequency signal input circuit (64) or the high frequency signal output circuit (63) is connected to the first to eighth electrodes (30) to (37) of the micromechanical resonator main body (1) via the switch circuit (8). It is connected to the.

  Specifically, the first electrode (30) is connected to the high frequency signal input circuit (64) and the high frequency signal output circuit (63) via the first switch element (80), and the second electrode (31) is the second electrode. The high frequency signal input circuit (64) and the high frequency signal output circuit (63) are connected via the switch element (81), and the third electrode (32) is connected to the high frequency signal input circuit (64 via the third switch element (82). ) And the high-frequency signal output circuit (63), and the fourth electrode (33) is connected to the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63) via the fourth switch element (83). The five electrodes (34) are connected to the high frequency signal input circuit (64) and the high frequency signal output circuit (63) through the fifth switch element (84), and the sixth electrode (35) connects the sixth switch element (85). To the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63), and the seventh electrode (36) is connected to the high-frequency signal input circuit (64) and the high-frequency signal via the seventh switch element (86). Is connected to a force circuit (63), the eighth electrode (37) is connected to the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63) through the eighth switch element (87).

  The first to eighth switch elements (80) to (87) can be independently switched to one of the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63). .

  The high frequency signal input circuit (64) includes a high frequency power source (60), and a high frequency voltage Vi is applied to the first to eighth electrodes (30) to (37) via the switch circuit (8). As a result, a tensile force or a compressive force is generated between the electrode to which the high frequency voltage Vi is applied and the resonator (2) due to the alternating electrostatic force in response to the phase of the high frequency signal.

  Here, since the first to eighth electrodes (30) to (37) are fixed on the substrate (7), the resonator (2) vibrates by the alternating electrostatic force. The shape at the maximum amplitude when the resonator (2) resonates is determined by the selection of the electrode to which the high frequency voltage Vi is to be applied.

  The capacitance between the resonator (2) and the first to eighth electrodes (30) to (37) is the same as that of the resonator (2) and the first to eighth electrodes due to the vibration of the resonator (2). It changes according to the distance between (30)-(37). Therefore, the resonance frequency of the vibration of the resonator (2) that resonates changes according to the capacitance between the resonator (2) and the electrode. Therefore, the capacitance has a high-frequency component corresponding to the resonance frequency of the resonator (2), and the high-frequency component serves as a high-frequency current Io via an electrode connected to the high-frequency signal output circuit (63). The resonance frequency is output to the outside.

  The micromechanical resonator (10) is also connected to the high frequency signal output circuit (63) by adjusting the bias voltage Vb applied to the bias electrode (38) as in the first embodiment. It is possible to continuously fine-tune the resonance frequency of the high-frequency signal output from the electrode.

  Next, the shape of the resonator (2) generated by the operation of the switch circuit (8) in the micro mechanical resonator (10) at the maximum amplitude in the resonance state will be described.

  As shown in FIG. 5, in the micro mechanical resonator (10), the first switch element (80), the second switch element (81), the third switch element (82) and the fourth switch element (83) are switched. The first electrode (30), the second electrode (31), the third electrode (32) and the fourth electrode (33) are connected to the high-frequency signal input circuit (64), and the fifth switch element (84), sixth The switch element (85), the seventh switch element (86) and the eighth switch element (87) are switched, and the fifth electrode (34), the sixth electrode (35), the seventh electrode (36) and the eighth electrode ( 37) and the high-frequency signal output circuit (63) are connected, the resonator (2) resonates in the A mode.

  Further, as shown in FIG. 6, in the micro mechanical resonator (10), the first switch element (80), the second switch element (81), the fifth switch element (84) and the sixth switch element (85) are provided. By switching, the first electrode (30), the second electrode (31), the fifth electrode (34) and the sixth electrode (35) are connected to the high frequency signal input circuit (64), and the third switch element (82) The fourth switch element (83), the seventh switch element (86) and the eighth switch element (87) are switched, and the third electrode (32), the fourth pole (33), the seventh electrode (36) and the When the eight electrodes (37) and the high-frequency signal output circuit (63) are connected, the resonator (2) resonates in the B mode.

  Further, as shown in FIG. 7, in the micromechanical resonator (10), the first switch element (80), the third switch element (82), the fifth switch element (84) and the seventh switch element (86) are provided. By switching, the first electrode (30), the third electrode (32), the fifth electrode (34), the seventh electrode (36) and the high-frequency signal input circuit (64) are connected, and the second switch element (81) The fourth switch element (83), the sixth switch element (85) and the eighth switch element (87) are switched, and the second electrode (31), the fourth electrode (33), the sixth electrode (35) and the When the eight electrodes (37) and the high-frequency signal output circuit (63) are connected, the resonator (2) resonates in the C mode.

  FIG. 8 is a diagram for explaining the shape of the resonator (2) that resonates in the A mode, the B mode, and the C mode at the maximum amplitude. The solid line represents the shape of the resonator (2) when not oscillating, and the two-dot chain line represents the shape of the resonating resonator at the maximum amplitude.

  FIGS. 8A and 8B are diagrams for explaining the shape of the resonator (2) that resonates in the A mode at the maximum amplitude. In the A mode, the resonance mode in which the shape of the resonator (2) expands at the maximum amplitude as shown by the two-dot chain line in FIG. 8 (A) and the maximum amplitude as shown by the two-dot chain line in FIG. 8 (B). There is a resonance mode in which the shape of the resonator (2) contracts.

  FIG. 8C is a diagram for explaining the shape of the resonator (2) resonating in the B mode at the maximum amplitude. In the B mode, the shape of the resonator (2) is elliptical with the maximum amplitude as shown by a two-dot chain line.

  Further, FIG. 8D is a diagram for explaining the shape of the resonator (2) resonating in the C mode at the maximum amplitude. In the C mode, the shape of the resonator (2) with the maximum amplitude as shown by the two-dot chain line is the first to eighth electrodes (from the center point of the resonator (2) in a plane parallel to the substrate (7). The eight directions facing each of 30) to (37) are antinodes of vibration, and the directions facing the first electrode, the third electrode, the fifth electrode, and the seventh electrode from the center of the resonator (2) are peaks.

  In the resonator (2) resonating in the C mode, the shape of the resonating resonator at the maximum amplitude has more antinodes than the resonator (2) resonating in the A mode and the B mode. That is, in the low-order resonance mode, the resonator (2) that resonates in the C mode has a resonance frequency in a higher frequency band than the resonance frequency obtained from the resonator (2) that resonates in the A mode and the B mode. It is done.

  Furthermore, the C mode is a resonance mode unique to the micromechanical resonator of the present invention. Therefore, in the micro mechanical resonator of the present invention, it is possible to use a resonance frequency belonging to a higher frequency band in the GHz band than the conventional micro mechanical resonator.

  In the above embodiment, the micromechanical resonator (10) of the present invention provided with the switch circuit (8) has been described. However, in the micromechanical resonator (11) provided with the switch circuit (9), C It is possible to obtain a mode resonance mode.

  FIG. 9 shows the A-mode contraction vibration (2) of the resonator (2) when the bias voltage Vb applied to the bias electrode (38) is changed by computer simulation in the micromechanical resonator body (1) of the present invention. It is a graph which shows the result of having calculated the change of the resonant frequency in the 2nd mode). In the calculation, the resonator (2) has an outer diameter of 10 μm, an inner diameter of 5 μm, and a thickness of 2 μm, and the resonance frequency of the resonator (2) without applying the bias voltage Vb to the bias electrode (38) was set to 600 MHz.

  As shown in FIG. 9, when the bias voltage Vb continuously changes from 0 V to 100 V, the resonance frequency changes from 600 MHz to 616 MHz with a smooth curve. Therefore, according to the micromechanical resonator of the present invention, by adjusting the bias voltage Vb applied to the bias electrode (38), it is possible to continuously fine-tune the resonance frequency of the output high-frequency signal. ing.

  According to the micromechanical resonator of the present invention, by resonating the resonator (2) in the C mode that is a resonance mode inherent to the micromechanical resonator, a higher frequency band than that of the conventional micromechanical resonator is obtained. The resonance frequency can be used.

  Therefore, the micromechanical resonator of the present invention is effective for a device that requires a higher frequency, for example, an RF wireless device such as a remote keyless entry system, spread spectrum communication, or software defined radio.

  In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, a higher resonance frequency can be realized by using a material having a high Young's modulus, such as diamond, as the material of the resonator (2).

  In the above embodiment, all of the first to eighth electrodes (30) to (37) are arranged along the outer peripheral surface of the resonator (2), and the bias electrode (38) is arranged along the inner peripheral side. However, the first to eighth electrodes (30) to (37) are arranged along the inner peripheral surface of the resonator (2), and the bias electrode (38) is opposed to the outer peripheral surface of the resonator (2). It is also possible to arrange them as follows.

It is a perspective view of the micro mechanical resonator main body of this invention. It is sectional drawing which follows the AA line of FIG. It is a top view of the micro mechanical resonator of 1st Example. It is a top view of the micro mechanical resonator of 2nd Example. In the micro mechanical resonator of 2nd Example, it is a figure explaining operation of the switch circuit at the time of vibrating a cylindrical resonator in A mode. In the micro mechanical resonator of 2nd Example, it is a figure explaining operation of the switch circuit at the time of vibrating a cylindrical resonator in B mode. In the micro mechanical resonator of 2nd Example, it is a figure explaining operation of the switch circuit at the time of vibrating a cylindrical resonator in C mode. It is a figure explaining the shape in the maximum amplitude of the cylindrical resonator to resonate in the micromechanical resonator of 2nd Example. It is a graph showing the change of the resonant frequency according to the bias characteristic in the micro mechanical resonator main body which concerns on this invention. It is a perspective view of the conventional micro mechanical resonator. It is a perspective view of the other conventional micro mechanical resonator.

Explanation of symbols

(1) Micromechanical resonator body
(10) (11) Micromechanical resonator
(2) Resonator
(30)-(37) 1st electrode-8th electrode
(38) Bias electrode
(4) Anchor
(5) Support beam
(60) High frequency power supply
(61) Bias power supply
(62) Main voltage power supply
(63) High frequency signal output circuit
(64) High frequency signal input circuit
(7) Board
(8) (9) Switch circuit

Claims (5)

  On the substrate (7), an annular resonator (2) and eight electrodes (30) to (37) arranged in a circle facing the outer peripheral surface or inner peripheral surface of the resonator (2). The resonator (2) is supported so as to be able to vibrate in a plane parallel to the substrate (7), and each of the eight electrodes (30) to (37) includes the resonator ( 2) A gap is formed between the outer peripheral surface and the inner peripheral surface, a main voltage is applied to the resonator (2), and a predetermined number of the eight electrodes (30) to (37) are provided. By inputting a high-frequency signal to the electrodes, an alternating electrostatic force is generated between the resonator (2) and the plurality of electrodes to vibrate the resonator (2), and the resonator (2) A micromechanical resonator that outputs a change in capacitance between the eight electrodes (30) to (37) as a high-frequency signal.   The eight electrodes (30) to (37) are disposed so as to face the outer peripheral surface of the resonator (2), and face the inner peripheral surface of the resonator (2) so as to face the bias electrode (38). The micro mechanical resonator according to claim 1, wherein a bias voltage can be applied to the bias electrode (38).   A high-frequency signal input circuit (64) is connected to the eight electrodes (30) to (37) via a switch circuit, and a high-frequency signal can be input to a plurality of predetermined electrodes by switching the switch circuit. The micromechanical resonator according to claim 1 or 2, wherein   The switch circuit is configured to connect each of the eight electrodes (30) to (37) to one of a high-frequency signal input circuit (64) and a high-frequency signal output circuit (63) in a switchable manner. The micromechanical resonator according to claim 3, comprising switch elements (80) to (87).   The eight electrodes (30) to (37) are alternately connected to the high-frequency signal input circuit (64) and the high-frequency signal output circuit (63) in the order of their arrangement. The micromechanical resonator as described.

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