CN103338022B - The MEMS resonator of frequency-adjustable - Google Patents

Abstract

A kind of MEMS resonator of frequency-adjustable, comprise: a resonant element, be disc, annular or symmetric polygonal structure, its center is vibration displacement node, this resonant element is positioned at the support anchor points support of displacement node by one, and the surface of this resonant element is provided with multiple micro-structural; Multiple electrode, it is positioned at periphery or the top of resonant element, has a gap between each electrode, and each electrode directly contacts with between resonant element or has a gap.The present invention, when not increasing structural complexity, realizes multiple different frequency and exports.

Description

Frequency Tunable MEMS Resonator

technical field

The present invention relates to the field of radio frequency micro-electromechanical (RFMEMS) technology, and more particularly, the present invention relates to a radio frequency micro-mechanical resonator device, especially a MEMS resonator with adjustable frequency.

Background technique

With the development of wireless communication systems towards low power consumption, small size, and multi-functions and the improvement of system integration requirements, it is urgent to develop new structures to replace traditional wireless transceiver systems. As a filtering and frequency reference device in a wireless transceiver structure, a radio frequency resonant device has a wide range of application requirements. The most widely used RF resonant devices include quartz, ceramic, surface acoustic wave (SAW) and bulk acoustic wave (FBAR) devices, which can achieve the high Q value (500-10000) required by RF and IF filters, but they are all Off-chip discrete components are not conducive to system integration and miniaturization. MEMS devices are considered to be one of the best choices to replace traditional off-chip discrete components due to their small size, low cost, low power consumption, high Q value, high linearity, and integration with IC processes. Wide application in miniaturized, low-power, portable devices provides the basis [1].

In order to meet the multi-band, multi-functional and multi-mode application requirements of future wireless communication systems, frequency-selective devices are required to have good frequency characteristics and reduce the complexity of the structure. For multi-band application requirements, it is usually necessary to build a resonator array [2] or filter array [3] to realize a single-chip system, which not only increases the complexity of the system, but also increases the cost. Therefore, it is necessary to develop a new The structure meets the application requirements of multi-band.

In view of this, the present invention proposes a novel frequency-tunable MEMS resonator, and the output of different resonant frequencies can be realized by using this structure. Different frequency outputs of the resonator are realized by changing the number, shape and size of the microstructure and the relative position to the driving electrodes. In addition, by increasing the number of electrodes, high-order vibration modes are excited to obtain high-frequency output, and by changing the connection mode between electrodes, different-order resonance modes are excited to obtain different-order resonance frequency outputs. The resonator provided by the invention can reduce the complexity of the wireless communication system, greatly improve the integration of the system, and further reduce the system cost.

Citation:

【1】C.T.-C.Nguyen, VibratingRFMEMSoverview: applicationstowirelesscommunications, inProc.SPIE: Micromachin.Microfabric.ProcessTechnol., SanJose, CA, vol.5715, Jan.22-27, 2005, pp.11-25.

【2】H.ChandrahalimandS.A.Bhave, Digitally-tunableMEMS filter using mechanically-coupled resonator array, inProc.IEEE21stInt.Conf.MicroElectroMech.Syst.(MEMS'08), Jan.13-17, 2008, pp.1020-1023.

【3】C.T.-C.Nguyen, MEMStechnologies and devices for single-chip RF front-ends (invited), Tech.Dig., CICMT'06, Denver, Colorado, April25-26, 2006.

Contents of the invention

In view of this, the main purpose of the present invention is to propose a novel frequency-tunable MEMS resonator, which can realize multiple different frequency outputs without increasing the complexity of the structure.

In order to achieve the above object, the present invention proposes a MEMS resonator with adjustable frequency, comprising:

A resonant unit is a disc-shaped, circular or symmetrical polygonal structure, the center of which is a vibration displacement node, the resonant unit is supported by a support anchor point located at the displacement node, and the surface of the resonant unit is provided with a plurality of microstructures ;

A plurality of electrodes are located on the periphery or above the resonant unit, there is a gap between each electrode, and there is a direct contact or a gap between each electrode and the resonant unit.

As can be seen from the foregoing technical scheme, the beneficial effects of the present invention are:

1. The present invention realizes the flexible adjustment of the resonant frequency by controlling the number, position, and shape of the microstructure, and realizes high-frequency output without reducing the size of the device.

2. Through simple microstructure design and electrode interconnection, the present invention realizes a variety of resonators with different frequency outputs without increasing structural complexity. These simple structural units will replace resonators in wireless communication systems Or a filter array, which can greatly improve the integration of the wireless communication system and reduce the complexity and production cost of the system.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings, wherein:

Fig. 1, Fig. 2, Fig. 3 are the structural representations of the frequency-tunable MEMS resonator proposed by the present invention;

Fig. 4 is the schematic diagram of the structure of the disk-shaped MEMS resonator when the electrodes corresponding to the microstructure-free region are excited;

Fig. 5 is the schematic diagram of the resonant mode of Fig. 4;

Fig. 6 is a structural schematic diagram of a disk-shaped MEMS resonator when excitation is applied to electrodes corresponding to the microstructure region;

FIG. 7 is a schematic diagram of a resonance mode in FIG. 6 .

detailed description

The present invention provides a MEMS resonator with adjustable frequency, as shown in Fig. 1, Fig. 2 and Fig. 3, specifically comprising:

A resonant unit 1 is a disc-shaped, circular or symmetrical polygonal structure, wherein the circular resonant unit 1 can obtain a higher resonance frequency without reducing the size of the structure, and its center is the vibration displacement node 11 , the resonant unit 1 is supported by a supporting anchor point 12 located at the displacement node 11, the material of the resonant unit 1 is silicon-based material, piezoelectric material or sapphire, and the surface of the resonant unit 1 is provided with a plurality of microstructures 13 , uniformly distributed along the equal-radius circumference of the resonant unit 1, the microstructure 13 on the resonant unit 1 is a small hole or a tooth-like structure, by changing the relative position of the microstructure 13 and the driving electrode, different resonance modes are excited, thereby To obtain different frequency outputs, change the number, shape, size and position of the microstructure in the resonant unit to obtain different frequency adjustment ranges.

A plurality of electrodes 2, which are located on the periphery or above the resonant unit 1, there is a gap between each electrode, and there is a direct contact between each electrode and the resonant unit 1 or there is a gap, the material of the electrodes 2 is metal or doped semiconductor material, said The gap between the electrode 2 and the resonance unit 1 is filled with air or solid medium or both air and solid medium. Electrostatic drive, piezoelectric drive or electrostatic-piezoelectric hybrid drive can be used between the electrodes and the resonant unit.

The invention realizes the flexible adjustment of the resonant frequency by controlling the number, position, and shape of the microstructure, and realizes high-frequency output without reducing the size of the device.

The structural features of the disk-shaped MEMS resonator are described in detail below, as shown in Figure 4 and Figure 5, Figure 6 and Figure 7, respectively, when the disk-shaped MEMS resonator applies excitation to the electrode corresponding to the microstructure-free area. The schematic diagram of the structure and the schematic diagram of the structure when excitation is applied to the electrodes corresponding to the microstructure area, including:

Disc-shaped resonant unit 1 with a radius of 18um and a thickness of 3um. The material of the resonant unit 1 is polysilicon. There are 6 fan-shaped small hole microstructures 13 on the surface. The inner and outer radii of the small holes are 4um and 8um respectively. The equal-radius circle with a radius of 10um is evenly distributed. A plurality of electrodes 2 are located on the periphery of the resonance unit 1, corresponding to the microstructure area 6 and the microstructure-free area 7 on the resonance unit in turn. There is a gap between each electrode. Multiple electrodes The drive electrode 8 and the detection electrode 9 constituting the resonant unit, electrostatic transmission is used between the electrodes and the resonant unit, and different frequency outputs can be obtained by changing the relative position of the microstructure 13 and the drive electrode 8 .

When an excitation signal is applied to the driving electrode 8, the resonance unit 1 works in the third-order whispering gallery vibration mode ( ^3rd WGM). When an excitation is applied to the electrode corresponding to the microstructure-free region 7, as shown in FIG. 13 is in the node displacement region, and the electrode 9 detects an output frequency of 140MHz. When excitation is applied to the electrode corresponding to the microstructure region 6, as shown in Figure 6, the microstructure 13 is in the large displacement region, and the output frequency of the electrode 9 is 145MHz, as shown in Fig. 4 and the frequency difference output by the structures shown in FIG. 6 are related to the number, shape and size of the microstructures 13 and their positions in the resonant unit 1.

Increasing the number of electrodes 2 and microstructures 13 can excite higher-order vibration modes (whispering gallery modes above order 3), thereby obtaining higher resonance frequencies (>200MHz). In addition, by changing the The connection mode can excite different orders of resonance modes and obtain different orders of resonance frequency outputs.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (4)

1. a MEMS resonator for frequency-adjustable, comprising:

One resonant element, for disc, annular or symmetric polygonal structure, its center is vibration displacement node, and this resonant element is positioned at the support anchor points support of displacement node by one, and the surface of this resonant element is provided with multiple microstructure area and multiple without microstructure area; Micro-structural on described resonant element distributes along the radius even circumferential that waits of resonant element, micro-structural on this resonant element is aperture or dentalation, by changing the relative position of micro-structural and drive electrode, to encourage different resonance modes, thus obtain different rate-adaptive pacemaker, change the number of micro-structural, shape size and the position in resonant element, thus obtain different frequency-tuning ranges;

Multiple electrode, it is positioned at periphery or the top of resonant element, and be corresponding in turn to described microstructure area on resonant element and described without microstructure area, have a gap between each electrode, each electrode directly contacts with between resonant element or has a gap.

2. the MEMS resonator of frequency-adjustable according to claim 1, wherein the material of resonant element is silica-base material, piezoelectric or sapphire.

3. the MEMS resonator of frequency-adjustable according to claim 1, wherein electrode material is metal or doped semiconductor materials.

4. the MEMS resonator of frequency-adjustable according to claim 1, the gap wherein between electrode and resonant element is that air is filled or solid state medium is filled or air and solid state medium are filled jointly.