CN115932323A - MEMS resonant accelerometer based on high-order synchronization - Google Patents
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Abstract
Translated fromChinese
Description
Translated fromChinese技术领域technical field
本发明设计MEMS技术领域，特别设计一种基于高阶同步的MEMS谐振式加速度计。The invention relates to the technical field of MEMS, and especially designs a MEMS resonant accelerometer based on high-order synchronization.
背景技术Background technique
MEMS((Micro-Electro-Mechanical System)加速度传感器因其体积小、能耗低、响应快等优点被广泛应用于各个行业。MEMS加速度计采用的原理是外界加速度作用在敏感质量块上，导致与敏感质量块相连接的谐振梁的固有频率发生变化，通过检测谐振器频率的改变量来反推加速度的大小。对于一般的结构，通过改变敏感质量块的大小、谐振梁的长短来增加待测加速度引起的频率改变。但受限于材料本身的属性和加工工艺的限制，该方法对灵敏度的提升有限。MEMS ((Micro-Electro-Mechanical System) acceleration sensors are widely used in various industries due to their small size, low energy consumption, and fast response. The principle of MEMS accelerometers is that external acceleration acts on the sensitive mass, resulting in The natural frequency of the resonant beam connected to the sensitive mass changes, and the magnitude of the acceleration is reversed by detecting the change in the frequency of the resonator. For general structures, the size of the sensitive mass and the length of the resonant beam are increased to increase the Frequency changes caused by acceleration. However, limited by the properties of the material itself and the limitations of the processing technology, this method has limited improvement in sensitivity.
发明内容Contents of the invention
本发明为解决上述问题，提供了一种基于高阶同步的MEMS谐振式加速度计，利用同步模块，将加速度传感器的灵敏度提高了9倍，同时对稳定性提高了3倍。In order to solve the above problems, the present invention provides a MEMS resonant accelerometer based on high-order synchronization. Using a synchronization module, the sensitivity of the acceleration sensor is increased by 9 times, and the stability is increased by 3 times.
为实现上述目的，本发明采用的技术方案如下：To achieve the above object, the technical scheme adopted in the present invention is as follows:
一种基于高阶同步的MEMS谐振式加速度计，包括：A MEMS resonant accelerometer based on high-order synchronization, comprising:
低频传感模块，其用于将外界加速度信息转化为低频谐振梁的振动信号；A low-frequency sensing module, which is used to convert external acceleration information into a vibration signal of a low-frequency resonant beam;
同步模块，其包含低频同步电路和高频检测电路，所述的低频同步电路用于将低频传感模块中低频谐振梁的振动信号转化为激励信号施加给高频耦合模块中的高频谐振盘，使高频谐振盘与低频谐振梁的振动频率耦合同步；所述的高频检测电路用于检测高频谐振盘的振动信号，根据高频谐振盘的振动频率变化计算外界加速度大小；A synchronization module, which includes a low-frequency synchronization circuit and a high-frequency detection circuit, and the low-frequency synchronization circuit is used to convert the vibration signal of the low-frequency resonant beam in the low-frequency sensing module into an excitation signal and apply it to the high-frequency resonant disk in the high-frequency coupling module , so that the vibration frequency coupling of the high-frequency resonant plate and the low-frequency resonant beam is synchronized; the high-frequency detection circuit is used to detect the vibration signal of the high-frequency resonant plate, and calculate the external acceleration according to the change of the vibration frequency of the high-frequency resonant plate;
高频耦合模块，其用于通过高频谐振盘放大低频传感模块中的振动信号。The high-frequency coupling module is used to amplify the vibration signal in the low-frequency sensing module through the high-frequency resonant disk.
进一步地，所述的低频传感模块包括低频谐振梁、低频第一激励模块、低频第二激励模块和敏感质量块；Further, the low-frequency sensing module includes a low-frequency resonant beam, a low-frequency first excitation module, a low-frequency second excitation module, and a sensitive mass;
所述的低频谐振梁一端与第三锚点固定连接，第三锚点上溅射得有第三金属电极层，用于对低频谐振梁施加电压；低频谐振梁另一端与敏感质量块固接；One end of the low-frequency resonant beam is fixedly connected to the third anchor point, and a third metal electrode layer is sputtered on the third anchor point for applying voltage to the low-frequency resonant beam; the other end of the low-frequency resonant beam is fixedly connected to the sensitive mass ;
所述的低频第一激励模块为由第一受激梳齿电极板与第一激励电极板组成的梳齿形电容结构，所述的第一激励电极板与第一锚点固接，所述的第一锚点上溅射有第一金属电极层；第一受激梳齿电极板固定在低频谐振梁一侧；The low-frequency first excitation module is a comb-shaped capacitive structure composed of the first stimulated comb-tooth electrode plate and the first excitation electrode plate, the first excitation electrode plate is fixedly connected to the first anchor point, and the The first metal electrode layer is sputtered on the first anchor point; the first stimulated comb-teeth electrode plate is fixed on one side of the low-frequency resonant beam;
所述的低频第二激励模块为由第二受激梳齿电极板与第二激励电极板组成的梳齿形电容结构，所述的第二激励电极板与第二锚点固接，所述的第二锚点上溅射有第二金属电极层；第二受激梳齿电极板固定在低频谐振梁另一侧。The low-frequency second excitation module is a comb-shaped capacitive structure composed of a second stimulated comb-teeth electrode plate and a second excitation electrode plate, the second excitation electrode plate is fixedly connected to the second anchor point, and the A second metal electrode layer is sputtered on the second anchor point; the second stimulated comb-teeth electrode plate is fixed on the other side of the low-frequency resonant beam.
进一步地，所述的低频谐振梁长为500～600微米，宽为4～6微米。Further, the low-frequency resonant beam has a length of 500-600 microns and a width of 4-6 microns.
进一步地，所述的低频同步电路包括同步开关、第一运算放大器、第一带通滤波器、第一移相器、第一比较仪、第一频率计数器；Further, the low-frequency synchronous circuit includes a synchronous switch, a first operational amplifier, a first band-pass filter, a first phase shifter, a first comparator, and a first frequency counter;
所述的第一运算放大器的输入端连接第二锚点上的第二金属电极层，第一运算放大器的输出端经第一带通滤波器、第一移相器后连接第一比较仪的输入端，第一比较仪的第一输出端连接第一锚点上的第一金属电极层，第一比较仪的第二输出端通过同步开关连接到第一频率计数器，第一频率计数器将处理后的振动信号转化为激励信号传入高频耦合模块。The input end of the first operational amplifier is connected to the second metal electrode layer on the second anchor point, and the output end of the first operational amplifier is connected to the first comparator after passing through the first bandpass filter and the first phase shifter. The input terminal, the first output terminal of the first comparator is connected to the first metal electrode layer on the first anchor point, the second output terminal of the first comparator is connected to the first frequency counter through a synchronous switch, and the first frequency counter will process The final vibration signal is converted into an excitation signal and transmitted to the high-frequency coupling module.
进一步地，所述的高频耦合模块包括高频第一激励模块、高频第二激励模块、高频第三激励模块、高频第四激励模块和高频谐振盘；Further, the high-frequency coupling module includes a high-frequency first excitation module, a high-frequency second excitation module, a high-frequency third excitation module, a high-frequency fourth excitation module, and a high-frequency resonant disk;
所述的高频谐振盘通过四周均布的第四锚点、第五锚点、第六锚点、第七锚点固定，至少一个锚点上溅射有金属电极层；The high-frequency resonant disk is fixed by the fourth anchor point, the fifth anchor point, the sixth anchor point, and the seventh anchor point uniformly distributed around, and at least one anchor point is sputtered with a metal electrode layer;
所述的高频第一激励模块、高频第二激励模块、高频第三激励模块、高频第四激励模块分别位于高频谐振盘四周的两两锚点之间。The high-frequency first excitation module, the high-frequency second excitation module, the high-frequency third excitation module, and the high-frequency fourth excitation module are respectively located between two anchor points around the high-frequency resonant disk.
进一步地，所述的高频第一激励模块、高频第二激励模块、高频第三激励模块、高频第四激励模块均由高频激励电极板和高频锚点构成，所述的高频激励电极板一侧与高频谐振盘的形状贴合，间距为1-4微米；高频激励电极板另一侧与高频锚点连接，所述的高频锚点上溅射有金属电极层。Further, the high-frequency first excitation module, the high-frequency second excitation module, the high-frequency third excitation module, and the high-frequency fourth excitation module are all composed of high-frequency excitation electrode plates and high-frequency anchor points. One side of the high-frequency excitation electrode plate fits the shape of the high-frequency resonant disk with a distance of 1-4 microns; the other side of the high-frequency excitation electrode plate is connected to the high-frequency anchor point, and the high-frequency anchor point is sputtered with metal electrode layer.
进一步地，所述的高频检测电路包括第二运算放大器、第二带通滤波器、第二移相器、第二比较仪、第二频率计数器、频谱分析仪；Further, the high-frequency detection circuit includes a second operational amplifier, a second band-pass filter, a second phase shifter, a second comparator, a second frequency counter, and a spectrum analyzer;
所述的第二运算放大器的输入端连接高频第二激励模块中的高频锚点的金属电极层，第二运算放大器的输出端经第二带通滤波器、第二移相器后连接第二比较仪的输入端，第二比较仪的第一输出端分别连接频谱分析仪和第二频率计数器，第二比较仪的第二输出端连接高频第四激励模块中的高频锚点的金属电极层。The input end of the second operational amplifier is connected to the metal electrode layer of the high-frequency anchor point in the high-frequency second excitation module, and the output end of the second operational amplifier is connected to the second band-pass filter and the second phase shifter. The input terminal of the second comparator, the first output terminal of the second comparator are respectively connected to the spectrum analyzer and the second frequency counter, and the second output terminal of the second comparator is connected to the high frequency anchor point in the high frequency fourth excitation module metal electrode layer.
进一步地，所述的高频谐振盘半径为900～1200微米。Further, the radius of the high-frequency resonant disk is 900-1200 microns.
进一步地，所述的低频同步电路将处理后的振动信号转化为激励信号后施加在第一或第三激励模块中的高频锚点的金属电极层。Further, the low-frequency synchronization circuit converts the processed vibration signal into an excitation signal and applies it to the metal electrode layer of the high-frequency anchor point in the first or third excitation module.
进一步地，所述的低频谐振梁与高频谐振盘的一阶特征频率比为1:9。Further, the first-order characteristic frequency ratio of the low-frequency resonant beam and the high-frequency resonant disk is 1:9.
有益效果：本发明提供的一种基于高阶同步的MEMS谐振式加速度计，具有以下有益效果：Beneficial effects: a MEMS resonant accelerometer based on high-order synchronization provided by the present invention has the following beneficial effects:
(1)本发明利用同步效应使低频谐振梁1-1与高频谐振盘3-1达到1：9的内共振，并且相位上达成同步，使得以低频谐振梁1-1为加速度传感器的元件灵敏度提高了9倍，并且稳定性提高了3倍。(1) The present invention utilizes the synchronous effect to make the low-frequency resonant beam 1-1 and the high-frequency resonant plate 3-1 reach an internal resonance of 1:9, and achieve synchronization in phase, so that the low-frequency resonant beam 1-1 is used as an element of the acceleration sensor Sensitivity increased by a factor of 9 and stability increased by a factor of 3.
(2)相比于使用平行板电容器，本发明使用梳齿形极板作为激励和检测的极板能够增强激励的强度，加强检测的灵敏度，并且能够抵消工艺误差所造成的平行板电容器的结构不对称，增强传感器的鲁棒性和工艺适应性。(2) Compared with using parallel plate capacitors, the present invention uses comb-toothed pole plates as the pole plates for excitation and detection to enhance the intensity of excitation, strengthen the sensitivity of detection, and can offset the structure of parallel plate capacitors caused by process errors Asymmetry enhances sensor robustness and process adaptability.
(3)本发明将同步信号作为电信号，能够远距离传输并且不失真，使得低频传感模块与高频耦合模块可以相距较远，使高频耦合模块在不受外界加速度影响的情况下进行测量，精度高。(3) The present invention uses the synchronous signal as an electrical signal, which can be transmitted over a long distance without distortion, so that the low-frequency sensing module and the high-frequency coupling module can be far apart, so that the high-frequency coupling module can be carried out without being affected by external acceleration. Measurement with high precision.
附图说明Description of drawings
图1为本公开实施例提供的高灵敏度MEMS谐振式加速度传感器的结构示意图；FIG. 1 is a schematic structural diagram of a high-sensitivity MEMS resonant acceleration sensor provided by an embodiment of the present disclosure;
图2为低频传感模块的结构与电路示意图；Fig. 2 is a structure and circuit schematic diagram of the low-frequency sensing module;
图3为低频同步电路的电路示意图；Fig. 3 is the circuit diagram of low-frequency synchronous circuit;
图4为高频检测电路的电路示意图；Fig. 4 is the circuit diagram of high-frequency detection circuit;
图5为高频耦合模块的结构与电路示意图；Figure 5 is a schematic diagram of the structure and circuit of the high-frequency coupling module;
图6为未同步与同步状态下的Allan方差图；Fig. 6 is the Allan variance figure under unsynchronized and synchronous state;
图中：1-1低频谐振梁，1-2敏感质量块，1-3第一受激梳齿电极板，1-4第一激励电极板，1-5第二受激梳齿电极板，1-6第二激励电极板，1-7第一锚点，1-8第一金属电极层，1-9第二锚点，1-10第二金属电极层，1-11第三锚点，1-12第三金属电极层；2-1同步开关，2-2第一运算放大器，2-3第一带通滤波器，2-4第一移相器，2-5第一比较仪，2-6第一频率计数器，2-7第二运算放大器，2-8第二带通滤波器，2-9第二移相器，2-10第二比较仪，2-11频谱分析仪，2-12第二频率计数器；In the figure: 1-1 low-frequency resonant beam, 1-2 sensitive mass block, 1-3 first stimulated comb electrode plate, 1-4 first excited electrode plate, 1-5 second stimulated comb electrode plate, 1-6 second excitation electrode plate, 1-7 first anchor point, 1-8 first metal electrode layer, 1-9 second anchor point, 1-10 second metal electrode layer, 1-11 third anchor point , 1-12 the third metal electrode layer; 2-1 synchronous switch, 2-2 the first operational amplifier, 2-3 the first bandpass filter, 2-4 the first phase shifter, 2-5 the first comparator , 2-6 first frequency counter, 2-7 second operational amplifier, 2-8 second bandpass filter, 2-9 second phase shifter, 2-10 second comparator, 2-11 spectrum analyzer , 2-12 second frequency counter;
3-1高频谐振盘，3-2第四锚点，3-3第四金属电极层，3-4第五金属电极层，3-5第五锚点，3-6第六金属电极层，3-7第六锚点，3-8第七金属电极层，3-9第七锚点，3-10高频第一激励电极板，3-11高频第一金属电极层，3-12高频第一锚点，3-13高频第二激励电极板，3-14高频第二金属电极层，3-15高频第二锚点，3-16高频第三激励电极板，3-17高频第三金属电极层，3-18高频第三锚点，3-19高频第四激励电极板，3-20高频第四金属电极层，3-21高频第四锚点。3-1 high-frequency resonant disk, 3-2 fourth anchor point, 3-3 fourth metal electrode layer, 3-4 fifth metal electrode layer, 3-5 fifth anchor point, 3-6 sixth metal electrode layer , 3-7 sixth anchor point, 3-8 seventh metal electrode layer, 3-9 seventh anchor point, 3-10 high-frequency first excitation electrode plate, 3-11 high-frequency first metal electrode layer, 3- 12 high-frequency first anchor point, 3-13 high-frequency second excitation electrode plate, 3-14 high-frequency second metal electrode layer, 3-15 high-frequency second anchor point, 3-16 high-frequency third excitation electrode plate , 3-17 high-frequency third metal electrode layer, 3-18 high-frequency third anchor point, 3-19 high-frequency fourth excitation electrode plate, 3-20 high-frequency fourth metal electrode layer, 3-21 high-frequency first Four anchor points.
具体实施方式Detailed ways
为使本发明的目的、技术方案和优点更加清楚明白，以下结合具体实施例，并参照附图，对本发明进一步详细说明。In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.
如图1所示，本发明提供了一种基于高阶同步的MEMS谐振式加速度计，包含低频传感模块、同步模块、高频耦合模块。As shown in FIG. 1 , the present invention provides a MEMS resonant accelerometer based on high-order synchronization, which includes a low-frequency sensing module, a synchronization module, and a high-frequency coupling module.
如图2所示，所述的低频传感模块包含低频谐振梁1-1、低频第一激励模块、低频第二激励模块、敏感质量块1-2。所述的低频谐振梁1-1一端与第三锚点1-11固定连接，第三锚点1-11上溅射得有第三金属电极层1-12，用于对低频谐振梁1-1施加电压；低频谐振梁1-1另一端与敏感质量块1-2固接，当外界存在加速度时，即可由敏感质量块1-2的惯性力改变低频谐振梁1-1的谐振频率。As shown in FIG. 2 , the low-frequency sensing module includes a low-frequency resonant beam 1-1, a low-frequency first excitation module, a low-frequency second excitation module, and a sensitive mass 1-2. One end of the low-frequency resonant beam 1-1 is fixedly connected to the third anchor point 1-11, and a third metal electrode layer 1-12 is sputtered on the third anchor point 1-11, which is used to control the low-frequency resonant beam 1-11. 1. Apply voltage; the other end of the low-frequency resonant beam 1-1 is fixedly connected to the sensitive mass 1-2. When there is acceleration outside, the resonance frequency of the low-frequency resonant beam 1-1 can be changed by the inertial force of the sensitive mass 1-2.
在本发明的一项具体实施中，所述的低频第一激励模块由第一受激梳齿电极板1-3与第一激励电极板1-4组成，所述的第一激励电极板1-4与第一锚点1-7固接，所述的第一锚点1-7上溅射有第一金属电极层1-8；第一受激梳齿电极板1-3与第一激励电极板1-4均为梳齿形电极板，两者形成梳齿形电容，在静电力的作用下为低频谐振梁1-1提供外激励，使低频谐振梁1-1产生振动。In a specific implementation of the present invention, the low-frequency first excitation module is composed of a first stimulated comb electrode plate 1-3 and a first excitation electrode plate 1-4, and the first excitation electrode plate 1 -4 is fixedly connected to the first anchor point 1-7, and the first metal electrode layer 1-8 is sputtered on the first anchor point 1-7; the first stimulated comb electrode plate 1-3 is connected to the first The excitation electrode plates 1-4 are comb-shaped electrode plates, and the two form a comb-shaped capacitor, which provides external excitation for the low-frequency resonant beam 1-1 under the action of electrostatic force, so that the low-frequency resonant beam 1-1 vibrates.
低频第二激励模块由第二受激梳齿电极板1-5与第二激励电极板1-6组成，所述的第二激励电极板1-6与第二锚点1-9固接，所述的第二锚点1-9上溅射有第二金属电极层1-10；第二受激梳齿电极板1-5与第二激励电极板1-6均为梳齿形电极板，两者形成梳齿形电容，用来检测低频谐振梁1-1的振动状态并转化为电信号输出。The low-frequency second excitation module is composed of a second stimulated comb electrode plate 1-5 and a second excitation electrode plate 1-6, the second excitation electrode plate 1-6 is fixedly connected to the second anchor point 1-9, The second metal electrode layer 1-10 is sputtered on the second anchor point 1-9; the second stimulated comb-toothed electrode plate 1-5 and the second excited electrode plate 1-6 are comb-shaped electrode plates , the two form a comb-shaped capacitor, which is used to detect the vibration state of the low-frequency resonant beam 1-1 and convert it into an electrical signal for output.
所述的高频耦合模块包含高频第一激励模块、高频第二激励模块、高频第三激励模块、高频第四激励模块和高频谐振盘3-1。The high-frequency coupling module includes a high-frequency first excitation module, a high-frequency second excitation module, a high-frequency third excitation module, a high-frequency fourth excitation module and a high-frequency resonant disk 3-1.
如图5所示，所述的高频谐振盘3-1半径为900～1200微米，其上下左右分别有一个固接边长为120～150微米的正方形锚点，与硅底固接，主要起到固定作用；每一个锚点上分别溅射有金属电极层。本实施例中，从高频谐振盘3-1上方开始按照顺时针方向，将四个正方形锚点依次命名为第四锚点3-2、第五锚点3-5、第六锚点3-7和第七锚点3-9，第四锚点3-2其上溅射有第四金属电极层3-3，第五锚点3-5其上溅射有第五金属电极层3-4，第六锚点3-7其上溅射有第六金属电极层3-6，第七锚点3-9其上溅射有第七金属电极层3-8，本实施例中，在第四金属电极层3-3、第五金属电极层3-4、第六金属电极层3-6、第七金属电极层3-8中的任一个金属电极层上施加偏置电压。As shown in Figure 5, the radius of the high-frequency resonant disk 3-1 is 900-1200 microns, and there are square anchor points with fixed side lengths of 120-150 microns on the upper, lower, left and right sides respectively, which are fixed to the silicon bottom, mainly It plays a fixed role; each anchor point is sputtered with a metal electrode layer. In this embodiment, starting from the top of the high-frequency resonant disk 3-1 in a clockwise direction, the four square anchor points are named as the fourth anchor point 3-2, the fifth anchor point 3-5, and the sixth anchor point 3. -7 and the seventh anchor point 3-9, the fourth anchor point 3-2 has a fourth metal electrode layer 3-3 sputtered thereon, and the fifth anchor point 3-5 has a fifth metal electrode layer 3 sputtered thereon -4, the sixth anchor point 3-7 is sputtered with a sixth metal electrode layer 3-6, and the seventh anchor point 3-9 is sputtered with a seventh metal electrode layer 3-8. In this embodiment, A bias voltage is applied to any one of the fourth metal electrode layer 3-3, the fifth metal electrode layer 3-4, the sixth metal electrode layer 3-6, and the seventh metal electrode layer 3-8.
此外，两个高频谐振盘3-1上下左右的两两正方形锚点之间各设有一个高频激励模块，四个高频激励模块中的任一个高频激励模块用于对高频谐振盘3-1施加外激励，任一个高频激励模块用来检测高频谐振盘3-1的振动状态，以及任一个高频激励模块用来施加同步模块传递来的同步信号。本实施例中，将位于高频谐振盘3-1左上、右上、左下、右下位置的四个高频激励模块依次命名为高频第一激励模块、高频第二激励模块、高频第三激励模块、高频第四激励模块，其中，高频第一激励模块与高频第四激励模块用来对高频谐振盘3-1施加外激励。高频第二激励模块用来检测高频谐振盘3-1的振动状态并将其转化为电信号，用以得到待测加速度的值。高频第三激励模块用来施加同步模块传递来的同步信号，使高频谐振盘3-1与低频谐振梁1-1的振动耦合达成同步。In addition, a high-frequency excitation module is provided between the two square anchor points on the upper, lower, left, and right sides of the two high-frequency resonant disks 3-1, and any one of the four high-frequency excitation modules is used to control the high-frequency resonance The disk 3-1 applies external excitation, any one of the high-frequency excitation modules is used to detect the vibration state of the high-frequency resonant disk 3-1, and any one of the high-frequency excitation modules is used to apply the synchronization signal delivered by the synchronization module. In this embodiment, the four high-frequency excitation modules located in the upper left, upper right, lower left, and lower right positions of the high-frequency resonance plate 3-1 are named as the first high-frequency excitation module, the second high-frequency excitation module, and the second high-frequency excitation module. Three excitation modules and a fourth high-frequency excitation module, wherein the first high-frequency excitation module and the fourth high-frequency excitation module are used to apply external excitation to the high-frequency resonant disk 3-1. The high-frequency second excitation module is used to detect the vibration state of the high-frequency resonant disk 3-1 and convert it into an electrical signal to obtain the value of the acceleration to be measured. The third high-frequency excitation module is used to apply the synchronization signal transmitted by the synchronization module to synchronize the vibration coupling between the high-frequency resonant plate 3-1 and the low-frequency resonant beam 1-1.
在本发明的一项具体实施中，四个高频激励模块均由高频激励电极板和高频锚点构成，本实施例中，高频锚点为长200～300微米、宽100～150微米的长方形，与硅底固接；激励电极板与高频谐振盘的形状贴合，间距为1到4微米，高频激励电极板与长方形高频锚点通过三根梁固接。每一个高频锚点上分别溅射有金属电极层，其中高频第一锚点3-12其上溅射有高频第一金属电极层3-11，高频第二锚点3-15其上溅射有高频第二金属电极层3-14，高频第三锚点3-18其上溅射有高频第三金属电极层3-17，高频第四锚点3-21其上溅射有高频第四金属电极层3-20。In a specific implementation of the present invention, the four high-frequency excitation modules are all composed of high-frequency excitation electrode plates and high-frequency anchor points. The micron rectangle is fixed to the silicon bottom; the excitation electrode plate fits the shape of the high-frequency resonant plate with a distance of 1 to 4 microns, and the high-frequency excitation electrode plate is fixed to the rectangular high-frequency anchor point through three beams. A metal electrode layer is sputtered on each high-frequency anchor point respectively, wherein a high-frequency first anchor point 3-12 is sputtered with a high-frequency first metal electrode layer 3-11, and a high-frequency second anchor point 3-15 A high-frequency second metal electrode layer 3-14 is sputtered on it, a high-frequency third anchor point 3-18 is sputtered with a high-frequency third metal electrode layer 3-17, and a high-frequency fourth anchor point 3-21 A fourth high-frequency metal electrode layer 3-20 is sputtered thereon.
所述的同步模块包含低频同步电路和高频检测电路。The synchronization module includes a low-frequency synchronization circuit and a high-frequency detection circuit.
如图3所示，所述的低频同步电路包含：同步开关2-1、第一运算放大器2-2、第一带通滤波器2-3、第一移相器2-4、第一比较仪2-5、第一频率计数器2-6，其中，第一运算放大器2-2的输入端连接第二锚点1-9上的第二金属电极层1-10，第一运算放大器2-2的输出端经第一带通滤波器2-3、第一移相器2-4后连接第一比较仪2-5的输入端，第一比较仪2-5的第一输出端连接第一锚点1-7上的第一金属电极层1-8，第一比较仪2-5的第二输出端通过同步开关2-1连接到第一频率计数器2-6，第一频率计数器2-6将处理后的频率信号传入3-18；低频同步电路用来处理低频谐振梁1-1的振动信号并施加给高频耦合模块中的高频谐振盘3-1，使高频谐振盘3-1与低频谐振梁1-1的振动耦合同步。As shown in Figure 3, described low-frequency synchronous circuit comprises: synchronous switch 2-1, the first operational amplifier 2-2, the first band-pass filter 2-3, the first phase shifter 2-4, the first comparison Instrument 2-5, first frequency counter 2-6, wherein, the input terminal of the first operational amplifier 2-2 is connected to the second metal electrode layer 1-10 on the second anchor point 1-9, the first operational amplifier 2- The output end of 2 is connected to the input end of the first comparator 2-5 after the first bandpass filter 2-3, the first phase shifter 2-4, and the first output end of the first comparator 2-5 is connected to the first The first metal electrode layer 1-8 on an anchor point 1-7, the second output terminal of the first comparator 2-5 is connected to the first frequency counter 2-6 through the synchronous switch 2-1, the first frequency counter 2 -6 Pass the processed frequency signal to 3-18; the low-frequency synchronous circuit is used to process the vibration signal of the low-frequency resonant beam 1-1 and apply it to the high-frequency resonant plate 3-1 in the high-frequency coupling module to make the high-frequency resonance The disc 3-1 is synchronized with the vibration coupling of the low frequency resonant beam 1-1.
如图4所示，所述的高频检测电路包含：第二运算放大器2-7、第二带通滤波器2-8、第二移相器2-9、第二比较仪2-10、第二频率计数器2-12、频谱分析仪2-11，其中第二运算放大器2-7的输入端连接高频第二锚点3-15上的高频第二金属电极层3-14，第二运算放大器2-7的输出端经第二带通滤波器2-8、第二移相器2-9后连接第二比较仪2-10的输入端，第二比较仪2-10的第一输出端分别连接频谱分析仪2-11和第二频率计数器2-12，第二比较仪2-10的第二输出端连接高频第四锚点3-21上的高频第四金属电极层3-20。高频检测电路用来检测高频谐振盘3-1的振动信号，得到高频谐振盘3-1的振动信息——频率和相位，进而根据频率的变化计算反推得到外界加速度的大小。As shown in Figure 4, described high-frequency detection circuit comprises: the second operational amplifier 2-7, the second bandpass filter 2-8, the second phase shifter 2-9, the second comparator 2-10, The second frequency counter 2-12, the spectrum analyzer 2-11, wherein the input end of the second operational amplifier 2-7 is connected to the high frequency second metal electrode layer 3-14 on the high frequency second anchor point 3-15, the second The output end of the two operational amplifiers 2-7 is connected to the input end of the second comparator 2-10 after the second bandpass filter 2-8, the second phase shifter 2-9, and the second comparator 2-10's first input end One output terminal is respectively connected to the spectrum analyzer 2-11 and the second frequency counter 2-12, and the second output terminal of the second comparator 2-10 is connected to the high-frequency fourth metal electrode on the high-frequency fourth anchor point 3-21 Layers 3-20. The high-frequency detection circuit is used to detect the vibration signal of the high-frequency resonant disk 3-1, obtain the vibration information of the high-frequency resonant disk 3-1—frequency and phase, and then calculate and deduce the magnitude of the external acceleration according to the change of the frequency.
在本发明的一项具体实施中，第一、二、三、四、五、六、七金属电极层由铜和铬组成的正方形，铜在下，铬在上，边长50～120微米，铜的厚度为500～600纳米，铬的厚度为20～30纳米。In a specific implementation of the present invention, the first, second, third, fourth, fifth, sixth, and seventh metal electrode layers are squares composed of copper and chromium. The thickness of the chromium is 500-600 nanometers, and the thickness of the chromium is 20-30 nanometers.
在本发明的一项具体实施中，通过调节低频谐振梁和高频谐振盘的尺寸，可以改变低频谐振梁1-1与高频谐振盘3-1的一阶特征频率比。本实施例中，低频谐振梁1-1与高频谐振盘3-1的一阶特征频率比为1：9，低频谐振梁1-1的尺寸范围为500～600微米长，4～6微米宽，高频谐振盘3-1的半径为900～1200微米；低频谐振梁和高频谐振盘的厚度均为25微米。In a specific implementation of the present invention, by adjusting the dimensions of the low-frequency resonant beam and the high-frequency resonant plate, the first-order characteristic frequency ratio of the low-frequency resonant beam 1-1 and the high-frequency resonant plate 3-1 can be changed. In this embodiment, the first-order characteristic frequency ratio of the low-frequency resonant beam 1-1 and the high-frequency resonant plate 3-1 is 1:9, and the size range of the low-frequency resonant beam 1-1 is 500-600 microns long, 4-6 microns Wide, the radius of the high-frequency resonant disk 3-1 is 900-1200 microns; the thickness of the low-frequency resonant beam and the high-frequency resonant disk are both 25 microns.
上述基于同步的高灵敏度MEMS谐振式加速度计的工作过程为：将低频传感模块中第三锚点1-11上的第三金属电极层1-12接地，使得低频谐振梁1-1与敏感质量块1-2保持0电势。在第一锚点1-7上的第一金属电极层1-8施加直流电与交流电的混合电势，由第一受激梳齿电极板1-3与第一激励电极板1-4组成的梳齿形电容器之间由于有电势差存在会产生静电力，使得低频谐振梁1-1发生振动；同样的，在第二锚点1-9上的第二金属电极层1-10施加直流电势，由第二受激梳齿电极板1-5与第二激励电极板1-6组成的梳齿形电容器之间由于有位移的变化会导致电容发生变化，在第二金属电极层1-10上引起随位移变化的交流电势，将振动信号转化成电信号，并通过同步模块中的低频同步电路输入第一频率计数器2-6，由第一频率计数器2-6中输出的电信号通过高频耦合模块中高频第三锚点3-18上的高频第三金属电极层3-17施加在高频第三激励电极板3-16上，由于高频第三激励电极板3-16与高频谐振盘3-1组成电容器，则电信号会产生静电力，施加在高频谐振盘3-1上，使高频谐振盘3-1与低频谐振梁1-1的振动耦合同步。The working process of the above-mentioned high-sensitivity MEMS resonant accelerometer based on synchronization is: ground the third metal electrode layer 1-12 on the third anchor point 1-11 in the low-frequency sensing module, so that the low-frequency resonant beam 1-1 is connected to the sensitive Mass blocks 1-2 maintain zero potential. The first metal electrode layer 1-8 on the first anchor point 1-7 applies a mixed potential of direct current and alternating current, and the comb composed of the first stimulated comb electrode plate 1-3 and the first excitation electrode plate 1-4 Due to the potential difference between the toothed capacitors, an electrostatic force will be generated, causing the low-frequency resonant beam 1-1 to vibrate; similarly, a DC potential is applied to the second metal electrode layer 1-10 on the second anchor point 1-9, resulting in The second stimulated comb-tooth electrode plate 1-5 and the comb-tooth capacitor formed by the second excitation electrode plate 1-6 will cause the capacitance to change due to the change of displacement, which will cause a change in the second metal electrode layer 1-10. The AC potential that changes with the displacement converts the vibration signal into an electrical signal, and inputs the first frequency counter 2-6 through the low-frequency synchronous circuit in the synchronization module, and the electrical signal output from the first frequency counter 2-6 is coupled by high-frequency The high-frequency third metal electrode layer 3-17 on the high-frequency third anchor point 3-18 in the module is applied on the high-frequency third excitation electrode plate 3-16, because the high-frequency third excitation electrode plate 3-16 and the high-frequency The resonant disk 3-1 forms a capacitor, and the electric signal will generate electrostatic force, which is applied to the high frequency resonant disk 3-1, so that the vibration coupling of the high frequency resonant disk 3-1 and the low frequency resonant beam 1-1 is synchronized.
所述的高频谐振盘3-1通过第四锚点3-2、第五锚点3-5、第六锚点3-7、第七锚点3-9固定，并通过第四锚点3-2上的第四金属电极层3-3施加偏置电压，通过高频第四锚点3-21上的高频第四金属电极层3-20施加交流电压，由于高频第四激励电极板3-19与高频谐振盘3-1组成电容器，二者之间会产生静电力，在静电力的作用下，高频谐振盘产生3-1振动。由于高频谐振盘3-1与低频谐振梁1-1的特征频率比为1：9，因此在发生同步时，高频谐振盘3-1的频率偏移是低频谐振梁1-1频率偏移的9倍。The high-frequency resonant plate 3-1 is fixed by the fourth anchor point 3-2, the fifth anchor point 3-5, the sixth anchor point 3-7, and the seventh anchor point 3-9, and is fixed by the fourth anchor point A bias voltage is applied to the fourth metal electrode layer 3-3 on the 3-2, and an AC voltage is applied to the high-frequency fourth metal electrode layer 3-20 on the high-frequency fourth anchor point 3-21, due to the high-frequency fourth excitation The electrode plate 3-19 and the high-frequency resonant disk 3-1 form a capacitor, and an electrostatic force is generated between them. Under the action of the electrostatic force, the high-frequency resonant disk generates 3-1 vibration. Since the characteristic frequency ratio of the high-frequency resonant disk 3-1 and the low-frequency resonant beam 1-1 is 1:9, when synchronization occurs, the frequency deviation of the high-frequency resonant disk 3-1 is equal to the frequency deviation of the low-frequency resonant beam 1-1. Shifted 9 times.
由于高频谐振盘3-1与高频第二激励电极板3-13形成电容器，在高频谐振盘3-1发生振动时，二者之间的位移会转化为电信号，电信号通过同步模块中的高频检测电路，依次经第二运算放大器2-7、第二带通滤波器2-8、第二移相器2-9、第二比较仪2-10处理后输入频谱分析仪2-11与第二频率计数器2-12。Since the high-frequency resonant disk 3-1 and the high-frequency second excitation electrode plate 3-13 form a capacitor, when the high-frequency resonant disk 3-1 vibrates, the displacement between the two will be converted into an electrical signal, and the electrical signal will be synchronized The high-frequency detection circuit in the module is input into the spectrum analyzer after being processed by the second operational amplifier 2-7, the second band-pass filter 2-8, the second phase shifter 2-9, and the second comparator 2-10 in sequence 2-11 and the second frequency counter 2-12.
当待测加速度作用时，敏感质量块1-2发生偏移，导致在低频谐振梁1-1上产生应力，使低频谐振梁1-1发生频移，低频谐振梁1-1的频率信号被低频同步电路测量传递到第一频率计数器2-6，再通过高频第三激励模块施加给高频谐振盘3-1，由于高频谐振盘3-1与低频谐振梁1-1处于同步状态，并且高频谐振盘3-1的特征频率是低频谐振梁1-1的9倍，因此高频谐振盘3-1频率偏移是低频谐振梁1-1的9倍，通过高频第二激励模块检测频率偏移即可得到外界加速度的大小，也即是高频谐振盘3-1的灵敏度提高了9倍，并且稳定性也提高了3倍。When the acceleration to be measured acts, the sensitive mass 1-2 shifts, resulting in stress on the low-frequency resonant beam 1-1, causing the frequency shift of the low-frequency resonant beam 1-1, and the frequency signal of the low-frequency resonant beam 1-1 is The measurement of the low-frequency synchronous circuit is transmitted to the first frequency counter 2-6, and then applied to the high-frequency resonant plate 3-1 through the third high-frequency excitation module, because the high-frequency resonant plate 3-1 and the low-frequency resonant beam 1-1 are in a synchronous state , and the characteristic frequency of the high-frequency resonant plate 3-1 is 9 times that of the low-frequency resonant beam 1-1, so the frequency offset of the high-frequency resonant plate 3-1 is 9 times that of the low-frequency resonant beam 1-1. The excitation module detects the frequency offset to obtain the magnitude of the external acceleration, that is, the sensitivity of the high-frequency resonant disk 3-1 is increased by 9 times, and the stability is also increased by 3 times.
为防止高频耦合模块受外界加速度的影响，可以使高频耦合模块距离低频传感模块和同步模块足够远，即远离待测加速度区域。In order to prevent the high-frequency coupling module from being affected by the external acceleration, the high-frequency coupling module can be far enough away from the low-frequency sensing module and the synchronization module, that is, away from the acceleration area to be measured.
本发明一种基于高阶同步的MEMS谐振式加速度计利用敏感质量块受到外界加速度作用产生的惯性力偏移改变低频谐振梁1-1的特征频率，在同步效应作用下，高频谐振盘3-1的特征频率为低频谐振梁1-1的9倍，因此高频谐振盘3-1的频率偏移也是低频谐振梁1-1的9倍，因此，灵敏度提高了9倍。本实施例中，对比未同步与同步状态下的Allan方差，如图6所示，图6中的(a)表示低频传感模块的测试结果，此时同步模块中的同步开关断开，测试曲线的最低点23ppb可用于表征稳定性。图6中的(b)表示高频耦合模块的测试结果，上曲线为同步模块中的同步开关闭合时的测试结果，下曲线为同步模块中的同步开关断开时的测试结果，上曲线的最低点7ppb，可以发现引入高频耦合模块后，加速度计的稳定性提高了大约3倍。A MEMS resonant accelerometer based on high-order synchronization of the present invention uses the inertial force offset generated by the sensitive mass block under the action of external acceleration to change the characteristic frequency of the low-frequency resonant beam 1-1, and under the action of the synchronization effect, the high-frequency resonant plate 3 The characteristic frequency of -1 is 9 times that of the low-frequency resonant beam 1-1, so the frequency offset of the high-frequency resonant plate 3-1 is also 9 times that of the low-frequency resonant beam 1-1, so the sensitivity is increased by 9 times. In the present embodiment, compare the Allan variance under unsynchronized and synchronous states, as shown in Figure 6, (a) in Figure 6 represents the test result of the low-frequency sensing module, at this moment, the synchronous switch in the synchronous module is disconnected, and the test The lowest point of the curve, 23ppb, can be used to characterize stability. (b) in Fig. 6 represents the test result of the high-frequency coupling module, the upper curve is the test result when the synchronous switch in the synchronous module is closed, the lower curve is the test result when the synchronous switch in the synchronous module is disconnected, and the upper curve is the test result when the synchronous switch in the synchronous module is off. The lowest point is 7ppb. It can be found that after introducing the high frequency coupling module, the stability of the accelerometer is increased by about 3 times.
以上所述的具体实施例，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施例而已，并不用于限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。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 within the protection scope of the present invention.
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