MEMS微波功率传感器的系统级建模

System-Level Modeling of MEMS Microwave Power Sensor

提出了一种基于力-电和热-电原理的MEMS微波功率传感器,并依次对基于力-电转换原理的电容式MEMS微波功率传感器和基于热-电转换原理的热电式MEMS微波功率传感器进行建模。其一是通过采用挠度方程对力-电转换原理部分的固支梁建立力-电模型;二是通过采用热传导方程对热-电转换原理部分的温度分布建立二维热-电模型。最后将微波功率等效为均方根电压,以固支梁形变量为线索串联起力-电和热-电转换原理部分,研究微波功率、力-电转换原理部分的固支梁形变以及热-电转换原理部分的热电势之间关系,进而得到包含多物理场的系统级模型。对于电容式传感器,解析模型仿真结果与HFSS仿真结果具有较好的一致性,验证了其模型的有效性;而对于热电式传感器,衬底膜的厚度越薄,热电堆的冷热两端温差越高,进而输出热电势越大。结果表明,该MEMS微波功率传感器在30 GHz~35 GHz时插入损耗S_(11)在-0.1 dB~-0.3 dB范围内,反射损耗S_(11)小于-18 dB;当输入微波功率分别为160 mW和320 mW时,热电势在32 GHz时分别为42.41 mV和84.85 mV,在40 GHz时分别为40.03 mV和79.11 mV。

A MEMS microwave power sensor based on the principle of force-electricity and thermo-electricity is proposed, and the model of the capacitive MEMS microwave power sensor based on the principle of force-electricity conversion and the thermoelectric MEMS microwave power sensor based on the principle of thermo-electricity in turn is studied. One is to establish a force-electricity model by using the deflection equation for the fixed-fixed beam of the force-electricity conversion part;the other is to establish a two-dimensional thermo-electricity model by using the heat conduction equation for the temperature distribution of the heat-electricity conversion part. Finally, the microwave power is equivalent to the root mean square voltage, and the force-electricity and thermo-electricity conversion parts are connected in series with the fixed-fixed beam deformation as a clue. The relationship between the microwave power, the deformation of fixed-fixed beam in the force-electricity conversion principle part and the thermovoltage of the thermo-electricity conversion principle part is studied, and then a system-level model containing the multiphysics is obtained. For the capacitive sensor, the analytical model simulation results are in good agreement with the HFSS simulation results, thus verifying the validity of the model. For the thermoelectric sensor, the thinner the thickness of the substrate membrane is, the higher the temperature difference between the hot and cold ends of the thermopile is, and the larger the output thermovoltage is. The results of the MEMS microwave power sensor show that the insertion loss S_(11)is in the range of-0.1 dB~-0.3 dB,and the reflection loss S_(11)is less than-18 dB. When the microwave power is 160 mW and 320 mW,the thermovoltage is 42.41 mV and 84.85 mV at 32 GHz, and 40.03 mV and 79.11 mV at 40 GHz, respectively.