Zhang Zhiqiang, Ma Yao
Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China.
College of Field Battle Engineering, People's Liberation Army University of Science and Technology, Nanjing 210007, China.
Micromachines (Basel). 2018 Mar 29;9(4):154. doi: 10.3390/mi9040154.
Wideband and low-loss microwave power measurements are becoming increasingly important for microwave communication and radar systems. To achieve such a power measurement, this paper presents the design and measurement of wideband DC-25 GHz and low-loss MEMS thermoelectric power sensors with a floating thermal slug and a reliable back cavity. In the sensors, the microwave power is converted to thermovoltages via heat. The collaborative design of the thermal slug and the back cavity, i.e., two thermal flow paths, is utilized to improve the efficiency of heat transfer and to ensure reliable applications. These sensors are required to operate up to 25 GHz. In order to achieve low microwave losses at the bandwidth, the floating thermal slug is designed instead of the grounded one. The effects of the floating slug on the reflection losses are analyzed by the simulation. The fabrication of these sensors is completed by GaAs monolithic microwave integrated circuits (MMIC) and micro-electro-mechanical systems (MEMS) technology. Measured reflection losses are less than -25.6 dB up to 12 GHz and -18.6 dB up to 25 GHz. The design of the floating thermal slug reduces the losses, which is equivalent to improving the sensitivity. At 10 and 25 GHz, experiments exhibit that the sensors result in sensitivities of about 51.13 and 35.28 μV/mW for the floating slug and 81.68 and 55.20 μV/mW for the floating slug and the cavity.
宽带和低损耗微波功率测量对于微波通信和雷达系统变得越来越重要。为实现这种功率测量，本文介绍了具有浮动热块和可靠背腔的宽带直流至25GHz低损耗MEMS热电功率传感器的设计与测量。在这些传感器中，微波功率通过热转换为热电压。利用热块和背腔的协同设计，即两条热流路径，来提高热传递效率并确保可靠应用。这些传感器要求工作频率高达25GHz。为了在该带宽上实现低微波损耗，设计了浮动热块而非接地热块。通过仿真分析了浮动热块对反射损耗的影响。这些传感器采用砷化镓单片微波集成电路（MMIC）和微机电系统（MEMS）技术制造。在高达12GHz时测量的反射损耗小于-25.6dB，在高达25GHz时小于-18.6dB。浮动热块的设计降低了损耗，这等同于提高了灵敏度。在10GHz和25GHz时，实验表明对于浮动热块，传感器的灵敏度约为51.13和35.28μV/mW，对于浮动热块和腔体，传感器灵敏度约为81.68和55.20μV/mW。
