Zhang Zhiqiang, Liao Xiaoping
Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China.
Sensors (Basel). 2017 Jun 17;17(6):1426. doi: 10.3390/s17061426.
To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n⁺ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than -17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 V/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 V/mW for the sensor with the thermal slug and the back cavity, respectively.
为实现射频（RF）功率检测、增益控制和电路保护，本文提出了基于双热流路径的n⁺ 砷化镓/金锗镍 - 金热电偶型射频微机电系统（MEMS）功率传感器。这些传感器利用射频功率 - 热 - 电压的转换原理，在射频功率变化时获得热电压。为提高传热效率和灵敏度，设计了两种热传导路径结构：一种是在两个负载电阻和热电偶的热端之间放置金的热块；另一种是通过MEMS技术制造背腔，在电阻和热端下方形成衬底膜。改进后的传感器采用砷化镓单片微波集成电路（MMIC）工艺制造。实验表明，这些传感器在高达12 GHz的频率下反射损耗小于 -17 dB。对于带有热块的传感器，在1、5和10 GHz时测得的灵敏度分别约为63.45、53.97和44.14 V/mW；对于带有热块和背腔的传感器，在相同频率下测得的灵敏度分别约为111.03、94.79和79.04 V/mW。
