A Directional Inline-Type Millimeter-Wave MEMS Power Sensor for GaAs MMIC Applications

This letter presents a directional inline millimeter-wave microelectromechanical systems (MEMS) power sensor with both thermoelectric and capacitive detection elements, in order to show the power transfer direction and improve the high-power detection range. In the design, a certain percentage of the incident power is extracted by a coplanar-waveguide directional coupler, and sensed in a MEMS fixed-fixed beam for the capacitive detection and in a thermopile-based sensor for the thermoelectric detection. This power sensor offers the compatible capability with the GaAs monolithic microwave integrated circuits technology. Measured reflection and insertion losses are less than -14 and 1.3 dB at 30-36 GHz, respectively. Experiments demonstrate that the thermoelectric sensor confirms the directionality of this inline sensor for the known power level with average sensitivities of ~11.30 and 1.02 μV · mW^-1 thermoelectrically at 34 GHz for two different input ports.