A Sandwich-Type Thermoelectric Microwave Power Sensor for GaAs MMIC-Compatible Applications

This letter presents a sandwich-type nonmicroelectromechanical system (MEMS) thermoelectric microwave power sensor, which is based on the conversion principle of microwave power-heat-electricity. To reduce heat loss, a thermopile is designed to lie beneath two matching load resistors, electrically isolated by a dielectric layer. The design enables this sensor to eliminate the need for MEMS technology. To verify the design validity, the sandwich-type non-MEMS microwave sensor is fabricated together with a MEMS sensor. This improved sandwich-type sensor offers compatibility with the GaAs monolithic microwave integrated circuit technology. Experiments show that these sensors produce reflection losses of less than -20 dB up to 20 GHz. At 1, 10, and 20 GHz, the measured average sensitivities are ~101, 71.7, and 54.1μV^-1·mW for the traditional MEMS sensor and approximately 130.2, 92.3, and 66.8μV^-1·mW for the improved non-MEMS sensor, respectively, with good linearity of the output responses.