An 8–12 GHz microwave frequency detector based on MEMS power sensors

Abstract

An 8–12 GHz microwave frequency detector is presented, which is based on MEMS power sensors, by sensing the phase delay of two separated signals in two different tracks. The phase delay, proportional to frequency of the input microwave signal, leads to variation of the output power. Two different kinds of MEMS power sensors, a thermoelectric microwave power sensor and a MEMS capacitive power sensor, are adopted to measure the variation. The former is used for measuring the lower power while the latter for the higher one. The presented detector has been designed, optimized and fabricated successfully using the GaAs MMIC process. For the microwave signals of 10, 15 and 20 dBm, the measured result shows that the output thermovoltage decreases with the frequency based on the thermoelectric microwave power sensor and sensitivities of the detector better than 0.033, 0.110 and 0.343 µV MHz−1 are measured, respectively. Furthermore, the sensitivity of detector is directly proportional to the power of the input microwave signal. For the microwave signals of 24 dBm, the measured result shows that the capacitance decreases with the frequency based on the MEMS capacitive power sensor and the sensitivity of 0.013 fF MHz−1 is measured. The frequency measurement demonstrates the validity of the presented design.