A GaAs MMIC-based coupling RF MEMS power sensor with both detection and non-detection states

This paper first presents the detection and non-detection function of an inline RF MEMS power sensor by employing two shunt capacitive MEMS switch structures. It solves a problem that regardless of whether the power sensor needed to detect the power, a certain microwave power will always be detected, which results in the unnecessary power loss. This power sensor is based on sensing a certain percentage of the incident microwave power coupled by a MEMS membrane. The effect of an impedance matching structure for improving microwave characteristics, a capacitance compensating structure for obtaining the wideband response, and the two shunt capacitive MEMS switch structures for achieving both states conversion together associated in this sensor, on the performance of the power sensor is proposed in this paper, and verified by the simulation and measurement. This power sensor offers the compatible capability with GaAs MMIC technology. In the detection state, experiments demonstrate that the design of the improved power sensor has resulted in the reflection loss of less than −17 dB, the insertion loss of less than 0.8 dB, and the flatness of the frequency response at X-band. And a sensitivity of more than 36 μV mW−1 and a resolution of 0.316 mW are obtained at 10 GHz under the normal ambient temperature. Yet in the non-detection state, the design has resulted in the reflection loss of less than −19 dB and the insertion loss of less than 0.6 dB. The measured actuation voltage of MEMS switches is about 42 V.