A Novel Real-Time Self-Monitoring RF MEMS Power Sensor for 0.1-30 GHz Applications

This letter proposes a new sensor for real-time monitoring of signal power based on radio frequency microelectromechanical systems (RF MEMS) technologies for long-term reliability applications, resulting in a bandwidth of 0.1-30 GHz, a return loss of less than -12.3 dB, and a sensitivity of more than 52.8 mu V/mW. This sensor is based on the conversion principle of RF power-heat-electricity and has the ability to self-monitor all resistors in real time. The self-monitoring is achieved by constructing an additional thermoelectric power sensor and a voltage divider circuit. It is fabricated on a GaAs RF monolithic integrated circuit and MEMS process. The measured return loss of the self-monitoring sensor is less than -12.3 dB up to 30 GHz. The experimental results show that the sensor features a sensitivity of 214.0, 171.4, 91.0, and 52.8 mu V/mW at 5, 10, 20, and 30 GHz, respectively. A linearity of 99.0% is obtained for the output response. Also, during the self-monitoring operation, the influence of the bias voltage on the sensing results can be minimized via data post processing. Based on the measured voltage divider ratio, the resistance of the load resistors is shown to match well with the designed value.