Reliability Improvement of the Cascaded Power Sensor Based on MIM Capacitor

A reliability-enhanced power sensor is proposed based on a metal-insulator-metal (MIM) capacitor. The coupled power by the MIM capacitor is a small part and the transmitted power is most of the incident power. Hence, the transmitted power is for low power measurement while the coupled power is used as high power detection. The proposed power sensor is fabricated by a GaAs monolithic microwave integrated circuit process. The measured return loss is greater than 21 dB over the frequency band of 8-12 GHz. When the incident power increases from 1 to 100 mW, the output voltage increases linearly and the sensitivity is measured to be about 0.125 mV/mW at 8 GHz, 0.114 mV/mW at 10 GHz, and 0.109 mV/mW at 12 GHz, respectively. For the incident power from 100 to 200 mW, a part of the incident power is coupled by the MIM capacitor and the measured sensitivity is about 15.8 μV/mW at 8 GHz, 15.4 μV/mW at 10 GHz, and 15.8 μV/mW at 12 GHz, respectively.