A GaAs MMIC-based inline RF MEMS power sensor

In order to improve microwave characteristics and the frequency response of the output thermovoltage at X-band, an inline RF MEMS power sensor with the impedance matching and compensating capacitance structures is presented in the paper and the sensor is accomplished with GaAs MMIC process. The measured results show that the reflection loss of the sensor is less than -17 dB and the insertion loss is less than 0.8 dB at X-band. A sensitivity of more than 26 ¿V·mW^-1 and a resolution of 0.316 mW are obtained at 10 GHz. The frequency response of the sensor is relatively flat, and the modulation depth under amplitude modulation (AM) signals influences the output directly. The measured mechanical resonant frequency (f_o) of the MEMS membrane is 110 kHz. In addition, the measured results show that the intermodulation (IM) power for ¿f = 80 kHz, P₁ = P₂ = 10 dBm of the signals is less than -52 dBm. And the input third-order intermodulation intercept point (IIP3) is a large value at ¿f = f_o, so the inline RF MEMS power sensor for ¿f ¿ f_o will not generate significant intermodulation distortion.