Sensitivity of MEMS microwave power sensor with the length of thermopile based on Fourier equivalent model

A Fourier equivalent model is introduced to research the thermal transfer behavior of a terminating-type MEMS microwave power sensor. The fabrication of this MEMS microwave power sensor is compatible with the GaAs MMIC process. Based on the Fourier equivalent model, the relationship between the sensitivity of a MEMS microwave power sensor and the length of thermopile is studied in particular. The power sensor is measured with an input power from 1 to 100 mW at 10 GHz, and the measurement results show that the power sensor has good input match characteristics and high linearity. The sensitivity calculated from a Fourier equivalent model is about 0.12, 0.20 and 0.29 mV/mW with the length at 40, 70 and 100 μm, respectively, while the sensitivity of the measurement results is about 0.10, 0.22 and 0.30 mV/mW, respectively, and the differences are below 0.02 mV/mW. The sensitivity expression based on the Fourier equivalent model is verified by the measurement results.