Modeling of the terminating-type power sensors fabricated by GaAs MMIC process

Abstract

In this paper, a two-dimensional (2D) model of the terminating-type power sensor is established under different input powers. The 2D heat transfer equation is applied to describe the temperature distribution, and Fourier series is used to obtain the solution based on the boundary conditions. In order to demonstrate the validity of the 2D model, finite-element method (FEM) simulation using ANSYS software was performed. The sensitivity from the 2D model and FEM is 0.25 mV mW−1 and 0.28 mV mW−1 respectively, while the sensitivity from the 1D model is 0.34 mV mW−1, which indicates that the presented 2D model is closer to the simulation than the 1D model. The terminating-type power sensor was designed and fabricated by MEMS technology and the GaAs MMIC process. The measured return loss is less than −26 dB for a frequency up to 10 GHz. The power measurement was performed and a good linearity of the output thermovoltage with respect to the input power is obtained. The measured sensitivity is close to 0.26 mV mW−1, 0.23 mV mW−1 and 0.16 mV mW−1 at 0.1, 1 and 10 GHz, respectively. Moreover, the frequency dependence measurement demonstrates that the measured thermovoltage decreases with increasing the frequency. The measurements demonstrate that the measured results agree with the presented 2D model for low frequency while the measured thermovoltage deviates from the expectation at high frequency. The reason is that the electromagnetic coupling loss of the coplanar waveguide and the parasitic loss of the load resistor become higher at high frequency.