An Inline Insertion Microwave MEMS Power Sensor Based on GaAs MMIC Technology with Ultra Reflection Losses

This paper proposes an inline insertion microwave microelectromechanical systems (MEMS) power sensor based on measuring the power dissipated by intrinsic ohmic losses of a coplanar waveguide (CPW) signal line by thermopiles. In order to achieve ultra reflection losses, cold junctions of the thermopiles are covered with the CPW ground lines for depressing electromagnetic coupling effects and serving as hot sink. To increase the sensitivity, the CPW ground lines are suspended above hot junctions of the thermopiles for reducing thermal losses and the CPW dimension near the thermopiles is designed to increase the temperature of the hot junctions. This sensor is completely compatible with the GaAs monolithic microwave integrated circuits (MMIC) technology. Experiments show that this optimized power sensor has resulted in reflection losses of less than -24.3 dB up to 26 GHz, with insertion losses of less than 0.37 dB. For the input power of 0.5-300 mW, the good linearity of the output response is obtained and average sensitivities are more than 6.26 and 8.21 mV/W at 2 and 20 GHz, respectively.