A Novel Inline Near-Zero Thermopile RF MEMS Power Sensor

This paper presents a novel single-chip integrated inline thermoelectric MEMS sensor for measuring the forward and reverse RF power. The sensor operates on the principle of RF power-heat-electricity. It utilizes all-passive structures for near-zero power consumption, with a wide bandwidth (22-30 GHz), high power detection capability (600 mW) and small chip size (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1640\times 910~\mu $ </tex-math></inline-formula>m2). A MEMS coupling structure with suspended beams is designed to be broadband and miniaturized, while two MEMS sensing structures with optimized thermopiles are designed for high sensitivity and high power detection. This MEMS sensor is fabricated using the GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show a reflection loss of less than −10.40 dB, and an insertion loss of better than −1.55 dB. Linearity of 98.8% is obtained. At 26, 27 and 28 GHz, measured sensitivities are about 4.10, 4.57 and 4.61 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>V/mW for the forward detection, and 0.32, 0.83 and 1.10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>V/mW for the reverse detection, respectively. The ratios of these sensitivities produce a maximum at the center frequency of interest. [2024-0095]