Liquid-based Tunable Loaded-Line Phase Shifter

This paper presents the design and evaluation of a liquid-based tunable loaded-line phase shifter. Its concept exploits the intrinsic dielectric characteristic of liquids to achieve tunability. This proof of concept benefits from the combination of high frequency microtechnologies and microfluidics capabilities. Two different liquids, ethanol and silicon-oil, have been evaluated. The fabricated circuit exhibits low losses of 0.54 dB at 20 GHz, moderate figure of merit about 10 degrees/dB and very broadband capabilities as the differential time delay is close to 0.73 ps up to 40 GHz.