LTCC-Based Fluidic Tuners for Low Microwave Frequency Reconfigurable Circuits

This article presents a frequency reconfigurable RF impedance tuner using eight cascaded fluidic cells to cover the frequency band [0.9, 2.4] GHz. The tuner is made of eight fluidic fillable cavities on top of a coplanar waveguide transmission line in a single low-temperature cofired ceramic (LTCC) substrate. Each cavity is either kept empty or filled with deionized (DI) water to alter the substrate's permittivity and so change the tuner's response. Closed-form expressions are derived and used to dimension the tuner's individual cells, while 3-D field simulations are used to complete the design of a single cell and an entire eight-cell tuner. Both components are fabricated, and good agreement between simulation and measured is observed. The fabricated tuner is used to build a fluidic reconfigurable RF amplifier.