Single-Pole Double-Thru and True Time Delay Lines in Alumina Packaging Based on RF MEMS Switches in Silicon Technology

Abstract

Packaged MEMS devices for RF applications have been mod- elled, realized and tested. In particular, RF MEMS single ohmic series switches have been obtained on silicon high resistivity substrates and they have been integrated in alumina packages to get single-pole-double-thru (SPDT) and true-time-delay-line (TTDL) configurations. For this purpose, the individual switches have been considered as the building blocks of more complicated structures, and the alumina substrate has been properly tailored in order to get the best electri-cal performances considering all the technological steps necessary for the final hybrid device. Actually, several parameters and processes have been considered for such an optimization, involving the geometry, the wire bonding and the cover to be used. Test structures with technologically actuated switches have been also manufactured in order to have the best reference result for the proposed structures. After that, the same devices have been packaged for the final test. As a result, TTDLs for wide band operation, specifically designed for the (6–18) GHz band, have been obtained, with insertion losses less than 2 dB up to 14 GHz for the short path and 3 dB for the long path (5 dB for the real device), and delay times in the order of 0.3–0.4 ns for the short path and 0.5–0.6 ns for the long path. The maximum differential delay time is in the order of 0.2 ns