Distributed MEMS Tunable Phase Shifters on CMOS Technology for Millimeter Wave Frequencies

The concept of a slow-wave MEMS tunable phase shifter that can be fabricated using the CMOS back-end and an additional maskless post-process etch is presented. The tunable phase shifter concept is formed by a conventional slow-wave transmission line. The metallic ribbons that form the patterned floating shield of this type of structure are released to allow motion when a control voltage is applied, which changes the characteristic impedance and the phase velocity. For this device a quality factor greater than 32 can be maintained, resulting in a figure of merit on the order of 0.85 dB/360° and a total area smaller than 0.065 mm for a 60-GHz working frequency.