Novel Concept of Microwave MEMS Reconfigurable 7X45° Multi-Stage Dielectric-Block Phase Shifter

A novel concept of ultra-broadband multi-stage digital-type microwave MEMS phase shifters with the best performance optimized for W-band applications is introduced in this paper. The relative phase shift of 45deg of a single stage is achieved by vertically moving a lambda/2-long high-resistivity silicon dielectric block above a 3D micromachined coplanar waveguide (3D CPW) by electrostatic actuation, resulting in different propagation constants of the microwave signal for the up-state and the down-state. For full 360deg phase-shift capability, seven stages are cascaded. The devices are fabricated and assembled by wafer-scale processes using bulk and surface micromachining. The measurement results of the first prototypes show that the W-band return and insertion loss of a single 45deg stage is better than -15 dB and -1.7 dB, respectively, while the 7-stage phase shifter has a return loss better than -12 dB with an insertion loss less than -4 dB. The phase shifters also perform well from 1-110 GHz with the return loss better than -10 dB, an insertion loss of less than -1.5 dB and a fairly linear phase-shift over the whole frequency range and the actuation voltage is 30 V. To the knowledge of the authors this phase shifter is better than all previous works in term of insertion loss, return loss and phase shift per losses (deg/dB) from 70-100 GHz.