Monolithically Integrated Multiport RF MEMS Switch Matrices

The design methodology and performance of a miniature-size monolithically integrated RF microelectro-mechanical systems switch matrix is reported. The switch matrix has the form a of cross-bar configuration that can be easily expanded to realize a large size switch matrix. Three single-pole single-throw RF switches coupled to coplanar waveguide transmission lines are employed to construct the unit cell with dimensions of only 320 × 320 ¿m
²
. The compact design of the proposed cell permits the high frequency operation of large switching networks. A six-mask fabrication process has been developed to construct the entire structure on a single side of the wafer. The impact of bias line resistance on the RF performance and the switching speed of the devices were studied. An excellent RF performance is achieved for a fabricated 4×4 switch matrix using high-resistive phosphorous-doped hydrogenated amorphous silicon semiconductor as the material of choice for the biasing lines. Over a frequency range from DC to 40 GHz, the worstcase measured results obtained for the insertion loss, return loss, and isolation are -1.8, -17, and 26 dB, respectively. A wide-band operation is predicted for an 8 × 8 switch matrix version constructed from 64 switching units.