Modeling and design of 5-bit X-band RF MEMS distributed phase shifter

This paper advances the equivalent-circuit model for the unit cell of RF MEMS distributed phase shifter with MAM (Metal-Air-Metal) capacitor, which could predict the performance of the unit cell accurately. Based on the equivalent-circuit model, the dependence on fabrication process of the designed unit cell of RF MEMS distributed phase shifter is reduced very much. The maximum phase deviation of the unit cell is smaller than 0.829°even when fabrication errors reached 13%. The return loss of the unit cell is below -20dB and the worst insertion loss is -0.08dB at 10GHz. The MEMS bridge with elastic bending beam is actuated with actuation voltage 20 V. By adopting a novel topology to diminish coupling of different bits, 5-bit RF MEMS distributed phase shifter results in an average return loss of 13.56 dB, an average insertion loss of 1.49 dB, an average phase deviation of 3.17° and an average relative phase error of 2.24% at 10GHz.