improving RF characteristics of MEMS Capacitive Shunt Switches

Ms paper presents a new RF ,HEAlS electrostatic switch with low actuation voltage. Usually, electrostatic switches with low pull-down voltage have Jarge lip-state capacitance deteriorating their RF characteristics. 711€ proposed .n~litch el?ioys good RF characteristics for a frequency band of larger than one octave, and a low (Jell/af/on voltage 0/9 va/Is. Low actuation voltage could be achieved by decreasing Ihe gap OJ' increasing the area of the beam. In both cases, the up-state capacitance enlarges deferiorating the RF characteristics, fn this work, regardless of the value of Cu. the height of the gap is chosen by considerj,lg the reliability and life cycle of the ,\wilch. Then, (he area is calculated for the chosen gap and (he desired actualion voltage, The swirch is a rr circuit consisting of two shunt ~wi{ches and a short transmission line in between {hem. The key aspect of this design is the optimization a/the length and the characteristic impedance of the line to suit fabrication constraints and d£:Jsired frequency band. The switch is simulated and its I?F characterislics evaluated. An excellent improvement of the RF characteristics a/the up-slate position is observed. For the down-state position, a superb iso/afion is observed. Copyright © 2009 Praise Worthy Prize S.r.!. ~ All rights reserved.