Design and simulation of a novel RF MEMS shunt capacitive switch with low actuation voltage and high isolation

Abstract

This paper presents a new RF MEMS capacitive shunt switch with low voltage, low loss and high isolation for K-band applications. In this design, we have proposed the step structure to reduce the air gap between the bridge and the signal line, thus the actuation voltage is reduced to 2.9 V. Furthermore, to reach more isolation, we used aluminum nitride (AlN) as a dielectric layer instead of conventional dielectric materials such as $Sio_{2}$ and $Si_{3} N_{4}$ which has more $\varepsilon_{r}$ led to increase the down-state capacitance and increase the isolation of switch. Moreover, to reach more isolation, a kind of meander have designed to increase the inductance of switch, therefore, the resonant frequency is shifted to the desired frequency band. The results show that the switch in up position involve $S_{11}$ less than −10 dB from 1 to 40 GHZ and $S_{21}$ more than −0.72 dB from 1 to 22 GHZ. In down state, switch has an excellent isolation at the frequency range of K-band. The maximum isolation of −58 dB is obtained at resonance frequency of 27 GHZ.