Pi-shaped MEMS architecture for lowering actuation voltage of RF switching

Abstract

A wide band low actuation capacitive coupling electrostatic RF MEMS switching device is presented in this paper. The device includes a pi-shaped matching architecture containing two switches connected by a high impedance short transmission line. The device can act as a switch for any desired frequency whilst requiring only 12 volts for actuation. By optimizing the length and the characteristic impedance of the transmission line, the switch can be tailored for desired frequency bands. The switch is calculated and simulated for Ka to V frequency bands demonstrating excellent improvements of RF characteristics.

Design and simulation of a high isolation RF MEMS shunt capacitive switch for C-K band

“…This loss can be ignored for high resistivity substrates. The second type of loss, affecting on the loss of the CPW is the resistivity of material due to the effect of skin depth on transmission line, because the resistance of material is increased at higher frequency [8]. The loss of metal can be ignored if the thickness of Au is more than 1.5 μm.…”

“…The operation of MEMS switch strongly depends on the frequency and approximated by Eq. (10) [6,8]. The CLR model behaves as a capacitor below the resonant frequency, as a resistor at resonant frequency and inductor above this frequency.…”

Characterization and optimization to improve uneven surface on MEMS bridge fabrication

“…The switch consists of a bridge which is suspended over a coplanar wave guide (CPW) transmission line and fixed at both ends to the ground of the CPW. In this switch, the shape and structure of the bridge membrane are critically important as they directly affect both electrical and mechanical resonant frequencies, and pull in and pull out voltage (V pull-in and V pull-out ) [3,4].…”

Low actuation-voltage shift in MEMS switch using ramp dual-pulse

“…RF MEMS switches offer low insertion loss, and extreme linearity with minimal power consumption. However, commercialization of RF MEMS switches is hindered by the need for continuing improvements in reliability and packaging such as creep of metal membrane, stiction, fatigue in membrane and dielectric charging [1,2,3,4,5,8].…”

“…By actuating the membrane suspended electrostatically, it collapses on top of the dielectric [1,2,3,4,5,6,7,8]. Due to the high actuation voltage required to actuate the switch, the electric filed across the dielectric can be higher than 10 8 -V/m causing charge to readily tunnel from top and bottom electrodes into the dielectric which leads to an accumulation of trapped charge ( Fig.…”