Design of High Isolation and Low Actuation Voltage Ka-band Radio Frequency MEMS Capacitive Shunt Switch

Radio frequency (RF) micro electro-mechanical systems (MEMS) switches are rapidly replacing the PIN diodes and field-effect transistors (FET). Linear behavior, low power consumption, low insertion loss, high isolation, improvement power handling and etc. are benefits of MEMS switches.This paper presents a high isolation and low actuation voltage RF MEMS capacitive switch with two shunt beams for Ka -band (27- 40 GHz) applications such as in communications satellites and uplink. Simulation results using Ansoft’s high frequency simulation software (HFSS) at Ka-band shows in the down-state of switch, the isolation (S21) is -41 dB and return loss (S11) is -0.15 dB. In the up-state, the insertion loss (S21) is -0.5 dB and the return loss (S11) is -7 dB. The pull down voltage of designed switch is 1.82 V and down-state to up-state capacitance ratio (Cd/Cu=12.11pF/0.137pF) is 88.39. In this paper the Aluminum (Al) is chosen for the membrane for having low pull down voltage and silicon nitride (Si3N4) is chosen for dielectric for having faster switching speed and larger down-state capacitance. Also Barium Strontium Titanate (BST) ferroelectric thin films are used for dielectric material

Keywords:

Aluminum , Actuation voltage , Capacitive shunt switch , Isolation , Pull down voltage , Silicon nitride