Algorithm of four-resonances MEMS capacitive switch using ADI-FDTD

In order to apply micro/nano electronics technologies and Radio Frequency Micro/nano-Electro-Mechanical System (MEMS/NEMS) technologies in the Radio Frequency (RF) field to manufacture miniature, high isolation, low insertion loss, good linear characteristic and low power consumption microwave switches. Through analysis of electrics and mechanics of the RF switch, a novel MEMS four-resonance switch is presented in this paper. The actuation voltage, insertion loss and isolation of the switch are 7 V, 0.69 dB@10.4 GHz, 30.8 dB@10.4 GHz respectively. The alternating direction implicit finite-difference time-domain (ADI-FDTD) method for a full three-dimensional (3-D) wave presented is used for modeling and analyzing the micromachine switch for the first time. The numerical method is unconditionally stable. The limitation of the maximum the time-step size of the method does not depend on the Courant-Friedrich-Levy (CFL) condition, but rather on numerical errors. Therefore, the time-step size can be arbitrarily set within numerical errors when this method is used. Associated with practical model, Murpsilas superabsorbing boundary condition was developed. It has been demonstrated that, with this technique, space discretization with only a few cells per wavelength gives accurate results, leading to a reduction of CPU computation time and improvement of computation efficiency. Based on ADI-FDTD simulation techniques, a novel concept of multi-resonance switch and its equivalent circuit are proposed. Computed results shows that the multi-resonance switch not only can work in multiple frequency bands, but also has better isolation performance in lower frequency, and thus extending the application to the lower band.