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In this paper, a novel RF MEMS shunt capacitive switch with application in the Ka frequency band is proposed. The spring design and the step structure added to the beam succeeded in improving the performance of the switch and reducing the stress which results in extended life-time of the switch. Also, by optimally reducing the gap between the dielectric and the beam (without problems such as self-actuation), the actuation voltage of the switch is significantly reduced. Electromechanical and scattering parameters analysis have been done by using COMSOL Multiphysics and HFSS software, respectively. The actuation voltage of the proposed device is 9.2 V. Since the aluminum has a lower mass compared to gold, an aluminum beam has been used in the switch. Desirable scattering parameters at the resonance frequency of 33.5 GHz have been obtained which include insertion loss of − 0.3 dB and return loss of − 18 dB. The high isolation of − 57 dB verifies the improved performance of the switch. Finally, as another innovation in this paper, the effect of inductor and capacitor presence in the input of transmission line is investigated. This analysis has been done by using ADS. Results of the circuit analysis presented in this paper, help the MEMS switch designers to understand the realistic switch behavior before fabrication which considerably saves cost and time. [ABSTRACT FROM AUTHOR]

Isolation and actuation voltages are important parameters in micro-electro-mechanical switches. These parameters can be destroyed by the effect of creating bulge and erosion in the surface of the beam. In this paper, a fabrication method is proposed to create a smooth and flat beam. Additionally, using two short high impedance transmission lines, the destructive effects on the input/output matching have been reduced. S-parameters and mechanical parameters of the proposed switch are calculated by the network analyzer and laser Doppler vibrometer. According to the results obtained from the proposed switch in the C–K band, the return loss, which is less than − 20 dB, and the highest isolation value, which is equal to − 20 dB, occur at the frequency of 21 GHz. Furthermore, the insertion loss is better than − 1 dB in the full frequency band, which is very desirable. The actuation voltage and resonance frequency were obtained at 18 V and 164 kHz, respectively. Finally, four steps are proposed to optimize the actuation voltage, isolation, stress and switching time, which results in reducing the actuation voltage by 37% and the isolation will increase by 46%. Maximum stress in the initial state is 25 MPa, and decreases to 10 MPa after optimization, which increases the lifetime of the switch. [ABSTRACT FROM AUTHOR]

MEMS capacitive switches have longer lifetimes compared to other types of metal-to-metal switches, and when placed on the membrane on the transmission line, they can easily return to the up-state due to a dielectric layer. They also transmit the input signal with more power and frequency and therefore, they are better than metal-to-metal switches. In this paper, first three switches were considered as the basic structures. Then, in order to demonstrate the credibility and high quality of the simulations, the same switches were simulated. The obtained results are very close to the results of fabrication of these switches. In the next step, with the presentation of three new structures, stimulation voltage, stress, switching time and isolation were improved in four steps. The mechanical simulation of the switch was performed to determine the amount of displacement, the amount of stress and the resonant frequency using the COMSOL software. In addition, electrical simulation of the switch was performed to obtain the S-parameter using the HFSS software. The simulation results demonstrate that the isolation is 57–66 dB and the insertion loss is 0.3–2 dB in the desired frequency band (1–50 GHz). Using new spring structures, the actuation voltage was reduced from 4.8 V in basic structures (the smallest in three structures) to 2.4 V in new structures, which is considered excellent. In order to increase the lifetime of the switch, the stress in the new switches is reduced from 12 to 4.5 MPa compared to the basic switches. [ABSTRACT FROM AUTHOR]