A novel capacitive RF-MEMS switch for multi-frequency operation

This paper reports a novel capacitive RF-MEMS switch. The presented device has frequency reconfigurable characteristics and thus can be used in multi-band wireless systems. The switch is realized through two non-uniform cantilevers with dissimilar shape. The structure of the cantilevers is kept dissimilar to achieve the different value of inductance in the down-state of the device and hence the different electrical resonant frequency. Further, the proposed device has also overcome issue of shift in the isolation response caused by residual stress in switching structure and micro-roughness in the deposited SiO2 layer. The device forms a M-I-M capacitor at the central conductor of the transmission line to resolve the above cited problem and also allows the use of cantilever structures for the implementation of capacitive switches in place of conventional bridge type structures. The measured isolation response shows three optimum values of 25.40 dB, 20.44 dB, and 30.80 dB at 9.4 GHz, 11.6 GHz, and 25.2 GHz respectively. The measured insertion loss is also better than 0.41 dB up to 30 GHz. Under, mechanical characterization, cantilever with two narrow beams shows resonant frequency of 3.90 kHz and cantilever with single narrow beam shows resonant frequency of 4.66 kHz. Furthermore, the device has measured pull-in voltage which is less than 16 V.