Realization of a capacitive shunt RF-MEMS switch using straight flexure based non-uniform bridge structure-fabrication and characterization

Abstract

This work presents the fabrication and characterization of a capacitive switch. The switch is implemented through a non-uniform shape based bridge structure. The design uses four straight flexures attached to two wider beams which are in turn joined to a central capacitive area for realizing the switching structure. The device is fabricated using surface micromachining process with five levels of lithography. The C–V measurement of the fabricated device showed a pull-in voltage of 10.5 V. Furthermore, in order to calculate the pull-in and release time of the device, mechanical resonant frequency is also measured through laser Doppler vibrometer (LDV). The device showed the mechanical resonant frequency of 7.63 kHz, which corresponds to 76.59 µs of pull-in time and 32.76 µs of release time. Under the RF response, S-parameters are measured through the vector network analyzer (VNA). The device showed insertion better than 0.44 dB in the X-band and was better than 0.71 dB up to Ku band. The isolation was also better than 15 dB in the frequency range from 10.3 to 40 GHz.