| PhD Viva

Name of the Speaker: Mr. Anurag Swarnkar (EE16D208)
Guide: Prof. Deleep R Nair
Online meeting link: https://meet.google.com/xmo-ugaz-ana
Date/Time: 15th July 2024 (Monday), 11:00 AM
Title: Wideband capacitive and dielectric-less high breakdown voltage RF MEMS switch

Abstract :

This work presents design, fabrication and characterization of RF MEMS SPST and SPDT switches for wideband applications. Initially, a novel RF MEMS Metal-Insulator-Metal (MIM) shunt capacitive switch is presented which consists of two identical beams placed in parallel over floating metals of different lengths on the signal line of a CPW. With two beams in parallel, the effective resistance and inductance of the switch is lesser than a switch with only one beam. The decrease in resistance provides higher isolation at resonant frequency while the decrease in inductance provides higher isolation at frequencies beyond resonant frequency. While the increase in insertion loss due to two beams is insignificant, there is a substantial increase in isolation over a large band of frequency. A switch with two beams with isolation greater than 30 dB and insertion loss less than 0.5 dB in the range of 3 GHz to 30 GHz is demonstrated. Secondly, SPST and SPDT ohmic switches are designed to counter the dielectric charging issues present in the capacitive switches. Dielectric charging is a serious issue which can lead to pull-in voltage shift and eventually may lead to permanent failure of the device. Any attempt to remove the dielectric completely from the process may improve the reliability of RF MEMS switches significantly. To mitigate the impact of dielectric charging, high breakdown voltage dielectric-less cantilever beams with bump on beam (BOB) and bump on contact metal (BOC) are designed, fabricated and characterized. The optimized cantilever beam is then used to fabricate series SPST, shunt SPST and SPDT switches, respectively. The SPDT switch offers high isolation of greater than -30 dB in the range of DC to 18 GHz. Whereas insertion loss of less than -1.4 dB was achieved in the same range.