Ultrabroadband (DC–80 GHz) RF MEMS DC/capacitive Load Shunt Switch

This study presents the design and fabrication of a novel direct current (DC)/capacitive radio frequency (RF) Micro-Electro-Mechanical Systems (MEMS) switch in the ultrabroadband range from DC to 80 GHz. This proposed RF MEMS switch consists of two arms, with one arm providing a DC loading state (S-1), whereas the second arm provides a capacitive loading state (S-2) to the ground when pull-in voltage is applied. Insertion loss less than 1.85 dB and return loss better than 10 dB are achieved in the OFF state (S-0) from DC to 80 GHz (no pull-in voltage is applied). Due to the novel design topology, this switch can act as a DC-only switch (0-17 GHz) that provides isolation better than 25 dB during the S-1 state. A capacitive-only switch (48-80 GHz) provides isolation better than 17 dB. This proposed structure can act as either DC(S1) or a capacitive (S-2) switch (17-48 GHz) and provides isolation better than 10 dB in either state. This proposed switch finds its best application in reconfigurable circuits like phase shifters due to switching between DC and capacitive loading during the On state from 17 to 48 GHz. The proposed switch's measured pull-in and lift-off voltages are 3.5 and 2.85 V, respectively.