Reconfigurable MEMS latching-type capacitors for high power applications

Abstract

This paper reports the design and characterization of two reconfigurable MEMS discrete capacitor banks for high power and low frequency applications. The first design is a 3-bit capacitor bank built using three parallel-connected series-switched comb-drive capacitors with appropriately scaled values. The second design is a compact discretized comb-drive varactor that can be operated as 2-bit or 3-bit capacitor bank depending on the number of latched states. Both devices are demonstrated using the METALMUMP process where 20 µm-thick plated nickel is the only structural and metal layer. The MEMS switches use thermal actuation with chevron actuator design. This allows for large displacements at relatively low actuation voltages. Using mechanical latching for both designs, the switch reconfiguration energy is minimized. The relatively very high mechanical stiffness inherent to both thermal actuator designs provides an excellent immunity to self-actuation at high RF power levels. The proposed MEMS switches are capable of operating under low-pressure conditions (e.g. in a package), without degradation of their thermo-mechanical performance.