Additively Manufactured, Low Loss 20 GHz DC Contact RF MEMS Switch Using Laterally Actuated, Fix-Free Beam

This paper presents a new type of 3D printed, electrostatically actuated DC contact RF MEMS switch that is integrated within a suspended finite-ground coplanar waveguide (FG-CPW). The design, 3D printing processes, and RF characterization are detailed. In this design, CPW lines are patterned over a printed fixed-fixed beam and the RF switches in the form of a cantilever beam are laser machined within the RF signal path. Acrylonitrile butadiene styrene (ABS) and CB028 silver paste are used to fabricate the suspended CPW lines and the switch over an air cavity. Pull-in voltage in the range of 29-36 Volts along with isolation of 20 dB and insertion loss of 0.37 dB at 20 GHz are demonstrated. The proposed method of fabrication enables designs on mm-length scales with ~5 micron-level realized feature sizes, providing a unique solution for reconfigurable packaging with flexibility in terms of RF performance and actuation voltage requirements.

I. Introduction

Electrostatic radio frequency microelectromechanical systems (RF MEMS) switches are important components for microwave and millimeter-wave circuits, devices, and systems. The switches have a wide range of applications and are used in filters, phase shifters, and impedance tuners for tunable circuits in wireless communication and defense applications, such as phased arrays for radar systems [1]. RF switches can be implemented by using conventional semiconductor techniques such as positive-intrinsic-negative (PIN) diodes and field-effect-transistors (FETs), but they have inherent performance limitations in terms of insertion loss, isolation, and power consumption [2]. Thus, RF MEMS switches have been strategically designed and developed to replace PIN diodes and GaAs FET switches under certain scenarios.