Mechanically Coupled Low-Voltage Electrostatic Resistive RF Multithrow Switch

This paper proposes an electromechanically actuated single-pole multithrow RF switch utilizing an axial force coupling mechanism among switching membranes. All switches are evenly distributed and coupled to each other with a pair of microbeams. When one membrane is switching on, the others become stiffer than before by the increased axial force. This enables the individual switch to achieve low switching-on voltage and high power handling capability at an off state simultaneously. The analytic estimation presents a 36% reduced stiffness at switching- on and a 34% increased stiffness in sustaining an off state. The topologies for both of the single pole double throws (SPDT) and single pole triple throws (SP3T) using this technique are designed and implemented. Actuation voltages are as low as 15 V for an SPDT and 20 V for an SP3T. The insertion loss and isolation among throws of the SP3T are measured to be 0.25 and 51.5 dB at 2 GHz, respectively. Significant improvement of isolation (from 37 to 45.7 dB) in the high-frequency band (at 10 GHz) proves the benefit of the proposed concept. Typical switching time of the SP3T is measured to be 7.4 μs for on switching and 3.5 μs for off switching at 20 V. The number of switching cycles has reached 1 × 10⁷ cycles.