A Four-Terminal, Inline, Chalcogenide Phase-Change RF Switch Using an Independent Resistive Heater for Thermal Actuation

An inline chalcogenide phase-change radio-frequency (RF) switch using germanium telluride and driven by an integrated, electrically isolated thin-film heater for thermal actuation has been fabricated. A voltage pulse applied to the heater terminals was used to transition the phase-change material between the crystalline and amorphous states. An ON-state resistance of 4.5 Ω (0.08 Ω-mm) with an OFF-state capacitance and resistance of 35 fF and 0.5 MΩ, respectively, were measured resulting in an RF switch cutoff frequency (F_co) of 1.0 THz and an OFF/ON resistance ratio of 10⁵. The output third-order intercept point measured , with zero power consumption during steady-state operation, making it a nonvolatile RF switch. To the best of our knowledge, this is the first reported implementation of an RF phase change switch in a four-terminal, inline configuration.