A Low-Loss Directly Heated Two-Port RF Phase Change Switch

In this letter, we report on the design, fabrication, and measured results of a directly heated phase change RF switch (or via) using germanium telluride in a four-terminal configuration. The switch is heated using a separate heater path combining the advantages of directly heated vias, such as low power dissipation for phase transition, and indirectly heated vias, such as high power handling capability. The phase change switch shows an insertion loss of less than 0.6 dB and an isolation of higher than 20 dB at frequencies up to 20 GHz, indicating a cutoff frequency of more than 3.7 THz. The switch area is only 4 mu m x 6 mu m, which is smaller than RF MEMS switches with similar insertion loss performance. To the best of our knowledge, this is the first report on a four-terminal, directly heated, RF phase change switch.