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A novel hybrid approach integrating a MEMS switch with a gas discharge tube plasma cell to enhance switch survivability and isolation, especially at high incident power levels, is demonstrated. The theory of operation is discussed including consideration of the underlying plasma phenomena as well as the practical integration details. Measurement of a fabricated prototype is presented. Discussion of measurement challenges and potential solutions is accompanied by detailed explanations of measurement practice. Measurements provide insights into applied RF plasmas not present in the body of literature. Wideband enhancement of isolation by more than 10 dB at 50 W incident power is observed in a quasi-absorptive mode with increasing isolation over power. No penalty to the excellent linearity of MEMS switches is detected with a measured IIP3 of 75.3 dBm. Advantages in linearity as compared to semiconductor-based power limiting solutions are shown and demonstrate state-of-the-art performance. An incremental insertion loss of less than 0.2 dB with a return loss better than 12.5 dB is reported. Measurement of the effects on MEMS switch timing parameters as well as time domain characterization of the plasma breakdown is included.

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This paper presents a low-loss optically-controlled inline RF switch suitable for L-and S-band applications. Under 1.5 W laser power, the switch exhibits a measured ON-state insertion loss of less than 0.33 dB and return loss better than 20 dB across the band. The measured OFF-state isolation ranges from 27 dB at 1 GHz to 17 dB at 4 GHz. The switch comprises a single silicon chiplet excited by a 915-nm laser fiber which creates electron-hole pairs, thereby exciting the ON-state silicon plasma. An optical fiber is guided through the bottom of the RF substrate to illuminate the chiplet, which bridges a 1.075-mm microstrip line gap. To the best of our knowledge, this is the lowest-loss silicon plasma switch demonstrated today.