Compact Modeling and Electrothermal Measurements of Indirectly Heated Phase-Change RF Switches

Four-terminal, inline, indirectly heated phase-change switches (IPCS) have emerged as great contenders for reconfigurable radio frequency (RF) integrated circuits, providing state-of-the-art cutoff frequency thanks to their built-in dc-RF decoupling. However, the switching of IPCS devices is determined by their temperature which is challenging to predict. In this article, we present a physics-based compact model of the IPCS, validated by finite-element method simulations and measurements of IPCS devices. The model accurately predicts the thermal and electrical dynamics of the device by considering the changes in heater resistance, contact resistance, and parasitic capacitance. The complete model is implemented in Verilog-A, and a downloadable version is freely available at the nanoHUB.org. We show how the compact model can be used for rapid device evaluation and optimization between RF performance and energy efficiency. Nanosecond electrical thermometry of the heater for varying pulses during IPCS device operation and RF measurements is used to experimentally validate the model.