Wide Bandwidth, High Power Radio Frequency Limiter Based on Lanthanum Cobalt Oxide on SiC

The insulator-to-metal phase transition oxides offer an opportunity to overcome the current constraints in RF limiter technology. In this article, we present shunt power limiters based on sputtered lanthanum cobalt oxide (LaCoO3, LCO) on silicon carbide substrate. The LCO limiters presented in this article achieve limiting behavior over the broadest temperature range ever reported for an insulator to metal transition (IMT) material-based RF switch, from 10 °C to 225 °C. At 2 GHz, the power limiter provides <1-dB insertion loss up to 75 °C, resilience up to 40 dBm, and leakage power of 20 dBm. S-parameter testing was conducted from 0.1 to 50 GHz, verifying the broadband viability of LCO microwave devices. We present low small signal losses at high temperature and frequency, with a maximum insertion loss of 1.15 dB at 125 °C and 50 GHz. Finally, we report on a 3-D multiphysics model that accurately predicts the LCO RF device behavior and can be used for further device optimization.