Monolithic Integration of Phase-Change RF Switches in a Production SiGe BiCMOS Process with RF Circuit Demonstrations

We demonstrate for the first time the monolithic integration of phase-change RF switches into the backend of a production SiGe BiCMOS process. We show that the monolithic integration of PCM RF switches did not impact the performance of the BiCMOS process components, such as FETs and bipolar devices, by comparing end-of-line data for wafers fabricated with and without PCM RF switches. Using the backend RF components in the Tower Semiconductor SBC18H3B process, three different RF circuits were realized. A five bit DSC with 32 states is shown with a tuning range from 33 fF to 6.75 pF in ~215 fF increments. A wideband 24.25 GHz to 33.4 GHz switched filter using two SPDTs is also demonstrated. And finally, a tunable bandpass filter that uses seven phase change switches is shown to have tuning between 400 MHz up to 6 GHz.