Test Structures and Techniques for On-Wafer CMOS TRL Calibration

In this paper, we demonstrate for the first time a TRL calibration kit fabricated in CMOS technology. To fulfill a basic requirement of high probe-isolation of the TRL method, we have based all fabricated calibration standards on a shield-based measuring fixture that heavily reduces the effects of the semiconducting substrate. We analyze the electrical performance of the standards, including their accuracy, and the performance of CMOS-based TRL calibration is compared to a reference calibration based on the LRRM technique and a high-precision impedance standard substrate. We find that CMOS TRL calibration is indeed feasible for measurements in the low-gigahertz frequency range but not without implementation problems.