Accurate electromagnetic simulation and measurement of millimeter-wave inductors in bulk CMOS technology

In radio frequency integrated circuits (RFICs) that use a low resistivity silicon substrate, spiral inductors show advantages in performance and size with respect to transmission lines, even at millimeter-waves (mm-waves). Design guidelines to create mm-wave inductors and equivalent circuit models describing them exist in literature. However, these models need to be parametrized either from test-structure measurement or electromagnetic (EM) simulations. This paper complements previous work by discussing problems that arise when trying to accurately determine the spiral's parameters as inductance and quality factor. Firstly, it provides guidelines for obtaining accurate and consistent results using different kinds of EM simulators. Secondly, the issue of accurately measuring the fabricated inductors by de-embedding test structure parasitics is discussed. The results obtained from measurements are compared to the simulation results of an inductor test structure, confirming the validity of the considerations before.