Characterization, design, modeling, and model validation of silicon-wafer M:N balun components under matched and unmatched conditions

In this paper, we characterize and model M:N baluns for silicon RFIC design. A modeling methodology is presented based on a geometrically scalable lumped-element approach that incorporates both skin effect and substrate loss. This approach is extended to include the effects of a patterned ground shield under the balun. The modeling approach is validated with measured S-parameters and extracted impedances from various circuit configurations. The impedance transfer characteristics of the model and balun over substrate and over a patterned ground shield are explored. Matching considerations are addressed by evaluating the model accuracy with measured data under matched and unmatched conditions.