Varactor Characterization Procedure for Large-Signal High-Frequency Applications

The nonlinear modeling of varactors for microwave large-signal applications is carried out in this work. A model for a commercial varactor is obtained from multi-bias S-parameter and large signal single-tone measurements. The equivalent circuit for the extrinsic shell includes a topology that takes into account high-frequency phenomena. The intrinsic model is built by using a charge-controled equivalent circuit with two versions: one is quasi-static (QS) and the other is non-quasi-static (NQS). The extracted model has been included in a commercial CAD tool and validated under small and large signal conditions. It has been also used to extrapolate in frequency device behavior, showing the better performance of NQS approach versus the QS one.