An accurate parameter extraction method for RF LDMOSFET small-signal model

A new direct parameter extraction method of small-signal equivalent circuit for radio frequency laterally-diffused Metal Oxide Semiconductor Field Effect Transistor (RF LDMOSFET) with Faraday shield biased in cut-off operation is presented in this paper. A series of analytical equations are derived for non-linear rational function fitting as well as linear regression to measured device frequency response characteristics. The method is successfully applied to a set of fabricated RF LDMOSFETs with different geometry scales. As a result, all of the cut-off small-signal equivalent circuit elements are determined. Validation of the extraction method is verified by good agreement between the simulation results and the corresponding measurement data. In addition, reasonable physical meaningfulness of the method is further demonstrated by characterizing the device geometrical dependences of the extracted gate-drain capacitance (C_gd) and drain-source capacitance (C_ds).