A Quasi-Two-Dimensional Model for High-Power RF LDMOS Transistors

Abstract

Abstract-A new quasi-two-dimensional (Q2D) model for laterally diffused MOS (LDMOS) RF power transistors is described in this paper. We model the intrinsic transistor as a series PHV-NHV network, where the regional boundary is treated as a revere biased p+/n diode. A single set of one-dimensional energy transport equations are solved across a two-dimensional cross-section in a "current-driven" form and specific device features are modeled without having to solve regional boundary node potentials using numerical iteration procedures within the model itself. This fast, process-oriented, nonlinear physical model is scalable over a wide range of device widths and accurately models DC and microwave characteristics. Index Terms-Field Effect transistor (FET), laterally diffused MOS (LDMOS), quasi-two-dimensional (Q2D), transistor model.

Process-orientated physics-based modeling of microwave power transistors: Small- and large-signal characterization

“…They are determined by numerically solving the physics-based equations which underpin the model [2] and are dependent on the device geometry and material properties, as determined by the fabrication process. The expression for the total gate charge is,…”

“…The Q2D model assumes that the electric field in the active channel is one-dimensional but retains a two-dimensional physical description of the active channel area. The electric field is determined selfconsistently with Poisson's equation and an energy balance equation [2].…”

“…A computationally efficient physicsbased model based on a quasi-two-dimensional (Q2D) description has been employed [2] with an emphasis here on developing and verifying a description of non-linear nodal charge behavior suitable for modeling large signal behavior for CAD implementation [3]. The algorithm is several orders of magnitude faster than most full two-dimensional device simulators and may itself be used directly as a non-linear model in microwave circuit simulation.…”