Agilent Future Device Modeling Trends 5991-1629EN c20121129 [15] free download

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IS FO SU C E US FE ED AT UR E Future Device Modeling Trends David E. Root G ood transistor models are essential for able to keep up. These and other challenges have spawned efficient computer-aided-design (CAD) much research into the advanced nonlinear device of nonlinear microwave and RF circuits, modeling techniques that are the focus of this article. monolithic microwave integrated cir- The scope of this article is restricted to modeling the cuits (MMICs), power amplifiers (PAs), nonlinear device for circuit and system simulation down- and nonlinear RF systems. Increasingly complicated stream. "Device" means not only transistor but also diode demands of the various semiconductor technologies (e.g., or other basic nonlinear component. For clarity and consis- GaAs pHEMTs, InP double heterojunction bipolar tran- tency with common usage, the term "compact model" will sistors (DHBTs), silicon on insulator (SOI), LDMOS, GaN be reserved for models defined by nonlinear equivalent HFETs, etc.), and their applications in terms of power and circuits in the time domain, or, equivalently, by a system of frequency of operation and complexity of applied signals nonlinear ordinary differential equations. Classically, com- (e.g., modern communication signals with high peak-to- pact model also meant constitutive relations [current-volt- average ratios) have placed commensurate requirements age (I-V) and charge-voltage (Q-V) relations for nonlinear on the accuracy and generality of the device models lumped elements] defined by explicit closed-form expres- used for design. New semiconductor material systems sions with parameter values specified by physics or extracted (e.g., GaN) have been developing at such a fast rate that