Most general-purpose circuit simulators, like SPICE and its derivates, are based on the nodal analysis [18]. For this purpose the simulator needs the terminal quantities of the device, i.e., currents and charges, and their derivatives, i.e., conductances and capacitances. Some simulators do not take into account charges and use currents only. In these cases, however, charge conservation is not guaranteed. 4.2 In general, inductances must be included as well. However, inductive effects are often negligible in CMOS VLSI circuits (except for RF circuits [37] and high-speed digital IO circuits). Furthermore, inductances can be modeled using a gyrator-C approach, which makes the simulator core simpler and guarantees automatic conservation of the magnetic energy [73].
The device model must provide these numbers fast and accurately. But how accurate is ``accurate enough'' and what are the tradeoffs between accuracy and speed? Furthermore, how can the data or parameters for the model be obtained efficiently?