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The W8532EP IC-CAP Root Models Generator software license includes measurement and extraction procedures for the Keysight Root MOS, FET and Diode models.

The Keysight Root models are a data-based model, rather than a physical or empirical model. They generate a device-specific, large-signal model directly from measured DC and small-signal S-parameter data that accurately represents the terminal characteristics of the device. The model is constructed without circuit simulation or optimization. Use of S-parameter as well as DC data results in a model that can accurately predict nonlinear device performance with frequency dispersion, as a model simulated with a single set of nonlinear current functions cannot. The Keysight Root models predict the device performance as a function of bias, power level, and frequency. It allows circuits containing devices for which measured data exists, but for which there are no good physical or empirical models, to be simulated.

Each model generator toolkit manages the data acquisition: DC Bias levels and AC frequency range are first set by the user, the toolkit then controls the system hardware to take DC and S-parameter measurements. The model is thus generated without the usual need for simulation and optimization as required by all previous empirical models. Output data files are directly readable by the Keysight Advanced Design System (ADS). During a simulation, the tabular state-function data from the generated Keysight Root model is interpolated using multidimensional spline functions to emulate the terminal characteristics of the device.

This license includes three different toolkits for the following extractions:

  • Keysight Root FET Model - works for MESFETs and HEMTs (MODFETs). It is scalable to allow simulation of devices with different geometries based on the characterization of a single device. The present implementation is used for positive drain-source bias (Vds ≥ 0), which corresponds to the typical operating region.
  • Keysight Root MOSFET Model - can be applied to vertical, LD, and power MOS devices, where substrate effects do not need to be a part of the model. It can be used for both NMOS and PMOS devices.
  • Keysight Root Diode Model - used for varactor and Schottky diodes, in a two-port or one-port configuration