4.5 Interface to a Large-Signal Model

With a more complete and accurate simulation of small-signal S-parameters as a function of bias, large-signal quantities are available. A second tool developed allows for the conversion of simulated S-parameters and the underlying DC-current files .esb into data formats, which can be used by large-signal extraction tools, such as ICCAP [6]. PALACE (Physical Analysis Using Large-Signal Characteristics Extraction) is an interface developed to extract the large-signal parameters from simulated S-parameters and the available DC currents. The completeness of the device simulations including breakdown and thermal information is sufficient to allow for this approach of extracting large signal quantities.

Figure 4.6: Program sketch of PALACE.

The increase of available computational resources in combination with an computationally efficient AC analysis allow for extraction within reasonable calculation time using full two-dimensional simulation [187]. Fig. 4.6 shows a program sketch of PALACE. The program includes a conversion routine that converts small-signal equivalent circuit .esb files extracted from the small-signal program PARAS to touchstone .s2p files, or a .citi file. Since the extraction of the parasitic elements includes a major part of the large-signal measurements and the inclusion of frequency dispersive effects is especially important and provides significant information whether the compact large-signal model will finally converge, device simulation focuses on the intrinsic transistor as given by the simulation shell in Fig. 4.1. The parasitics are thus determined from measurements from the particular technology. The latter is especially true for multi-gate finger high-power HEMTs.