Manuals >Netlist Translator for SPICE & Spectre >Chapter 8: Translating a Model
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MOSFET and JFET Models

The following information describes how various MOSFET models from Spectre are translated to the corresponding ADS models.

All Mosfet devices in Spectre reference a model by its instance name. Each Mosfet model in Spectre has a name value pair type=[npn|pnp], as well as a Level parameter.

The type value pair keyword is used to determine what device to place in the schematic, MOSFET_NMOS or MOSFET_PMOS. The Level is used to determine which model is placed and what value is set for Idsmod.

In the ADS netlist, the model is always called MOSFET, with the appropriate keywords NMOS and PMOS set to [0|1], and the parameter Idsmod set as specified in Table 8-9.

The only exception to this is the Mosfet device which refers to the Phillips MOS902 model. In this case, the device placed in the schematic will be MM9_NMOS or MM9_PMOS and the model will be MOS_Model9_Process. The netlist component is called MOS9. For both the MM9_NMOS and the MM9_PMOS, the translator sets the parameter Type=2 to indicate that it is a process-based model.

Table 8-9. Spectre Level Parameters Mapping (MOSFET)
Spectre Level
ADS Schematic Model
ADS
Netlist
Idsmod
ADS BSIM3 Version
0
 Not Translated



1
 LEVEL1_Model
 1

15
 Not Translated



2
 Not Translated



3
 Not Translated



30
 Not Translated



3002
 Not Translated



705
 Not Translated



902
 MOS_Model9_Process



903
 Not Translated



bsim3v3
 BSIM3_Model
 8
 3.22

Dependence Parameters

There are certain model parameters listed in the BSIM Models that reference additional parameters. These additional parameters are denoted in parenthesis using the letters L, W and/or P. As an example, the Dwg (L,W, P) parameter in the BSIM3 Model defines four separate parameters;

  1. Dwg: Coefficient of Weff's gate dependence.

  2. LDwg: Length dependence of Dwg.

  3. WDwg: Width dependence of Dwg.

  4. PDwg: Cross dependence of Dwg.

Each letter indicates a sensitivity parameter that exists in Spectre and ADS. These parameters are length(L), Width(W) and Cross(P). Refer to your Spectre and ADS component documentation for details.

The following MOSFET and JFET models are translated in ADS:

Binning Process

In order for ADS to translate the binning process, each binning definition is translated as a separate model.

Binning Example

The following is an example Spectre binning statement for a bsim model:

model ModelName ModelType {
   1: <model parameters> lmin=2 lmax=4 wmin=1 wmax=2
   2: <model parameters> lmin=1 lmax=2 wmin=2 wmax=4
   3: <model parameters> lmin=2 lmax=4 wmin=4 wmax=6
}

The Netlist Translator separates each binning reference into an ADS model. The example would result in three models with the names ModelName_1, ModelName_2, and ModelName_3. The models are then tied together by creating a "BinModel" and configuring the appropriate min/max values.

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