Overview

Intusoft has introduced support tools for a new non-proprietary HDL (Hardware Description Language). The support comes in two forms. A new Code Model Software Development Kit, or CMSDK, has been introduced to allow designers to develop and debug HDL models for use with IsSpice4 . Secondly, the companies' SPICE 3 simulator, IsSpice4 , now includes simulator enhancements and support for models written using the HDL.

The HDL modeling architecture is based on the publicly available Unix based XSPICE program, distributed by the Georgia Tech Research Corporation, a unit of the Georgia Institute of Technology. The HDL is called XDL (eXtended Description Language) and it differs from current AHDL offerings which are proprietary in nature and only work with Unix based simulators. XDL is based on the C programming language and is the only non-proprietary analog and mixed signal HDL available for Windows. It represents a new and powerful approach to making simulation models and interfaces.

The Intusoft CMSDK provides a major breakthrough in HDL technology in terms of power and affordability. It allows the designer to add new analog, digital, or mixed analog/digital models to IsSpice4 very easily. Adding a model to SPICE in the traditional manner can take several months. The Intusoft CMSDK cuts this time to days or even hours. XDL modeling is also called "Code Modeling" because models are developed using C subroutines. The use of a standard programming language like C greatly lessens the learning curve since users do not have to learn a proprietary language or use unfamiliar tools. When coupled with IsSpice4 's behavioral modeling features, the XDL modeling capability completes the AHDL picture for IsSpice4 giving it all the features and portability of even the most powerful modeling languages at a cost far below any existing solution.


What Can You Do With XDL?
XDL models open many areas of simulation to SPICE users that were formally closed because of the complexities of modeling or the inefficiency of behavioral models. Designers can now efficiently simulate system and board level designs containing mixed mode circuits, sample data systems, and mixed domain (electrical-physical) descriptions, using a top-down simulation methodology. XDL models may be as simple as a gain block or as complex as a new MOSFET model. They can perform virtually any function, analog or digital, with any level of accuracy. XDL also accepts a user defined data type allowing non-electrical systems and processes to be simulated.

Unfortunately, currently available AHDL products are targeted mainly at device modeling. This is not the case with XDL and to think of XDL as only a device modeling language would severely limits its potential. XDL provides hooks into the SPICE simulation engine. And since models are written in C the user has access to the operating system. This allows XDL to interface SPICE to other simulators, other software utilities, or even directly to hardware. XDL is simply not restricted to device modeling like other AHDLs.

Once created, XDL models behave exactly like traditional SPICE models. They become an extension of the standard devices offered in IsSpice4 and are accessed in the same manner as a diode or BJT. The XDL (C source) can be used with any simulator that understands the XSPICE extensions. The CM-SDK also offers special provisions for converting existing SPICE models to XDL code. Table 1 describes some of the major benefits of using XDL, the Intusoft CM-SDK, and IsSpice4.

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