Zspice, a VerilogAMS based spicesolver for compact device modeling development

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Zspice, a Verilog-AMS based spice-solver for
compact device modeling development

• Laurent Lemaitre
• Motorola Geneva Switzerland

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Contents

• Goals of the presentation
• What is Verilog-AMS?
• What is a device model compiler?
• Performances of adms, a model compiler
• How works zspice, a spice-based mini-solver?
• Zspice in action
• Conclusions

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Goal of the presentation

• Try to convince you that
• the use of a model compiler and the use of
  Verilog-AMS, a high-level description language,
  can make compact device modeling a lot easier
• the use of zspice, a stand-alone spice-based
  mini-solver, can drastically help the fast
  prototyping of compact device implementation

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What is Verilog-AMS?

• Verilog-AMS is a Hardware Description Language
  used as a behavioral language for analog circuit
  simulators
• Verilog-AMS gives analog designers a means to
  encapsulate behavioral description of analog
  systems into modules
• Verilog-AMS can be re-used for compact device
  modeling.
• L. Lemaitre, ADMS Automatic Device Model
  Synthesizer, cicc2002
• M. Mierzwinski, Changing the Paradigm for
  Compact Model Integration in Circuit Simulators
  Using Verilog-A, nanotech2003
• K. Kundert, Automatic Model Compilation, An Idea
  Whose Time has Come www.designers-guide.com
• More info at http//www.accellera.org/

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Model Compiler I - overview
ADMS Automatic Device Model Synthesizer
Verilog-AMS Source Code
ADMS Parser
ADMS Data Base
XML
Internal
data
ADMS-XML Simulator-specific Interfaces
Other ADMS-XML Interfaces
Other
Code Generator
applications
C code Mica, Spectre, ADS,
Testing prior implementation
Documentation
Circuit Test benches
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Model Compiler II how to run it
SPECTREinterface.h BIPdefs.h BIPinitParameter.c BI
PloadJacobian.c BIPevaluateStatic.c BIPevaluateDyn
amic.c
BIPOLAR TRANSISTOR in VERILOG-AMS
Run admsSpectre
ready-to-compile C code
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Model Compiler III - interfaces

• CAD vendors can specify the way c code will be
  generated
• admsXml mymodule.va e ADSinterface.xml
• ready-to-compile c code for ADS
• admsXml mymodule.va e SPECTREinterface.xml
• ready-to-compile c code for Spectre
• admsXml mymodule.va e SPICE3interface.xml
• admsXml mymodule.va e StandAloneinterface.xml
• admsXml mymodule.va e TestBenchinterface.xml
• Note that core c code of a device model is the
  same between simulators. Integrity of the core of
  the model is preserved.
• if one bug is found in one model then a fix will
  apply to all models created so far.

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zspice I - overview

• verilog-ams devices
• voltage source
• simple resistor
• hbt device (device under test)

create c-code with adms
compile with c compiler

• xml-based specification
• zspice interface
• basic dc solver
• basic ac solver

shared inside community
executable

• different flavors of outputs can be created
• spice-like outputs (svg format)
• statistics (tables)
• re-use freeware, do not re-invent the wheel

zspice netlists
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zspice II - spice-like outputs
re-use of existing freewares SVGviewer inside
internet explorer
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zspice III - statistics
model under test VBIC with selft heating 1.1.5
and 1.2.0
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Work in progress

• Verilog-AMS subcommittee
• started April 2003
• mission extend verilog-AMS to cover compect
  device modeling
• adms and zspice proposed as test vehicule for the
  new language
• adms and zspice planned to be open-source
  (sourceforge)
• adms and zspice planned to be under the umbrella
  of this subcommittee
• Interested Parties
• Motorola - Mica
• Cadence - Spectre
• Agilent - ads
• Nassda - hsim
• Xpedion - GoldenGate
• Mentor - Eldo
• Helsinki University of Technology - Aplac
• University of Washington C. J. Richard Shi
  spice3 interface

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Conclusions

• adms, a model compiler based on Verilog-AMS, has
  been presented
• zspice, a stand-alone mini-solver zspice, has
  been presented
• Advantages/Results of the use of adms and zspice
  have been stressed