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Simulators in the Affirma Analog Design Environment
Sachin Shinde
Xiaolai He
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• Cadence design framework II environment
consists of many Cadence tools which are
interoperale without re!uiring data conversion"• D#II is an open system allowing the user to
integrate third party tools like simulators using
programmale netlister or enter their own design
data"
Simulators
Direct Simulators
Eg" Spectre
Socket Simulators
Eg" SpectreS$ cdsSpice
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Direct Simulation %s Socket
Simulation• Direct Simulation
& 'his is a preferred method ecause uses the new features addedto Spectre simulator and uses direct simulation"
& (ith direct simulation$ the netlist uses the synta) of the simulator
w*o any processing to evaluate e)pressions" & 'he netlist is a direct reflection of the design"
• Socket Simulation & 'he netlist is processed y Cadence S+ICE to evaluate all
e)pressions and resolve passed parameters"
& Socket methodology is used to integrate a simulator if the currentsimulator cannot handle e)pressions or parameters passing"
& Efficient operation in various interactive mode such as simulationstop and restart or change values and resimulate"
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,ore Aout Direct Simulation
• Important -enefits of Direct Simulation
& Improved performance in netlisting"
& Improved performance of simulation for
Spectre"
& .eadale netlists"
& .ead only design can e simulated provided
that they are e)tracted" & Improved support of standalone netlisting"
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/ther Simulators
• In addition to Cadence S+ICE and Spectrecircuit simulator popular analog andmicrowave simulators can e used through
a set of integrated simulation interfaces" & Eg" ,eta Software0s HS+ICE circuit simulator$
H+0s ,1S microwave simulator$ CompactSoftware0s Harmonica microwave simulator"
• (e have A##I.,A HS+ICE interfaceinstalled on our system"
• (e do not have a HS+ICE simulator
installed yet"
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Spice$ +Spice and HSpice
• S+ICE was originally developed at theElectronics .esearch 2aoratory of the3niversity of California$ -erkeley 456789
• +Spice is a +C version of S+ICE4,icroSim Corp"9
• HSpice is a version 4Avant:"9 that runs on
31IX workstations and larger computers"'his is particularly fast version and onethat should e normally used"
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Spectre Simulator
• A##I.,A Spectre simulates analog and digitalcircuits at the differential e!uation level"
• 'he capailities of Spectre circuit simulator aresimilar in function and application to S+ICE$ utSpectre is not descended from S+ICE"
• Spectre and S+ICE use the same asicalgorithms eg" 1ewton .aphson$ direct matri)solution$ ut every algorithm is newly
implemented"• ,anual claims Spectre algorithms are the est
currently availale and is faster$ accurate$ morereliale and more fle)ile than previous S+ICE
like simulators"
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Improvements of Spectre over
S+ICE• Improved Capacity
• Can simulate larger circuit"
• Improved Accuracy• Improved component models and core simulator algorithms
• Improved Speed
• Improved .eliaility• Improved ,odels• Analog HD2S
• (orks with Spectre HD2 and %erilog; A
• .# Capailities• Analyses of ,i)er$ oscillators$ sample hold and switched;capacitor filter
• ,i)ed Signal Simulation• Spectre circuit simulator coupled with the %erilog;X2 simulator in the A##I.,A
environment can simulate mi)ed analog and digital circuit
• Environment• #ully integrated into Cadence D#II for A##I.,A and also in Cadence Analog
workench design system
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S+ICE compatiility of Spectre
• S+ICE is a industry standard language withmany variations of S+ICE synta) on markettoday"
• Each vendor modifies it with different capailitiesand*or slightly different synta)"
• #or convince of S+ICE users A##I.,A Spectresimulator provides S+ICE .eader as an
e)tension to its native language that acceptsmost variations of S+ICE input"
• S+ICE .eader supports S+ICE
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Cadence S+ICE
• Cadence S+ICE simulator is an interactivecircuit simulator ased on 3C -erkley0sS+ICE< program"
• ,odified architecture for interactiveoperations plus enhancement thatautomatically improve convergence with
prolem circuit"• Can e used within the Analog simulation
environment or as a standalone simulator"
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Cadence D#II Architecture
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HS+ICE Simulator
• >old standard for accurate circuit simulation"• E)tensive set of uild in devices$ models including models for small
geometry ,/S#E' and ,ES#E'"• Compatile with Spice and ,SI1> input format"• Cadence supports a lirary of primitives and a full interface of
HSpice"• High +erformance?
• HS+ICE achieves upto
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Inverter E)ample
• Compared performance of Spectre$
SpectreS$ cdsSpice and HS+ICE
simulators using the inverter e)ample"
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A,I@1 ,odels in Spectre and
HspiceSpectre 4A,I@19 Hspice 4A,I@19
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Simulation with SpectreS
• 3sed the spectre,/S models forsimulation in thenominal mode"
• Does not simulateusing the hspicemodels"
• 'otal time re!uired forthe
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Simulation with cdsSpice
• Can e simulated
using either the
Hspice or Spectre
models for simulationin the nominal mode"
• 'otal time re!uired
for the
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Simulation with HS+ICE
• 3sing the A##I.,A
hspice interface could
generate the netlist
fro HS+ICE"• Couldn not simulate it
cause do not HS+ICE
simulator is not
installed"
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1CS30s Spectre and Hspice
Comparison• 'he process? 'S,C @"
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Conclusion
• ,any variations of S+ICE simulators are availale in themarket each optimied for different function"
• 'he choice of a type of S+ICE simulator is very prolemdependent"
• Spectre availale in A##I.,A is not a S+ICE simulator"• Spectre is well documented"
• Cadence S+ICE is the S+ICE simulator availale in A##I.,A which can e used with cdsS+ICE or
SpectreS interface"• In the inverter simulation we found spectre simulator to
e much faster than SpectreS and cdsSpice"
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Conclusion 4cont"9
• CouldnFt compare the speed of simulation forSpectra and Hspice simulators"
• 1CS3 tutorial states that they didn0t find andsignificant difference etween HS+ICE andSpectre simulations results"
• In general we would recommend the use ofSpectra over SpectreS and cdsSpice if thedevelopment environment is Cadence"
• If portaility of design across differentenvironment is desired a Spice ased simulatorlike Hspice or cdsSpice is recommended"
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.eferences
• Affirma Analog Circuit Design Environment
3ser >uide$ Cadence$ +roduct version
""$ April