The SISSI software package

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The SISSI software package

• Electro-thermal simulation package integrated
  into an IC design framework, onto a top of a
  particular design kit.
• Fast and accurate electro-thermal simulation of
  analog IC-s by the method of simultaneous
  iteration.
• The electro-thermal netlist of the IC is
  automatically generated (based on its layout) for
  DC, AC and transient simulations.
• Three programs integrated into the Cadence Opus
  IC design framework
• electro-thermal simulation engine (TRANS-TRAN
  program),
• thermal simulator (THERMAN program),
• thermal modell generation tool (THERMODEL
  program).
• Complete user interface within the design
  framework.

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Simulation flow in SISSI

THERMAN
THERMODEL
TRANS-TRAN
THERMAN
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Electro-thermal model of an IC in SISSI

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• Example I CMOS OpAmp

A CMOS OpAmp was investigated. The same schematic
has been implemented in two layout versions. The
difference between the two layout versions was in
their thermal properties, which resulted in
different electrical caharactersitics due to
different thermal feed-back paths. Both layout
variants have been studied with SISSI and have
also been manufactured and measured. The
measurements proved the validity of the SISSI
simulations.
Steady-state temperature distri-bution of one of
the layout variants simulated by SISSI.
Steady-state sur-face temperature distribution
mea-sured on the same layout variant in the same
operating point as shown by the LCMAP thermal
mapping system..
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• CMOS OpAmp electro-thermal transient results

Transient waveforms on the output stage of a CMOS
OpAmp obtained for layout variants a) and b). The
over-shoot and the attenuation is due to
different the thermal feed-back paths realised by
the two different layout versions.
Output waveforms for both of the layout variants.
The simulated and measured curves show a good
agreement.
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Example II micro-thermostat
Heater transistors Sensor
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Micro-thermostat
Stabilsed region
Too little heating
Cooling required
Measured and simulated characteristics ambient
vs. chip temperature