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Free Analog Circuit Simulation

Temperature dependence in SPICE OPUS

Spice circuits have two global temperature parmeters: TEMP and TNOM. They can be altered

set temp=30
set tnom=27

They can also be swept in DC analysis by refering to them as @@@temp or @@@tnom. TEMP and TNOM are given in degrees Celsius. They are internally stored in Kelvins. TEMP is the circuit temperature and TNOM is the temperature at which the given model parameters are valid. If TEMP differs from TNOM, model parameters are internally recalculated to reflect the temperature dependence of the simulated devices.

  • Normal SPICE3 temperature dependence modeling:
    resistor, MOS1, MOS2, MOS3, MOS6, EKV MOS, diode, BJT, JFET, JFET2
    All of these devices have a TNOM model parameter that specifies the temperature at which the given model parameters are valid. They also have a TEMP instance parameter that tells the instance temperature for which the parameters are recalculated. In case instance TEMP equals model TNOM the parameter values provided on the .MODEL line remain unchanged (are not recalculated). In case TEMP is not given for an instance, the global circuit temperature(TEMP) is assumed for that instance. If the TNOM parameter is not given for a model, the global circuit TNOM value is assumed.
  • SPICE3 devices without temperature dependence modeling:
    MES, BSIM1
    These devices have no TEMP instance nor TNOM model parameters. BSIM1 has a TEMP model parameter, but it is not used in the simulation.
  • Non-standard SPICE3 temperature dependence modeling:
    BSIM2 has a TEMP model parameter. It defaults to global circuit temperature (TEMP) in case it is not specified. BSIM2 has no TEMP instance parameter nor TNOM model parameter.
    BSIM3v2, BSIM3v3, BSIM3SOI and BSIM4 have a TNOM model parameter. It defaults to global circuit nominal temperature (TNOM). These devices have no TEMP instance parameter.
  • Other SPICE3 passive devices:
    VSRC, ISRC, ...
    No temperature dependence modeling is provided for these devices.
  • Code models:
    The provided code models have no temperature dependence since they do not represent physical devices. They are used as abstract models for system-level modeling.
    However full support for accessing global temperature parameters is provided so it is possible to write code models for physical devices with temperature dependence.