eldo_user

Setting Up An Analysis
Other Miscellaneous Analyses
Other Miscellaneous Analyses
Other miscellaneous analyses are:
Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Aging and Reliability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Check Safe Operating Area Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
High Impedance Node Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Power Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Viewing Power Analysis Results Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
Optimization
The Eldo optimizer is a general-purpose electrical circuit optimization program. The term Eldo
optimizer refers to the complete set of optimization tools available through the .OPTIMIZE
command. The optimizer will calculate the value of parameters (the optimization variables) in
the circuit such that the behavior or the characteristics of the circuit conform as close as possible
to the specifications. The optimizer can achieve a simultaneous improvement in AC, DC,
Transient domain, Steady-State and Modulated Steady-State analyses.
The designer specifies the design objectives and the optimizer will adjust the component
parameters of the circuit (such as resistor or capacitor values, the b value of a transistor, widths
and lengths of a MOSFET) to meet a specified electrical performance. Optimization can be
applied to:
• Circuit parameters.
• Model parameters.
• Element parameters.
• Device lengths, widths, areas, and peripheries.
The parameter values must conform to the manufacturing limits, process limits, or discrete
device values. To achieve this, restrictions can be specified on the design parameters. Various
constraints (or inter-relations) can be specified, for example, circuit parameters must be
non-negative, or must not violate upper boundaries. In addition, more complicated constraints
can be specified, for example, how components physically interact with each other to produce
non-linear relations.
The process of identifying the objective, variables, and constraints for a specific problem is
known as modeling. The construction of an appropriate model is the first step (sometimes the
most important) in the optimization process. If the model is too simplistic, it will not generate
useful insights into the practical problems. If too complex, it may become difficult to solve.
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Eldo® User's Manual, 15.3