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Optimization of Sweep Simulations
Optimization
Optimization of Sweep Simulations
The following topics explain how the optimizer behaves during a sweep analysis, and the
options available to influence that behavior. They introduce the notion of sweep parameters and
their role in the optimization process.
The circuit parameters that are to be adjusted (such as width and length for MOS) should be
considered separately from those associated with DC multi-point, transient, small-signal,
frequency, or parametric analysis. The former are known as design variables and the latter
design parameters.
During a sweep analysis, the design parameters are a real-valued set Ω of user-defined
discretizations. These are known as sweep parameters and are denoted by the Greek letter ω.
Sweep parameters ω vary only within the simulator. They are not affected by the optimization
algorithm. The parameter set Ω can be discretized using .TEMP, .DATA, and .STEP
commands. For example, the Voltage-Temperature parameters temperature-voltage (TEMP,
PVDD):
.STEP TEMP -25 150 5
.STEP PARAM PVDD 2.7 3.3 0.1
define a cartesian product or a box Ω = [-25, 150] × [2.7, 3.3] in the 2-dimensional space R 2 .
An example of a 2-dimensional domain Ω is shown in Figure 13-8. It is obtained from the
multi-step specification:
* Sweep parameters
.STEP PARAM OMEGA_1 omega1_start omega1_end omega1_step
.STEP PARAM OMEGA_2 omega2_start omega2_end omega2_step
Figure 13-8. Discretization of Design Parameters
Eldo® User's Manual, 15.3 633