eldo_user

Optimization
Specifying Design Objectives Using .EXTRACT
Examples
Examples of forbidden situations.
Example 1
The situation in the following example is detected and forbidden. Here the analysis command
should be driven by the values of VDS and VGS specified in the .DATA construct. The use of
.DATA constructs is then restricted.
DC Operating Point analysis is performed for every value of VDS from 0 to 40 with a step
increment of 1, and every value of VGS between 4 and 16 with a step increment of 2.
.DC VDS 0 40 1 VGS 4 16 2
Three design objectives are defined for the variable IDS through the .DATA statement labeled
MOSFIT, corresponding to the values of VGS equal to 4 and the values of VDS equal to 1, 2,
and 3 respectively. The current through voltage source VDRAIN is optimized to fit the values
of IDS. The values of VDS and VGS for the measurements correspond to the simulation points
on a short range as specified in the .DC command.
.EXTRACT DC LABEL=FIT_IDS
+ FITTING
+ MOSFIT(IDS) I(VDRAIN)
.DATA MOSFIT
+ VDS VGS IDS
+ 1.000E+00 4.000E+00 1.574E+00
+ 2.000E+00 4.000E+00 1.806E+00
+ 3.000E+00 4.000E+00 1.826E+00
.ENDDATA
Example 2
Consider the next example where interpolation is required to obtain the values for the measures
required for optimization.
Interpolation for measures is forbidden with optimization, since this technique introduces
additional errors that cannot be bounded, and provides non-smooth measurements. When
optimization is required, all simulation points must be included in the set of simulation points.
A small signal analysis is performed for frequencies in the range [100 kHz, 1 GHz] with 2
points per decade. The voltage magnitude at node 16 VM(16) is optimized to fit the values of
the data labelled V16 in the statement .DATA VFIT.
Eldo® User's Manual, 15.3 607