13: LPT library function reference Model 4200A-SCS Parameter Analyzer
13-40 4200A-901-01 Rev. C / February 2017
The question mark (?) is the true or false determination.
As shown in the above figure, the true or false decision determines the voltage generated in the next
step of the binary progression.
Because the command initiates a current or voltage from a source, its placement in a test sequence
is critical. Therefore:
• Call the limitX and rangeX commands before the searchX command when all three refer to
the same instrument.
• Call the trigXg or trigXl command before the searchX command.
The search operation determines the source voltage or current required at one circuit node to
generate a trigger point value at a second node. The resolution of the result depends on the number
of iterations or steps and the actual current or voltage range used by the instrument.
For example, assume the minimum and maximum values of the source range are from 0 V to 20 V,
and the number of iterations is 16. The 20 V level automatically initiates a source-measure unit (SMU)
20 V source range. As a result, the resolution of the final source voltage returned is:
Note that changing the source mode of the SMU can modify the measure range. If the sourcing mode
is changed from voltage to current sourcing (or from current to voltage sourcing), the measure range
may be changed to minimize variations in the SMU output level. See rangeX (on page 13-83
) for
recommended command order.
Example
double ssbiasv, vgs1, vds1;
.
conpin(SMU1, 1, 0);
conpin(SMU2, 2, 0);
conpin(SMU3, 3, 0);
conpin(GND, 4, 0);
trigig(SMU2, +l.0E-6); /* Set trigger point for 1 uA. */
forcev(SMU3, ssbiasv); /* Apply a substrate bias */
/* voltage ssbiasv. */
forcev(SMU2, vds1); /* Apply a drain voltage of */
/* vds1. */
searchv(SMU1, 0.6, 1.7, 8, 1.0E-3, &vgs1); /* Set */
/* for 8 steps from 0.6 to */
/* 1.7 V at 1 ms.*/
/* per iteration; return the */
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