Keithley 4200A-SCS Reference Manual page 934

Model 4200A-SCS Parameter Analyzer Reference Manual
When multiple calls to the sweepX command are executed in the same test sequence, the smeasX,
sintgX, or savgX arrays are loaded sequentially. This appends the measurements from the second
sweepX call to the previous results. If the arrays are not dimensioned correctly, access violations
occur. The measurement table remains intact until the clrscn, execut, or devint command is
executed.
Defining new test sequences using the smeasX, sintgX, or savgX commands adds commands to
the active measure list. The previous measures are still defined and used. The clrscn command is
used to eliminate the previous measures for the second sweep. Using the smeasX, sintgX, or
savgX command after a clrscn command causes the appropriate new measures to be defined and
used.
When the first sweep point is nonzero, it may be necessary to precharge the circuit so that the
sweepX command will return a stable value for the first measured point without penalizing remaining
points in the sweep. For example:
double ires[6];
conpin(SMU1, 10, 0);
conpin(2, GND 0);
forcev(SMU1, 5.0); /* Force 5 V to charge. */
delay(10); /* Wait for precharge. */
smeasi(SMU1, ires); /* Set up measurement. */
sweepv(SMU1, 5.0, 10.0, 5, 2.5E-3); /* Make the real measurement. */
Note that changing the source mode of the source-measure unit (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 resi[11], ssbiasv;
double vds[11];
.
conpin(SMU1, 1, 0);
conpin(SMU2, 2, 0);
conpin(SMU3, 3, 0);
conpin(GND, 4, 0);
forcev(SMU3, ssbiasv); /* Apply substrate bias */
/* voltage SSBIASV. */
forcev(SMU1, -0.1); /* Apply a gate-to-source */
/* voltage of -0.1V. */
rtfary(vds); /* Return force array*/
smeasi(SMU2, resi); /* Perform a series of current */
/* measurements; return */
/* the results to the array */
/* resi. */
sweepv(SMU2, 0.0, 5.0, 10, 2.5E-3); /* Generate */
/* 11 steps and 11 */
/* points each 2.5 ms duration, */
/* ranging from 0 to 5 V. */
4200A-901-01 Rev. C / February 2017
Section 13: LPT library function reference
13-89