Model 2657A High Power System SourceMeter® Instrument Reference Manual
Section 4: Theory of operation
2657A-901-01 Rev. B/December 2012
4-9
The following figure shows a voltage sweep on a resistive load of 80 k
Ω
. For this example, the
System SourceMeter instrument is programmed to sweep voltage from 0 V to 1000 V, limit current
(6 mA) and limit power (5 W). When sweeping, the actual source output will vary according to the
programmed source value until the current limit is reached. As the figure shows, the output will source
the programmed value until placed in current compliance at the 6 mA limit. The sweep will then
continue (programmed V-source values will increase along the green sweep points line), but the
output will remain at the same voltage and current levels as when the instrument went into current
compliance. This continues until the programmed source value sweeps to a high enough level that
the power limit line is reached (5 W). At this point, the current and voltage will start to decrease,
lowering the current and voltage values along the DUT load line. When the last point is swept
(1000 V), the actual output would be 400 V (at 5 mA).
When the source goes into compliance, the operating point of the SMU will always remain on the load
line regardless of the programmed source value.
The Model 2657A can measure the function it is sourcing (source I measure I, or source V measure
V). This feature is valuable when operating with the source in compliance. When in compliance, the
programmed source value is not reached. Thus, measuring the source lets you measure the actual
output level. For more information, see
Source I measure I, source V measure V
).
Figure 74: V-source sweep operation in current and power compliance
NOTE
Quick Tip
Current
compliance
limit line
Power
compliance
limit line
I-meter
(I
M
)
5 mA
10 mA
1000 V
500 V
Programmed V-source
(V
S
)
Sweep
points line
80
k
Ω
DU
T
Load Line (R)
X
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