Model 2657A High Power System SourceMeter® Instrument Reference Manual
Section 4: Theory of operation
2657A-901-01 Rev. B/December 2012
4-15
The following figure shows a current sweep on a resistive load of 20 k
Ω.
For this example, the
System SourceMeter instrument is programmed to sweep current from 0 mA to 100 mA, limit voltage
(600 V), and limit power (50 W). When sweeping, the actual source output will vary according to the
programmed source value until the voltage limit is reached. As the figure shows, the output will
source the programmed value until placed in voltage compliance at the 600 V limit. The sweep will
continue (programmed I-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 voltage
compliance. This continues until the programmed source value sweeps to a high enough level that
the power limit line is reached (50 W). At this point, the voltage and the current will start to decrease,
lowering the current and voltage values along the DUT load line. When the last point is swept
(100 mA), the actual output would be 25 mA (at 500 V).
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 81: I-source sweep operation in voltage and power compliance
NOTE
Quick Tip
Voltage
compliance
limit line
Power
compliance
limit line
V-meter
(V
M
)
500 V
1000 V
100 mA
50 mA
Programmed I-source
(I
S
)
Sweep
points line
20
k
Ω
DU
T Load Line (R
)
X
Summary of Contents for 2657A
Page 3: ......