Tektronix Keithley SourceMeter 2470, Справочное руководство

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2470 High Voltage SourceMeter Instrument Reference Manual Section 5: Source-measure considerations
2470-901-01 Rev. A /
May
2019 5-21
A more comprehensive method of testing components to specify the DUT breakdown voltage is to
measure the actual component breakdown voltage. To do this on a 1000 V rated MOSFET, you need
to switch the sourcing method to current and the limit voltage to 1100 V (higher than the highest
expected breakdown voltage). Sourcing the value of the breakdown current permits the SMU to
measure the actual breakdown voltage of the component, which occurs precisely when the SMU
reaches the programmed source current. When this operating point is reached, a voltage
measurement records the actual breakdown voltage of the component, after which the small source
current used to find this breakdown voltage can be reduced to zero while waiting for the next
component to test. The entire test should be done quickly with the lowest possible breakdown current
to limit device self-heating. When performing this test, if the breakdown protection is off, you may find
that at the exact moment of component breakdown, the current may exceed the limit current
value. With the breakdown function on, the peak current is limited to V
OUTPUT
/500.
The options for breakdown protection are only available using remote commands. To set it using a
SCPI command, refer to :SYSTem:BREakdown:PROTection (on page 12-104). To set it using a TSP
command, refer to smu.breakdownprotection (on page 14-107).
Calculating accuracy
Instrument accuracy specifications can be expressed in a variety of ways. To illustrate how to
calculate measurement errors from instrument specifications, the following topics provide examples of
calculations.
Calculating source or measure accuracy
The source and measure accuracy specifications are expressed as a percent of reading or source
value and an offset. To calculate source accuracy, use the formula:
Accuracy =
±
(
%
of reading + offset)
For example, assuming:
•
Current output = 100 mA on 100 mA range
•
Accuracy specification = ± (0.025% of 15 µA)
Calculate the current source accuracy as shown in the following equations.
Error = {(100 mA * 0.00025) + 15 µA}
= ± {25 µA + 15 µA}
= ± 40 µA
Thus, the current output in this example could fall anywhere within the range of 100 mA ± 40 µA, an
uncertainty of ± 0.04%.