Keithley 6220 User Manual

Model 6220/6221 Reference Manual Output Connections 2-13
Return to Section 2 topics
Cable Guard (which has less noise than banana jack Guard) can also be used to
measure voltage as previously described. For best accuracy, it is recommended
that banana jack Guard be used.
Figure 2-9
Using banana jack Guard to measure voltage
Floating the current source
Using an external source in the test system may require that the Model 622x
current source float off Earth Ground. An example of such a test system is shown
in Figure 2-10, which includes an external voltage source. Notice that Output Low
of the voltage source is connected to earth ground.
NOTE For the Keithley Model 2182/2182A Nanovoltmeter, the
input impedance for the 100V range is 10MΩ. Therefore,
for higher impedance DUT, voltage should be measured
at banana jack Guard or Cable Guard.
10MW
DUT
10µA
I-source
High
Low
622x
10MW
R
IN
V
5µA
5µA
Low-Impedance Voltmeter
+50V
x1
10MW
DUT
10µA
I-source
High
Low
622x
10MW
Rin
V
10µA
Low-Impedance Voltmeter
+100V ±1mV
Banana
Jack Guard
A) 50% measure error due to voltmeter loading
B) Using banana jack Guard to measure voltage
V
DUT = I x R
= 5µA x 10MW
= 50V
V
DUT = I x R
= 10µA x 10MW
= 100V
V
GUARD = VDUT ±1mV
= 100V ±1mV
V
GUARD
Loading Error =
V
RIN = I x R
= 5µA x 10MW
= 50V
V
RIN
VRIN + VDUT
= 50%
= 50V / 100V
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Keithley 6220 Specifications

General

Brand	Keithley
Model	6220
Category	Measuring Instruments
Language	English