Equivalent Circuit; Connection Considerations - Keithley 2500 User Manual

2-6 Connections

Equivalent circuit

Figure 2-4
The circuit includes two ammeters to make current measurements and two voltage sources
to bias the DUTs. Note that channel 1 and channel 2 analog common terminals are floating
and independent of one another.
Figure 2-4
Equivalent circuit of photodiode test connections
Back
Photodiode
Laser
Diode
Forward
Photodiode

Connection considerations

To avoid noise and offset currents that could degrade measurement accuracy, be sure to
use only quality, low-noise triax cables for INPUT connections. Also keep cables and test
fixtures away from vibration and varying temperatures to minimize generated cable cur-
rents. See
possible measurement problems and how to avoid them.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com
shows an equivalent circuit for the connection scheme shown in
I
INPUT HI
OUTPUT
OUTPUT
INPUT HI
I
Appendix F, "Measurement Considerations,"
Model 2500 and 2502 User's Manual
Figure
Channel 1
A
Channel 1
Analog
Common
V-Source
Channel 2
V-Source
Channel 2
Analog
A
Common
Model 2500
for information on these and other
2-3.