Tektronix KEITHLEY SourceMeter 2606B Reference Manual page 231

Section 8: Theory of operation
The delay factor is used to multiply the default delays. Setting this value above 1.0 increases the
delays; a value below 1.0 decreases the delay. Setting this value to 0.0 essentially turns off
measurement delays. This attribute is only used when smuX.measure.delay is set to
smuX.DELAY_AUTO.
Effects of load on current source settling time
The settling time of the source-measure unit (SMU) can be influenced by the impedance of the
device-under-test (DUT) in several ways. One influence is caused by an interaction between the
impedances of the SMU current source feedback element and the DUT. This interaction can cause a
reduction in the bandwidth of the SMU. This reduction results in an increase in the settling time of the
current source.
There is a maximum DUT impedance for each current source range for which the specified current
settling times are maintained. The following table lists the DUT impedances for each of these current
source ranges. For the latest specifications, go to tek.com/keithley. The settling time on a current
source range can increase significantly when measuring DUTs that have an impedance that is higher
than the maximum DUT impedance listed below.
Maximum DUT impedances for specified settling time
performance
Range
100 nA
1 µA
10 µA
100 µA
1 mA
10 mA
100 mA
1 A
3 A
8-16
SMU feedback Maximum DUT
impedance impedance
40 MΩ 20 MΩ
1.2 MΩ 600 kΩ
400 kΩ 200 kΩ
12 kΩ 6 kΩ
4 kΩ 2 kΩ
120 Ω 60 Ω
40 Ω 20 Ω
1 Ω 6 Ω
0.3 Ω 1.5 Ω
Model 2606B System SourceMeter® Instrument Reference Manual
2606B-901-01 Rev. C November 2021