Keithley 6220 DC, Руководство пользователя

Страница: 115 / 171

5-38 Delta, Pulse Delta, and Differential Conductance Model 6220/6221 User’s Manual
Return to Section 5 topics
Measurement units
The fundamental measurement for Differential Conductance is differential voltage
(dV). However, the dV reading can be converted into a differential conductance
(dG), differential resistance (dR), or power (Watts) reading. See
page 5-11 for
details on selecting “ Measurement units ”.
With Ohms (dR) or Siemens (dG) measurement units selected, the reading is cal-
culated as follows:
dR = dV/dI
dG = dI/dV
Power – With Power measurement units selected, power is calculated using
Average Voltage and Average Current. Details on Differential Conductance Power
calculations are provided in Section 5 of the Reference Manual (see “Average
Voltage and Power”).
Configuration settings
Differential Conductance settings from the front panel are described as follows.
These parameters are set from the DIFF CONDUCTANCE menu, which is
accessed by pressing the
CONFIG key and then the COND key.
The equivalent remote programming commands to configure Differential Conduc-
tance are summarized in
Table 5-4 .
Step – The step size specifies the size increment for each step of the sweep. In
Figure 5-10 , the 10µA steps are shown by the dashed line. If the step size is set to
be larger than the start-stop interval, the step size will be readjusted to provide a
100-point Differential Conductance sweep.
Step is a magnitude and is therefore always set as a positive value. Step can be
set from 0 to 105mA. The default step size is 1µA.
Start – The start level for the sweep applies to the middle step of the first cycle. As
shown in Figure 5-10 , the 0µA Start level is actually the second step of the sweep.
The start level can be set from -105mA to +105mA. The default start level is -
10µA.
Stop – The stop level for the sweep applies to the middle step of the last cycle. As
shown in Figure 5-10 , the 50µA Stop level is actually the second last step of the
sweep. The stop level can be set from -105mA to +105mA. The default start level
is +10µA.
Delta – The specified Delta is the differential current (dI) for the sweep. It is alter-
nately added to and subtracted from each subsequent step in the sweep. As
shown in
Figure 5-10 , 10µA is added to the odd numbered steps and then sub-
tracted from the even numbered steps. Model 2182/2182A A/D readings are per-
formed at each stepped delta level. Delta is a magnitude and is therefore always
set as a positive value. Delta can be set from 0 to 105mA. The default Delta set-
ting is 1µA.