5-34
Delta, Pulse Delta, and Differential Conductance
Model 6220/6221 User’s Manual
Return to
3.
When using a Fixed output, use the SOUR:PDEL:INT command to set the
Pulse Delta cycle time period (in PLCs).
When using Sweep output, use the SOUR:DEL command to set the Pulse
Delta cycle time period (in seconds) for a linear or log sweep. For a custom
sweep, use the SOUR:LIST:DEL command to cycle time (in seconds). See
for details on sweeps.
4.
When using a Fixed output, use the SOUR:PDEL:RANG command to set the
source range. When using a Sweep output, use the SOUR:SWE:RANG com-
mand to set range.
5.
After setting up Pulse Delta using the setup commands, the :ARM command
arms Pulse Delta. During the arming process, the Model 622x communicates
with the Model 2182A.
When armed, Pulse Delta will start when the Model 6221 is triggered. Pulse
Delta can be “un-armed” by sending the following command:
SOURce:SWEep:ABORt.
The query form for the arm command (SOUR:PDEL:ARM?) is used to deter-
mine if Pulse Delta is armed. A returned “1” indicates that Pulse Delta is
armed. A “0” indicates that Pulse Delta is not armed.
If the Model 6221 is already armed for another action (e.g., Differential Con-
ductance or Delta), the Pulse Delta arm command will “un-arm” the other
action and arm Pulse Delta.
Differential Conductance
Differential measurements can be used to study the individual slopes of an I-V (or
V-I) curve. By applying a known differential current (dI) to a device, differential
voltage (dV) measurements can be performed. With dI and dV known, differential
conductance (dG) and differential resistance (dR) can be calculated.
Model 622x measurement process
This measurement process is used to eliminate the effects of thermal EMFs, and
a 3-point moving average calculation algorithm is used to provide more accurate
readings.
The differential measurement process is shown in
. The Model 622x is
configured to output a stepped sweep with a specified Delta, which is the differen-
tial current (dI). As shown in the illustration, Delta is added to and subtracted from
each subsequent step in the sweep. The solid line is the actual output of the
Model 622x.
As shown, each differential voltage calculation (dV Calc) uses the three previous
Model 2182/2182A A/D measurement conversions. Keep in mind that dI (Delta) is
the same for all calc points. With dI known and dV calculated, the Model 622x can
Summary of Contents for 6220 DC
Page 2: ......
Page 4: ......
Page 6: ......
Page 16: ......
Page 36: ...1 20 Getting Started Model 6220 6221 User s Manual Return to Section 1 topics...
Page 131: ...6 10 Averaging Filter Math and Buffer Model 6220 6221 User s Manual Return to Section 6 topics...
Page 148: ...A Specifications...
Page 167: ......
Page 169: ......
Page 170: ......
