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Section 11: Pulse Source-Measure Concepts
Load Line Effect Compensation: Coping with the Load Line Effect
There are three common ways of working with this effect. The simplest one is to program the DUT
load into the pulse card channel using the pulse_load command (see
commands), or setting the Pulse Load value in the Kpulse virtual front panel (see User Manual,
Section
waveform, specified by pulse_vlow and pulse_vhigh, has the desired levels. This works well for
high impedance devices or device terminals (R
field effect transistor (FET). Unfortunately, many times R
example of a varying R
changing from point-to-point and sweep-to-sweep.
There is basically only one way to handle this situation, with two different levels of implementation.
In general, assume the DUT is a FET. If the test consists of a single, or limited number of gate and
drain, test points, the necessary voltages can be determined by pre-characterizing each unique
set of test conditions.
This pre-characterization requires some way to measure the pulse heights, which is typically done
using an oscilloscope and an iterative trial and error approach. Each desired test voltage needs to
be measured, with the pulse levels adjusted until the desired voltage is reached. Record each
pulse level required to reach the desired V
An alternate method requires some type of software algorithm, in addition to the oscilloscope. The
software, such as a 4200 user test module (UTM), would take V
appropriate adjustments to reach the desired V
software algorithm would perform the iterations and handle all the measurements and calculations.
This type of software algorithm approach is used in the optional pulse IV packages available for
the 4200-SCS, such as the 4200-PIV-A and 4200-PIV-Q. Note that the algorithms in these
packages are not available for general purpose use and have been customized for the source/
measure approach and system interconnect unique to each package.
NOTE
NOTE
11-20
5). The pulse card will calculate the appropriate V
is the drain-source resistance during a V
DUT
Basic Oscilloscope hardware and concepts are covered in the User Manual,
(Oscilloscope).
The 4225-PMU has built-in load line effect compensation. For details, see
effect compensation (LLEC) for the
Return to
INT
= 1 k Ω), such as the gate terminal on a CMOS
DUT
DUT
levels.
DUT
. This is also an iterative approach, but the
DUT
PMU.
Section Topics
Model 4200-SCS Reference Manual
Section 8
for the pulse card
to output so that the V
DUT
is not known or varies. A key
-I
sweep, where R
D
D
readings then determine the
DUT
Load line
4200-901-01 Rev. S / May 2017
pulse
is
DS
SCP2
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