SECTION2
Operation
tering,
and
by
disabling default delay. Note that the
"PULSE
TIME NOT
MET"
message is displayed when-
ever AUTORANGE is enabled.
This
indicates that on
and
off times will most likely
not
be
met
when
a measure
range change occurs. To ensure exact pulses, disable
AUTO
RANGE.
Points/Decade: The points
per
decade parameter is used
for logarithmic sweeps. The number of points
(5,
10,25
or
50)
dictate the number of steps
and
measurements that
will
occur
in
a source decade. The actual values of the
steps are also dependent
on
the start value of the staircase
sweep. The
Source Measure
Unit
automatically calcu-
lates the step values so that a symmetrical staircase (on
log scale)
will
occur through the source decades.
Range: Available source ranges for sweeps include
AUTO,
BEST
FIXED,
and
the individual fixed ranges.
With AUTO
range selected, the Source Measure Unit
will
always go the lowest possible source range while the
sweep is in progress. With
BEST
FIXED
range selected,
the Source
Measure
Unit
will select the range that
will
ac-
commodate the largest source level before the sweep is
triggered to start. The Source
Measure
Unit
will
stay
on
this
range throughout the entire sweep.
By
avoiding
source range changes, overall speed is improved. The us-
er, of course, can select any available fixed source range.
However,
if
the selected range cannot accommodate a
source level, the message ''VALUE OUT OF RANGE"
will
be briefly displayed
when
saving sweep parameters,
and
range
will
default to
BEST
FIXED.
Note that source
AUTO
range cannot be selected for the pulse sweep
waveforms.
If
a sweep is created using a fixed source range, the
"BEST
FIXED
RANGE"
will always
be
displayed as the range
parameter when CREATE is enabled.
If
a
new
sweep is
not created
(CREATE
disabled), the sweep
will
use the
previously selected fixed source range.
Start
and
Stop:
All staircase sweeps use start
and
stop pa-
rameters. The staircase begins at the start level
and
steps
to the stop level.
In
all cases, the
output
returns to the bias
level after the stop level is measured.
+
Step:
The step parameter is used for the linear staircase
and
linear staircase pulse sweeps. Step
is the value that
each subsequent source level
or
pulse increments
or
dec-
rements in the staircase.
2.19.2
General
Procedure
The general procedure for defining a sweep is provided
by
the following procedure. For many users,
this
infor-
mation is enough to define any of the available sweep
waveforms. Others
may
wish to utilize the detailed step-
by-step procedures provided
in
paragraphs 2.19.4
through 2.19.9.
Referring to the appropriate sweep waveform
(Figure
2-31
through Figure 2-36), perform the following
steps to define the parameters of a sweep.
Step
1.
Select Source
To sweep (source) voltage, the
Source
Measure
Unit
must
be
in
Source
V Measure
I.
Conversely, to sweep (source)
current, the Source
Measure
Unit
must
be
in
Source
I
MeasureV.
Step
2.
Enable
Sweep
CREATE
The currently defined sweep waveform
will
be dis-
played.
If
you
wish to define a different sweep
waveform, proceed to step
3.
The parameters of the displayed sweep waveform can be
displayed
by
using the rotary knob.
If
you
are going use
this sweep as
it
is currently defined, press
CREATE
and
then ENTER The Source Measure
Unit
will
return to the
source-measure display state. To change one
or
more pa-
rameters of this sweep waveform, proceed to step
4.
Step 3.
Select Sweep
Waveform
Figure 2-37 shows the sweep waveform selections. Use
the
SELECT
buttons to display the desired sweep
waveform
and
then press ENTER.
~
SELECT
t>
FIXED
LEVEL
I I
LINEAR
STAIR
I
LOG
STAIR
I
._I
_....;P;....;U;.;;;L""SE;;_____.
I
LIN
STAIR
PULSE
I I
LOG
STAIR
PULSE
I
Figure
2-37.
Sweep
Waveform
Selections
2-62
+
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