+
SECTION3
IEEE-488
Reference
For all sweeps, the last programmed bias value becomes the
output
level of the
unit
before
and
after the sweep. When a pulsed sweep waveform
is
created
or
appended,
the last programmed bias value also becomes the
output
level
during
the
toFF
and
idle
times
of
the sweep. Therefore, the B
command
should
precede
or
reside
in
the same
command string as the
Q
command,
but
not
in
a separate command string after the
Q
command.
Once a sweep list
is
created,
it
is
stored
in
battery backed-up memory for future use.
However, one
and
only one sweep list can
be
saved. Creating a
new
sweep list de-
stroys the old sweep list.
Fixed Level
Sweep
(QO)
The
Q0
command selects a fixed level (or constant) sweep.
(See
Figure
3-6.)
The pa-
rameters for this command create a sweep
at
a specified source value of "level". The
"count'' parameter specifies the
number
of measurements to take
and
store
in
the
sweep buffer. The "delay'' parameter specifies the desired delay time before each
measurement.
An
appropriate source "range"
is
also specified. Use
a fixed level
sweep instead of
the
de
function
if
you
want
time stamping of the measurements.
Volts
e
e e
::::J
::::J ::::J
Ill
Ill
Ill
Cl)
+~+
Cl)
f
Delay
+~+
Delay
Delay
t~~
5
J
L
0
Bias~
Sweep
Source
Sweep
Point
Value
Delay
00,
5, 2,
100,3
1
5V
100
msec
2
5V
100
msec
3
5V
100
msec
Figure3-6.
Fixed
Level
Sweep
Waveform
Linear
Stair
Sweep
(
Ql)
The
Ql
command selects a linear stair sweep.
(See
Figure 3-7.) The staircase starts
at
a specified source value of "start"
and
ends
at
the specified "stop" source value, in-
clusively. The "step" parameter specifies the increment of each staircase step
and
is
interpreted as
an
absolute value,
with
the start
and
stop values determining
the
slope
of the ramp. The larger of the
start/
stop values also determines the required resolu-
tion of the step (e.g.,
with
a start of
lOrnA
and
a stop
of
lOOmA,
the step
must
be
no
less
than
lOJ.lA
or
a step
of
0
will
be
used, yielding a buffer filled
with
lOrnA
source
values).
+
3-49
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