+
SECTION3
IEEE-488
Reference
! !
i i
I!! I!!
_h
~
~
~~Delay
~Delay'T'I
I!!
!!!I._
_h
.~
t-Stop
i jr-
Delay
~DelayT'
Volts
6
4
I._
_h
.~
~
r-
Delay
~Delay
1
.,
!
2
Start~
-*-
0
Bias~
I.__
_
__.
It--
tON
-+
toFF
1
Sweep
Point
1
2
3
4
5
6
Source
Value
2V
OV
4V
ov
6V
ov
tON/IoFF
100msec
70msec
100 msec
70msec
100 msec
70msec
Figure
3-10.
Linear
Stair
Pulsed
Sweep
Waveform
04,2,6,2,2,100,
70
A linear stair pulsed sweep is shown
in
the second programming example.
Logarithmic Stair Pulsed Sweep ( Q5)
The
QS
command selects a logarithmic stair pulsed sweep. (See Figure 3-11.) This
sweep is much like the linear stair pulsed sweep
(Q4) excepts that
it
is performed
logarithmically like the
Q2log
stair sweep. Each pulse consists of two S-0-M cycles,
one during the on-time
and
another during the off-time.
The amplitude of the first pulse on-time is specified
by
the "start'' parameter. The
"stop" parameter determines the amplitude of the last pulse during the on-time.
During the off-time, the pulse amplitude is the same as the bias level
when
the sweep
was created. The start
and
stop values determine the slope of the ramp.
The "points" parameter specifies the number
of
pulses
per
decade. The pulses are
evenly spaced within the log scale of each decade that the source encompasses.
As with all sweeps, the source range is specified
by
the "range" parameter
(autorange is not permitted).
The
on
and
off times are specified
by
toN
and
toFF,
where
toN
is the duration of the
sweep level
and
toFF
is the duration
of
the bias level. From the values of
toN
and
toFF,
the instrument calculates sweep delays for the
on
and
off-times.
It
takes into account
other instrument operating parameters, such as integration time, that have
an
effect
on
the S-D-M width.
+
3-53
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