Keithley 237

SECTION2
Operation
+
IE-
Delay~
IE-
Delay~
IE-
Delay~
Level
_j>
)(
)(
)(
•
IE-
Delay~
)(I
. . .
Bias-?
t t t
t...._
__
Measure
Point#1
X
=
Measurement point
Figure
2-31.
Fixed
Level
Waveform
Measure
Point#2
Measure
Point#3
. . . .
-
•
Measure
Point#1000
~Delay~
t-Stop
J
Step
1
~Delay~
.;
_T
Step
~Delay~
1
~Delay~
Start
----+r----.......J,f-1.
Bias---+
___
_..
I
_T
Step
1
I
Measure Measure
X
=
Measurement point
Figure
2-32.
Linear
Staircase
Waveform
Logarithmic
Staircase Sweep: This
sweep
is
similar
to
the preceding staircase sweep, however the steps are
done
on
a logarithmic scale as
shown
in
the
example
sweep
in
Figure 2-33. The programmable parameters
of
this sweep include;
start
level, stop level,
and
measure
points
per
decade, delay, bias,
and
source range.
When this sweep
is
triggered to start,
the
output
will
go
from the bias level to
the
start
source level. The
start
level
and
the
programmed
points/
decade
(5,
10,
25
or
50)
de-
termine
the
step
values for
the
staircase. The
Source
2-56
+
I I
Measure
Measure
Measure
Unit
will
automatically select step values
that
will
provide
symmetrical steps (on log scale)
through
each source decade
to
the
stop source level. The
sweep
example
in
Figure 2-33
is
programmed
for 5
points/
dec-
ade. Thus,
the
Source Measure
Unit
selects step values
that
provide
a five-step staircase
through
each of
the
two
source decades.
The time
duration
at
each
step
of
the
sweep
is largely de-
termined
by
the
programmed
delay. A measurement oc-
curs after
the
delay
on
each step. After taking the last