Agilent Technologies 4339B - Page 219

4339B
High
Capacitance
DUT Measurement
Figure
7-3 shows
the measurement
conguration
for
this
application.
Figure 7-3.
Capacitance Measurement
Conguration
Where,
Rs Output
Resistance
of
the
4339B
Rx P
arallel
resistance
of
the
DUT
Cx P
arallel
capacitance
of
the
DUT
Ri
Input resistance
of
the
4339B
Ro
A
dditional
Series
Output
Resistance
of
the
16339A
Necessary
charging
time
is
approximately
led
by
following
equation.
t
c
=
0

2
l
n
(
X
100
2
R
s
+
R
i
+
R
o
R
x
)
Where
,
t
c
:
Charge
time
[s]
X
:
Measurement
Error
[%]

= C
x
2
( R
s
+
R
i
+
R
o
)
Generally
,when
measuring these
types of
DUT's as
described in
this
section,
you
should
expect
a
charging
time
of
more
than
10
or
20
times 
.
Note
The charge time of an ideal capacitor is shown in this section. Generally
,you
should consider characteristics of a
dielectric for the estimation of the actual
charge time
.
Note
When the additional
series resistor value is too high, its resistance can not be
disregarded and it causes additional measurement error
.
Measurement Basics 7-7