HP 4262A - Measurement Error

2) Influence on high capacitance and high in-
ductance measurements.
When a high inductance (a high capacitance)
is measured, the residual factors in the test
jig also contribute a measurement error.
The affect of stray capacitance or residual
inductance on measurement parameters are:
Stray capacitance — Offsets high inductance
measurements.
Residual inductance —QOffsets high capacitance
measurements.
These measurement errors increase in
proportional to the square of the test signal
frequency. The effects of the residual
factors can be expressed as follows:
Lx
1 - w2LxCst
(Lm—Lx,\\,
Lm
Lm =
or »2LxCst)
In a 10kHz measurement, for the measure-
ment error to be less than 0.1%, the pro-
duct of Cx and Lres (Lx and Cst) should be
less than 0.25 x 10-12, The relationship
between the residual factors of the test jig
and measurement accuracies are graphically
shown in Figure 3-4.
The 4262A ZERO ADJ controls cover the following
capacitance and inductance offset adjustment
ranges:
C ZERO ADJ: up to 10pF
.
Cx
:
Cm
=
=
3CxLres
L
ZERO
ADJ:
up
to
1pH
Cm
-Cx
An
offset
adjustment
should
always
be
performed
or
(
Cm
~
w2CxLres)
before
measurements
are
taken.
IOH
100uF
<
<
I
T
\;
\
\
Test
Signal
|
IOKHz
N
\
\\
N
N
N
\
\
NN\
N
NN
TN
L
PN
N\
Ne
N
%
@
3
AN
\e)
-
9
g
\
Qso
)
o
2
8
8
\Q,?)
A
-
AVEAN
o1
|
\\
\\
N
N
0.0l
Residual Inductance
O.l
Stray Capacitance
0.1 luH
] 10pF
Figure 3-4. Measurement Error due to Misadjusted ZERO ADJ Controls.
3-11