Specifications

Figure 4-11. Cable length correction
Figure 4-12. Measurement error due to extended cable length
The cable length correction works for test cables whose length and propagation constants are
known, such as the Agilent-supplied test cables of 1, 2, or 4 m. If different types of cable in different
lengths are used, it may cause bridge unbalance in addition to measurement error.
V
Source resistor
DUT
Cable
Hc
pLpH
Lc
Range resistor
Range resistor
Cable
(a) Extended 4TP cables
(b) Effects of cable extension in low frequency region (≤ 100 kHz)
Z
hg
: An impedance determined by the capacitance of the Hcur and Hpot
test cables. This impedance does not directly affect the measured
impedance (Zm) because a leakage current flow through Zhg does
not flow into the Low terminal (I-V converter.) However, it degrades
measurement accuracy by decreasing the test signal level.
Z
lg
: An impedance determined by the capacitance of the Lcur and Lpot
test cables. Unless very long cables are used, this impedance does not
cause significant error in the measured impedance (Zm), because the
potential across Zlg is zero volts when the bridge circuit is balanced.
DUT
High Low
Z
hg
Z
lg
(C
hc
+ C
hp
)
(C
lc
+ C
lp
)
Source resistor
R
r
Edut
Err
Z
m
= R
r
Edut
Err
4-12