Specifications

Figure 4-10. Effect of contact resistance
Capacitance value C
x
D
e
rr o
r
T
wo -term inal contact
C
hp
Four-terminal contact
(c) Error of two-terminal and four-terminal connections
If R
H
= R
L
= R
hp
= R
lc
and C
hp
= C
lc
, D errors
of two-terminal and fou r-terminal contacts become the
same when C
x
= C
hp
.
This means that the two- terminal connection
is a better choice when the DUT capacitance
is smaller than cable capacitance
(C
hp
or C
lc
).
Error caused by R
hp
with C
hp
:
Phase error:
wC
hp
R
hp
[rad]
(b) Contact resistance in four-terminal connection
Magnitude error:
-1
1
1 +
w
2
C
hp
2
R
hp
2
C
x
C
hp
C
lc
H
c
H
p
L
p
L
c
R
hc
R
lc
R
hp
R
lp
Error caused by R
lc
with C
lc
and R
hp
with C
hp
:
D
erro r
= –w (C
hp
R
hp
+ C
lc
R
lc
)
C
x
HighLow
R
H
R
L
D
erro r
= w C
x
( R
L
+ R
H
)
(a) Contact resistance in two-
terminal connection
4-10