Actually, Rs and Rp are existed in the equivalent circuit of capacitor or inductor. If
the capacitor is small, Rp is more important than Rs. If capacitor is large, the Rs is more
important also. Therefore, use parallel mode to measure lower value capacitor and use
series mode to measure higher value capacitor. For inductor, the impedance relationship
is different from capacitor. If the inductor is small, Rp is almost no effect. If inductor is
large, the Rs is no effect also. Therefore, use series mode to measure lower value
inductor and use parallel mode to measure higher value inductor.
Open/short calibration
The ES51919/ES51920 chipset provides the open/short calibration process to get the
better accuracy for high/low impedance measurement. The purpose of open/short
calibration is to reduce the parasitic effect of the test fixture.
Z
M
is defined as total impedance measured to DUT by the special test fixture which
1
has some parasitic impedance. Z
M
= (Rs + jωLs) + (
|| Z
DUT
)
Go
+
j
ω
Co
Z
OUT
is the target impedance user wants to realize. It is necessary to use the
open/short calibration process to cancel the effect of Rs + jωLs and Go+jωCo.
Ver 2.1
4
12/03/01
CYRUSTEK [ Cyrustek corporation ]
