28 | Keysight | E4991B Impedance Analyzer - Data Sheet
Typical Effects of Temperature Change on Measure-
ment Accuracy
When the temperature at the test port (7-mm connector) of the high temperature cable
changes from the calibration temperature, typical measurement accuracy involving
temperature dependence effects (errors) is applied. The typical measurement accuracy
is represented by the sum of error due to temperature coefficients (E , Y and Z´),
´
´
a
o
s
hysteresis error (Eah , Yoh and Zsh) and the specified accuracy.
Conditions
Temperature compensation:
Temperature compensation data is acquired at the same temperature points as
measurement temperatures.
Typical measurement accuracy (involving temperature dependence effects)1:
|Z|, |Y|: ± (Ea + Eb + Ec + Ed) [%]
q
(Ea + Eb + Ec + Ed)
: ±
[rad]
100
Where, Ea, Eb = Refer pages 25 and 26.
Ec
Ed
=
=
E × ΔT + Eah [%]
´
a
Z × ΔT + Z
´
s
sh + (Yo´× ΔT + Yoh) × |Zx| × 100 [%]
|Zx|
Where,
|Zx|
Here, E , Z and Y are given by the following equations:
=
Absolute value of measured impedance
Figure 35. Typical frequency characteristics of temperature coefficient,
(Ec+Ed)/ΔT, when |Zx|= 10 Ω and 250 Ω2.
´
´
´
o
a
s
Without temperature compensation
With temperature compensation
1 MHz ≤ ƒ < 500 MHz
500 MHz ≤ ƒ ≤ 3 GHz
Ea´
0.006 + 0.015 × ƒ [%/°C]
0.006 + 0.015 × ƒ [%/°C]
0.006 + 0.015 × ƒ [%/°C]
Zs´
Yo´
1 + 10 × ƒ [mΩ/°C]
0.3 + 3 × ƒ [µS/°C]
1 + 10 × ƒ [mΩ/°C]
0.3 + 3 × ƒ [µS/°C]
5 + 2 × ƒ [mΩ/°C]
1.5 + 0.6 × ƒ [µS/°C]
1. See graphs in Figure 35 for the calculated values of (Ec+Ed) exclusive of the hysteresis errors Eah, Zsh and Yoh, when
measured impedance is 10 Ω and 250 Ω.
2. Read the value of Δ|Z|%/°C at the material measurement frequency and multiply it by ΔT to derive the value of (Ec+Ed).
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