Chapter
Accuracy and Calibration
How to Assess and Control the Accuracy
The accuracy achieved by the Model Z9216 Digital LCR Meter depends on several factors. In this
chapter, equations are given for estimating the accuracy of a specific measurement, and procedures
are given for calibrating the meter.
Accuracy Specifications
Note: The accuracy of the Model Z9216 that is stated in this chapter is valid for the following
conditions: (a) a warm-up time of at least 30 minutes, (b) a temperature of 23°C ± 5°C, (73°F± 9°F) (c)
the use of the built-in fixture, and (d) the completion of the open and short circuit calibrations. In
addition, the component being measured must have the following characteristic: D < 0.1 for a
capacitor, Q < 0.1 for a resistor, or Q > 10 for an inductor.
General Accuracy Equation
The accuracy of a measurement is a function of the “basic impedance accuracy” at the specific
frequency, measurement rate, signal amplitude, and the impedance of the device under test (DUT)
relative to the measurement range. The basic instrument accuracy can be determined from graphs
given below. Additional factors affecting the accuracy are related to the measurement conditions and
the impedance of the DUT. From these, the accuracy of a particular measurement in its optimal
range is calculated. See below for the effects on measurements made out of an optimal range.
The basic equation for impedance measurement accuracy equation is given by:
A
z(measured)
% = ± [A
z
× K
i
× K
v
+ 100 × (K
h
+ K
l
)], where (1)
A
z
= the basic impedance accuracy from Figure 2-1, which should be multiplied by two if the unit
is in constant voltage mode. Figure 2-1 is based on the fact that the best accuracy occurs
when the impedance to be measured is greater than ¼ the source resistance and less than 4
times that resistance, and when the test frequency is 1 kHz or less.
K
i
= integration time factor, as given in Table 2-1.
K
v
= drive voltage error factor, as given in Table 2-2. Note from Table 2-2 that K
v
is defined as
equal to 1.0 for the primary drive voltages (1.0, 0.5, and 0.25 Vrms).
K
h
, K
l
= extreme range error terms, as given in Table 2-3. Note from Table 2-3 that K
l
is
negligible for impedances above 100 Ω and K
h
is negligible for impedances below 1 kΩ, both
at all frequencies.
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