PSM3750 Quick User Guide
Page 52
8.3 LCR
–
Impedance Meter
Impedance Analysis
–
an overview
Real Components are never ideal resistors, capacitors or inductors because of
unwanted parasitic effects arising from their construction.
It is useful to model a real component as an appropriate combination of ideal
resistance, capacitance and inductance. For example, a real inductor at a
frequency below its resonant frequency may be modelled as a pure inductor with
a series resistor; a real resistor may be modelled as a pure resistor with a series
inductance or by a pure resistor with a parallel capacitance; a capacitor is most
commonly modelled as a pure capacitor with a series resistance.
The parameters of real components vary with the conditions of frequency and
voltage/current under which they are used.
In many cases, components are used under conditions where the parasitic
effects of the component become critical and must be measured reliably over a
wide range of operating conditions.
The impedance is analysed by measurement of the complex impedance,
Z
under
controlled conditions of frequency and voltage or current:
Z = V / I
Where
V
is the voltage across the component
I
is the current through the component
Z, V
and
I
are complex values which may be represented as magnitude and
phase or by in-phase and Quadrature components. The LCR measurement is
performed by the PSM3750 using a discrete Fourier transform (DFT) at the
frequency of operation. This gives the complex impedance directly in the form of
an in-phase component and a Quadrature component.
It is important to characterise the component over all the frequencies that are
relevant for a given application. For this reason the IAI2 can be used in
conjunction with the PSM3750 to sweep across a frequency range.
Summary of Contents for PSM3750 NumetriQ
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