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I can not get my head around what a LCR meter measures. My LCR meter measures my device (MIS) which is displayed as C_p and G_p (other components can be neglected). My LCR meter displays C_p, G_p, the applied voltage and frequency. I guess the capacitance of my MIS structure is C_p, but I do not understand why it also displays G_p, why should this be relevant to me if I only want to measure the capacitance?

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  • \$\begingroup\$ Did you tell the LCR meter to ignore conductance? I would expect that this value will be very small if you have a good insulator. \$\endgroup\$ Commented Feb 5, 2021 at 18:40

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It's measuring a complex impedance at one or more frequencies and interpreting the measurement as those lumped components. The result is always two numbers at a single frequency, so it should display both (Capacitance and conductance in this case).

If a single-frequency impedance measurement is interpreted as a different circuit, for example parallel RC, the numbers will both change.

The value also gives you an idea of the reliability of the measurement. If the conductance component of the impedance is very small compared to the susceptance of the capacitance then the latter will be more reliable than the former because small phase angle differences will greatly affect the former.

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  • \$\begingroup\$ To clarify your last sentence, you mean if C_p << G_p than this is a hin for a reliable measurement? \$\endgroup\$
    – Maxim
    Commented Feb 5, 2021 at 19:44
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    \$\begingroup\$ No, it depends on the measurement frequency so you have consider the impedance or susceptance of the capacitor at that frequency relative to the resistance or conductance. You would typically pick a measuring frequency appropriate for the situation. \$\endgroup\$ Commented Feb 5, 2021 at 20:19

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