Patent ID: 11881381
Assignee: LAM RESEARCH CORPORATION
Field: Measurement (Instruments)
Classification: CPC H  C  G | IPC C  G  H

Claim 8:
9. The method of claim 3, wherein:
aa) includes generating an alternating voltage (Vin) as the first signal at the first frequency (ω) using an oscillator, an output of the oscillator being coupled to a first terminal of the capacitor through at least a first impedance (z1) and a second impedance (z2) that are each in series with the capacitor, the output of the oscillator also being coupled to a second terminal of the capacitor through at least a third impedance (z3) that is in series with the capacitor;
cc) includes measuring as the measured filtered signal a current or voltage at a node coupling the first impedance (z1), the second impedance (z2), and the third impedance (z3), wherein the measured filtered signal represents an imbalance between:
a first impedance combination comprising the first impedance (z1) and the second impedance (z2), and a second impedance combination comprising the third impedance (z3) and an impedance of the capacitor (zC); and

dd) includes converting the measured filtered signal to the measured capacitance value (C) based in part on a ratio z1/z2=z3/zC, where zC=1/jωC.