Phase difference capacitance measurement-in progress

I'm am attempting to use the phase delay in a signal to measure precise levels of small capacitance for a capacitive displacement sensor meant to measure precise (less than nanometer scale) movements in parts of a precision machine. The two phases are converted to a pulsed output with the width of the pulse corresponding to a given capacitance and therefore distance. This pulse width will be used to charge a capacitor through a resistor, giving a near linear slope with the ending voltage corresponding to how long the pulse was giving me an immediate response to the amount of displacement of the capacitive displacement sensor. This sloped output I am still working on trying to save to an analog "memory" in the form of an option amp capacitor pair, and to reset the original capacitor charged by the pulse width from the phase difference.

published 7 years ago