I'm looking for a highly accurate phase detector for my capacitive sensing application.
In the application, the capacitance is in the range of 1 ~ 10 pF.
I've been able to get the capacitance via analog device's AD7745.
However, I was requested to have the dissipation factor measured as well.
I've been trying to seek a chip to do the job, unfortunately not yet.
I've came up with the idea of using a phase detector, with the information of which, I'll be able to calculate an approximate value of dissipation factor myself later on.
So my question is, is there such a phase detector that can detect the phase difference between the voltage and current across the capacitive sensor with a very high accuracy?
with accuracy I mean: the capacitor is a nearly ideal capacitor with dissipation factor of less than 0.001, so the most interesting part of phase difference is between 89 ~ 90 degrees…
The interested frequency range is DC ~ 1Mhz.
thanks !
Best Answer
You can use the Analog Devices AD8302 phase detector, you just need to tune it up to read between 89-90 degrees thus a sensitive and calibrated micro-voltmeter to give you some good measurement resolution.
Also it gives you not only the phase angle but also voltage difference in dB, thus it can give out vector values which can be transformed into rectangular values. Lotsa flexibility.