Question

I'm using HP capacitance measuring system .
I got Two data. One is pico parrad capacitance another is Hz frequency. But capacitance is lower when frequency is up. So capcitance value is not adjustable. What is real capacitance value?

Answer 1

Sorry for my poor English

Answer 2

@JoannaBlackwelder Any ideas?

Answer 3

@agent0smith

Answer 4

1kHz
388pF~390pF

10kHz
290pF

100kHz
145pF

1MHz
81.16pF

this is my data

Answer 5

@douglaswinslowcooper

Answer 6

Capacitance is stored charge per voltage. C = Q/V.

Perhaps at the higher frequencies there is only time for partial charge build-up before the polarity changes? That would lower Q and thus lower C.

Answer 7

Then, which is proper value to use? or i need more information?

Answer 8

It may be that capacitance is a function of frequency.
Try plotting the capacitance versus frequency, then extrapolate back to the value at frequency = 0.
This is the y-intercept if
capacitance = (slope) (frequency) + y-intercept.

Try log-log plot, since frequency ranges are powers of 10x.

Answer 9

Good

Answer 10

This is a plot on linear graph axes.

Try log (capacitance) vs. log(frequency) on linear axes.
Or capacitance vs. frequency on log-log axes.