Hi there, I would like to measure the inductance and capacitance of a surface mount device at microwave frequencies using a VNA, such as the 8510C. I have done some searching and come up with the App note 5989-5935EN, but I don't think it solves my problem, as it seems to assume that the devices have a constant capacitance and inductance across the frequency range of interest, while my devices do not. It should be possible to measure the inductance and capacitance (and resistance) of the device using S11 and S21 measurements in a similar way that we can measure permittivity and permeability of materials using 2 port measurements, however I have been unable to find any references that explain the way to do this. The problem lies in finding a way to separate the imaginary component of impedance into its inductive and capacitive parts.

Any help appreciated...

Andrew

Any help appreciated...

Andrew

The sign of the imaginary component only shows which term is dominant, doesn't it? Just because the sign is negative, it doesn't mean the inductance of the device is zero, and vise versa (as far as I know). I want to be able to measure the inductance and capacitance of the device across the entire frequency range so I can use the measured values in computer simulations.

Using a single port measurement doesn't give you enough information to be able to separate the values of C and L in im(Z).

Actually, it does, if you measure at more than 1 frequency. In fact, measuring at only one frequency, you cannot tell if the the elements are pure L, pure C or some combination. One solution to this problem is to measure over several frequencies and compute model terms. This was done to find the models associated with unknown- or poorly known calibration standard values in this patent: http://patft.uspto.gov/netacgi/nph-Pars ... /6,643,597

similar methods could be used to characterized unknown devices.

Thanks,

Andrew