Patent ID: 7292054

Claim:
A method of measuring RF (radio frequency) impedances, comprising: measuring package RF signals between terminals formed on front and back surfaces of a package substrate; measuring calibration RF signals between terminals formed on at least one calibration substrate; determining RF impedances of said package substrate from the package RF signals; determining phase differences corresponding to a thickness of said package substrate and distances between said terminals on the front surface or the back surface of said package substrate from the calibration RF signals; and calibrating said RF impedances based on said phase differences, wherein a processing unit is configured to measure the package RF signals between terminals formed on a package substrate, to measure the calibration RF signals between terminals formed on at least one calibration substrate, to determine the RF impedances of said package substrate from the package RF signals, and the phase differences corresponding to a thickness of said package substrate and the distances between said terminals on said package substrate from the calibration RF signals, and to calibrate said RF impedances based on said phase differences.