System and method of measuring low impedances

摘要

A method comprises generating first and second current levels and measuring the first and second current levels. The method further comprises alternately generating the first and second current levels repeatedly to generate a periodic current waveform, and measuring the voltage at at least one port in a system a plurality of times to obtain a plurality of sets of voltage measurements. The plurality of sets of voltage measurements are averaged. The method further comprises alternately generating the first and second current levels repeatedly at a predetermined number of different clock frequencies, determining a Fourier component of the averaged voltage measurements to determine clock frequency-dependent noises, removing the clock frequency-dependent noises to generate a filtered average voltage, and determining an impedance by dividing a Fourier component of the filtered average voltage by a Fourier component of the periodic current waveform having alternating first and second current levels.