Patent ID: 6911827

Claim:
A method of measuring impedance in a system having a microprocessor, comprising: generating a first current level in the system via operation of the microprocessor; measuring the first current level; generating a second current level in the system via operation of the microprocessor; measuring the second current level; alternately generating the first current level and the second current level repeatedly via operation of the microprocessor to generate a periodic current waveform; measuring the voltage at, given the periodic current waveform, at least one port in the system a plurality of times to obtain a plurality of sets of voltage measurements; averaging the plurality of sets of voltage measurements; generating the first and second current levels 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 of a power supply system on the microprocessor 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.