Patent ID: 6768952
Filing Date: 2004-07-27
Classification: G01R,G06F

Abstract:
A method of measuring impedance in a system having a microprocessor, comprising:holding the microprocessor in reset mode and measuring a first current level while providing a clock to the microprocessor at frequency FCLK, and measuring a second current level while providing the clock at frequency FCLK/N, where N is a positive integer; while holding the microprocessor in reset mode and toggling the clock frequency between FCLK and FCLK/N, generating a periodic current waveform and measuring the voltage at at least one port in the system a plurality of times to obtain at least one set of voltage measurements, and averaging the plurality of sets of voltage measurements; varying FCLK and determining a Fourier component of the averaged voltage measurements to determine clock frequency-dependent noises, and 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.