System and method of measuring low impedances

• Main Authors: HOUGHTON, CHRISTOPHER L, LAURENT, JAMES J. ST, KANTOROVICH, ISAAC
• Format: Patent
• Language: Chinese; English
• Published: 01.05.2004
• Subjects: CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

A method (56) of measuring impedance in a system having a microprocessor (14) comprises holding the microprocessor (14) in reset mode and providing a clock to the microprocessor at a frequency FCLK (57, 58) while measuring a first current level, providing the clock at frequency FCLK/N (59, 60) while measuring a second current level, measuring the voltage at a plurality of ports in the system a plurality of times to obtain a plurality of sets of voltage measurements (61, 62, 63) while holding the microprocessor in reset mode, toggling the clock frequency between FCLK and FCLK/N, and generating a periodic current waveform. The plurality of sets of voltage measurements are averaged. The method further comprises 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 (64), and determining an impedance by dividing a Fourier component of the filtered a