Patent ID: 7483799

Claim:
A method for sampling a power supply current value for frequency analysis of the power supply current flowing in an integrated circuit when a test signal is applied to said integrated circuit, comprising steps of: (a) obtaining pre-determined circuit information of said integrated circuit; (b) starting generation of a pre-established power supply voltage and applying said power supply voltage to a power supply terminal of said integrated circuit; (c) starting generation of a test signal, and starting application of said test signal to an input/output terminal other than a power supply terminal of said integrated circuit; (d) observing a value of a power supply current supplied to said integrated circuit, and generating a power supply current value signal indicating said power supply current value; (e) starting sampling of said power supply current value signal simultaneously with the start of the application of said test signal to said integrated circuit; (f) ending sampling of said power supply current value signal when an amount of extension time determined based on said circuit information has elapsed after the end of application of said test signal to said integrated circuit; and (g) performing a Fourier transformation on all data obtained by said sampling, and obtaining a frequency spectrum of said power supply current value signal.