Patent ID: 7635986

Claim:
A power source noise measuring device comprising: a first mutual inductor pair placed inside an integrated circuit, said first mutual inductor pair including (i) a first inductor connected between power source voltages of the integrated circuit and (ii) a second inductor arranged opposite the first inductor, the both ends of which second inductor are connected to between external output terminals of the integrated circuit; a variable power source provided outside the integrated circuit; a second mutual inductor pair placed inside the integrated circuit, said second mutual inductor pair including a third inductor connected to said variable power source and a fourth inductor arranged opposite the third inductor, the both ends of which fourth inductor are connected to external output terminals of the integrated circuit; an adjusting unit which adjusts voltage of said variable voltage source in such a manner that a first voltage waveform output from the second inductor of said first mutual inductor pair via external output terminals is the same or approximately the same as a second voltage waveform output from the fourth inductor of said second mutual inductor pair via external output terminals; and a power source noise measuring unit which measures power source noise of the integrated circuit on the basis of voltage of said variable power source adjusted by said adjusting unit.