Patent ID: 8484606

Claim:
Method for calculating voltage fluctuation amount of power supply voltage generated in a semiconductor device corresponding to mounting manner of a decoupling capacitor mounted on a power supply input unit to the semiconductor device, the method comprising: (a) providing an internal circuit in the semiconductor device for detecting fluctuation of the power supply voltage generated in the semiconductor device, the fluctuation of the power supply voltage is detected to indicate a condition under which the internal circuit has stopped operation to indicate that said internal circuit is stuck by the fluctuation of the power supply voltage generated in the semiconductor device; (b) specifying a first relationship between the power supply voltage of the semiconductor device and maximum operable frequency of the internal circuit, upon the fluctuation of the power supply voltage being detected by changing the power supply voltage of the semiconductor device and the operating frequency of the internal circuit; (c) specifying a second relationship between the maximum operable frequency of the internal circuit and the mounting manner of the decoupling capacitor, upon the fluctuation of the power supply voltage being detected by changing the mounting manner of the decoupling capacitor and the operating frequency of the internal circuit; (d) specifying, by a controller coupled to the internal circuit in the semiconductor device, the power supply voltage of the semiconductor device corresponding to the mounting manner of the decoupling capacitor based on the first relationship and the second relationship; and (e) calculating the fluctuation amount of the power supply voltage from predetermined power supply voltage based on the specified power supply voltage.