Semiconductor integrated circuit and control method for the same

A semiconductor integrated circuit comprising:

• a user circuit configured to include a plurality of circuit modules each containing an operation ratio control circuit;
• and
• a power supply noise suppression circuit operably coupled to the user circuit and configured to judge an amount of current fluctuation occurring in the user circuit by monitoring an operation ratio of each of the plurality of circuit modules, and to control, via each of the operation ratio control circuits, the operation ratio of a corresponding one of the circuit modules in accordance with a result of the judgment of the amount of current fluctuation, wherein
• the power supply noise suppression circuit comprises:
• an operation ratio monitoring unit configured to receive a signal indicating high correlation with a power value produced during operation of each of the plurality of circuit modules, and to output an operation ratio information signal carrying operation ratio information;
• a current evaluation unit configured to receive the operation ratio information signal and to output a current value information signal carrying corresponding current value information;
• a current fluctuation amount judging unit configured to receive the current value information signal and to output a current fluctuation amount limit exceeded signal indicating that the amount of current fluctuation has exceeded a fluctuation limit value;
• and
• an operation ratio control unit configured to receive the current fluctuation amount limit exceeded signal and to supply an operation ratio control signal to the operation ratio control circuit, wherein
• the current fluctuation amount judging unit judges whether a previous first current value in the user circuit is not larger than a first limit value defining a lower limit or is not smaller than a second limit value defining an upper limit, wherein
• when the first current value is judged to be not larger than the first limit value, the current fluctuation amount judging unit then judges whether a current value difference taken between the first current value and a present second current value is not smaller than the fluctuation limit value, and
• when the first current value is judged to be not smaller than the second limit value, the current fluctuation amount judging unit then judges whether the current value difference taken between the first current value and the present second current value is not greater than the fluctuation limit value.