System and method for reducing undesired radiation generated by LSI

A method for reducing undesired radiation generated from an LSI, said method comprising:

• a first step of deriving a transfer function of undesired radiation, which is transmitted from an undesired radiation source in said LSI to a power source terminal connected to the outside of said LSI, on the basis of a circuit connection information for said LSI and a current waveform of said undesired radiation source of said LSI;
• a second step of setting a constraint on an impedance added in the vicinity of said undesired radiation source, an allowable level of undesired radiation at said power source terminal, and a frequency range to be considered;
• a third step of deriving undesired radiation at said power source terminal under said constraint;
• a fourth step of determining whether said undesired radiation derived at said third step is not higher than said allowable level in said frequency range;
• and
• a fifth step of changing said added impedance so as to reduce said undesired radiation to repeat said third and fourth steps when said derived undesired radiation exceeds said allowable level, and outputting said added impedance when said derived undesired radiation is not higher than said allowable level.