A method of designing a semiconductor integrated circuit includes defining
a tolerable range in which an operating temperature and an operating
power supply voltage of a semiconductor integrated circuit are allowed to
vary, computing a target temperature and a target power supply voltage
that cancel variation in circuit characteristics caused by process
variation of the semiconductor integrated circuit, separately for each
circuit characteristic responsive to the process variation, and designing
the semiconductor integrated circuit such that the semiconductor
integrated circuit properly operates with any temperature and power
supply voltage within the tolerable range based on an assumption that the
semiconductor integrated circuit is to operate within the tolerable range
centered substantially at the target temperature and target power supply
voltage.