A 300 MIPS/W RISC core processor with variable supply-voltage scheme in variable threshold-voltage CMOS

A 300 MIPS/W RISC core processor with variable supply-voltage (VS) scheme in variable threshold-voltage CMOS (VTCMOS) is presented. Performance in MIPS/W can be improved by a factor of more than two with no modification in the RISC core except for substrate contacts for the VTCMOS. From a 3.3 V external power supply the VS scheme automatically generates minimum internal supply voltages which meet the demand on its operation frequency.