Optimum device parameters and scalability of variable threshold voltage complementary MOS (VTCMOS)

The optimum device parameters of variable threshold voltage complementary m etal oxide semiconductor (VTCMOS) have been investigated by means of device simulation and its scalability has been discussed. The optimum body effect factor depends on the relationship between the substrate bias and the supp ly voltage. It is shown that the VTCMOS scheme aiming at extremely low stan d-by power will fail as the device size and the supply voltage are scaled. The advantage of VTCMOS will be its high speed, and the VTCMOS will be esse ntial in high-speed circuits operating at a low supply voltage in combinati on with another low stand-by power scheme such as the insertion of leak cut -off switches.