US Patent 7514766 Semiconductor device

A semiconductor device in which the threshold voltage of transistors is controlled through the applied substrate bias and having relatively small size. The semiconductor device includes: a clock signal line; a shield wiring for shielding the clock signal line from another interconnection; and a substrate bias generating circuit. The substrate bias is applied through the shield wiring to a region on which a transistor is formed. The threshold voltage of the transistor depends to the substrate bias applied to the transistor.