US Patent 8677166 Semiconductor devices and systems-on-chip having the same

A semiconductor device includes a power gating unit, a combinational logic unit and a clamping unit. The power gating unit is turned on to output an internal signal at an output electrode based on an input signal or turned off according to operation modes. The combinational logic unit includes an input electrode directly connected to the output electrode of the power gating unit through a data line, and generates an output signal based on the internal signal received through the data line. The clamping unit is turned on to clamp the internal signal at a logic high level or at a logic low level or turned off according to the operation modes. The semiconductor device clamps the output electrode of the power gating unit without degrading an operation speed of the semiconductor device.