US Patent 7183831 Clock switching circuit

A clock switching circuit suitably adapted to stable switching operation of high-frequency multiphase clock signals. The clock switching circuit receives two clock signals and selectively outputs one of the two clock signals in accordance with a selection signal. The clock switching circuit includes a switching controller that transfers the selection signal at the beginning of a period in which both of the two clock signals are active, and an internal selector that selectively outputs one of the two clock signals in response to the selection signal transferred from the switching controller.