US Patent 7759999 Externally asynchronous internally clocked system

An Externally Asynchronous-Internally Clocked (EAIC) system that generates an internal clock signal includes a clock signal control block. The clock signal control block includes a pull-up unit that is activated in response to an input signal used to generate an internal clock signal; a pull-down unit that is activated in response to the input signal used to generate an internal clock signal, and a bypass unit that is provided between the pull-up unit and the pull-down unit, and selectively provides a signal path to the pull-down unit if the pull-down unit is activated and a signal path from the pull-up unit if the pull-up unit is activated.