Clock data recovery apparatus

Abstract

A clock data recovery apparatus includes a phase looked loop unit, a voltage control delay line, a phase detection unit, a charge pump unit, and a loop filter unit. The phase looked loop unit outputs a plurality of clock signals which are different from each other in phase and of which frequency is lower than that of data. The voltage control delay line outputs recovered clock signals by delaying the clock signals according to input voltage levels. The phase detection unit outputs recovered data in synchronization with the clock signals, respectively and outputs increment and decrement signals which have wider pulse width than the data by comparing the recovered clock signals with the data. The charge pump unit outputs a corresponding current in response to the increment and decrement signals. The loop filter unit determines an amount of delay in the voltage control delay line by outputting the voltage.