CLOCK AND DATA RECOVERY CIRCUIT USING DIGITAL FREQUENCY DETECTION

摘要

According to embodiments of the present invention, a clock data restoring device comprises a phase detecting unit, a charge pump, a loop filter, a voltage control oscillator, and a frequency detecting unit. The voltage control oscillator has an oscillation frequency changing according to a frequency control signal, and outputs an oscillation signal. The frequency detecting unit comprises: a standard frequency demultiplyer for generating a count active section signal from a standard clock signal according to a standard frequency demultiplying ratio; a counter for generating an oscillation count signal based on an oscillation signal of the voltage control oscillator according to the count active section signal; and an oscillation frequency control unit for outputting a frequency control signal by comparing a target count signal and an oscillation count signal determined according to a target frequency of an oscillation signal.