Clock-and-data-recovery circuit, and serdes circuit based thereon

摘要

Disclosed is a clock-and-data recover circuit in which a data sampling circuit, a phase comparator, a phase controller and a phase interpolator make up a loop. The data sampling circuit samples serial input data, and the phase comparator receives an output from the data sampling circuit to detect the phase relationship between clock and the data. The phase controller outputs a phase control signal based on the result of phase comparison of the phase comparator to output a phase control signal. The phase interpolator receives a multi-phase clock composed of plural clock signals with different phases and supplies a clock signal having the phase interpolated based on the phase control signal, to the data sampling circuit. The clock and data recovery circuit further includes a second phase interpolator and a second data sampling circuit. The phase controller generates and outputs a second phase control signal to the second phase interpolator. The second phase interpolator receives the multi-phase clock and outputs a second clock signal having the phase interpolated based on the second phase control signal and supplies the second clock signal to the second data sampling circuit. The second data sampling circuit samples the input data based on the second clock signal from the second phase interpolator. Preferably, the second phase interpolator has a variably set threshold level for sampling the data.