Patent ID: 8553828
Filing Date: 2013-10-08
Classification: H03L,H04L

Abstract:
1. A clock data restoration device that restores a clock and data based on an input digital signal, the clock data restoration device comprising: a sampler portion that inputs a clock CK and a clock CKX which have a same frequency and whose phases differ by π, that inputs the digital signal and that samples, holds and outputs a value D of the digital signal at a time indicated by the clock CK and a value DX of the digital signal at a time indicated by the clock CKX; a phase comparison portion that compares, based on the value D and the value DX output from the sampler portion, phases of the digital signal and the clock CKX every period of the clock CKX, and that outputs a first phase difference signal which is a significant value when the phase of the clock CKX delays with respect to the digital signal or a second phase difference signal which is a significant value when the phase of the clock CKX advances with respect to the digital signal; a drive portion which inputs the first phase difference signal and the second phase difference signal output from the phase comparison portion, which, when it is assumed that Δ represents a variable, that 0<δ<N holds true, that the value δ is added to the variable Δ if the first phase difference signal becomes a significant value every period, that the value δ is subtracted from the variable Δ if the second phase difference signal becomes a significant value every period, that the value N is subtracted from the variable Δ if the value of the variable Δ becomes equal to or more than +N and that the value N is added to the variable Δ if the value of the variable Δ becomes equal to or less than −N, outputs, if the value of the variable Δ becomes equal to or more than +N, a third phase difference signal indicating this fact and which outputs, if the value of the variable Δ becomes equal to or less than −N, a fourth phase difference signal indicating this fact, a charge pump that outputs a charge and discharge current based on the third phase difference signal and the fourth phase difference signal output from the drive portion; a capacitive element that has a first end connected to an output end of the charge pump and a second end connected to a reference potential, that inputs the charge and discharge current output from the charge pump to the first end, that is charged and discharged and that outputs a voltage value at the first end; a potential adjustment portion that inputs the first phase difference signal and the second phase difference signal output from the phase comparison and that increases or decreases a potential at the first end of the capacitive element according to a phase difference indicated by the first and second phase difference signals; and a voltage control oscillator that inputs the voltage value at the first end of the capacitive element and that outputs, to the sampler portion, as the clock CK and the clock CKX, an oscillation signal having a frequency corresponding to the input voltage value.