Communication apparatus
A communication apparatus including a first unit which performs sampling of a synchronization pattern included in a signal with multiple clocks having different phases and identifies clocks where a predetermined synchronization pattern could be correctly sampled, from among the multiple clocks; a second unit which identifies, from among the multiple clocks, a first and second clock having a first clock edge which is nearest to the time point at which the data of the synchronization pattern changes and a second clock edge which is second nearest to the time point next to the first clock edge, respectively, the first and second clock edges being where the sampling of the synchronization pattern is performed; and a judgment section which judges one of clocks other than the first and second clocks, among the clocks with which the predetermined synchronization pattern was correctly sampled, to be used for sampling of the signal.
1. A communication apparatus comprising:
a storage section storing a first synchronization pattern;
a synchronization pattern detection unit receiving a signal including a second synchronization pattern to sample said second synchronization pattern with a plurality of clocks, phases of said plurality of clocks being different from each other, and comparing said first synchronization pattern with results of sampling said second synchronization pattern to identify a clock or clocks among said plurality of clocks, said first synchronization pattern being sampled correctly with said identified clock or clocks;
a phase comparison unit identifying a first clock and a second clock among said plurality of clocks, a data of said second synchronization pattern changing between an edge of said first clock and an edge of said second clock; and
a phase judgment section coupled to said synchronization pattern detection unit and said phase comparison unit to identify a third clock to be used for sampling said signal among said identified clock or clocks,
wherein said third clock has a different phase from said first and second clocks, and
wherein a phase difference between said third clock and a time point at which said data of said second synchronization pattern changes is larger than a phase difference between another clock included in said plurality of clocks and said time point.
2. The communication apparatus according to claim 1 , further comprising:
a Phase-Locked Loop (PLL) circuit outputting said plurality of clocks; and
a clock selection circuit coupled to said phase judgment section and said PLL circuit to receive said plurality of clocks, to select said third clock among said plurality of clocks, and to output selected third clock.
3. The communication apparatus according to claim 2 , further comprising:
a sampling circuit coupled to said clock selection circuit to receive said third clock and to sample said signal with said third clock.
4. A communication apparatus, comprising:
a Phase-Locked Loop (PLL) circuit configured to generate a plurality of multiphase clock signals each having a different phase timing;
a phase comparison unit configured to receive a data signal, and detect a data changing timing of the data signal based on the plurality of multiphase clock signals;
a phase judgment unit configured to select a sampling clock signal from the plurality of multiphase clock signals based on a detection result of the phase comparison unit;
a synchronization pattern detection unit configured to receive the data signal, and to determine which muitiphase clock signals of the plurality of multiphase clock signals detect a synchronization pattern of the data signal correctly;
wherein a phase difference between the sampling clock signal and the data changing timing is greater than a phase difference between the data changing timing and another clock signal of the plurality of multiphase clock signals, and
wherein the phase judgment unit selects the sampling clock signal from the multiphase clock signals of the plurality of multiphase clock signals that were determined to have detected the synchronization pattern of the data signal correctly.
5. The communication apparatus according to claim 4 , further comprising a sampling circuit configured to sample the data signal with the sampling clock signal.