Invention Grant
US08903030B2 Clock data recovery circuit with hybrid second order digital filter having distinct phase and frequency correction latencies 有权
具有混合二阶数字滤波器的时钟数据恢复电路具有不同的相位和频率校正延迟

Clock data recovery circuit with hybrid second order digital filter having distinct phase and frequency correction latencies
Abstract:
A clock data recovery circuit (CDR) extracts bit data values from a serial bit stream without reference to a transmitter clock. A controllable oscillator produces a regenerated clock signal controlled to match the frequency and phase of transitions between bits and the serial data is sampled at an optimal phase. A phase detector generates early-or-late indication bits for clock versus data transition times, which are accumulated and applied to a second order feedback control with two distinct feedback paths for frequency and phase, combined for correcting the controllable oscillator, selecting a sub-phase and/or determining an optimal phase at which the bit stream data values are sampled. The second order filter is operated at distinct rates such that the phase correction has a latency as short as one clock cycle and the frequency correction latency occurs over plural cycles.
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