Oversampling data recovery apparatus and method
AssigneeMacronix International Co., Ltd.
InventorsChu-Hua Lee, Pi-Fen Chen
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Abstract
An open-loop data recovery apparatus and method utilizing an oversampling technique is provided, by which the occurrence of data transitions is counted and a proper sampling clock phase is decided. Counters with variable thresholds are used to monitor the occurrence of phase transitions for a phase selection circuit to determine a preferred phase for recovery of sampled data. The thresholds of the counters are further adjusted in reference with the preferred phase decided by the phase selection circuit.
Claims24
An oversampling data-recovery apparatus, comprising:
- a data sampler configured to receive a serial data stream with an L-phase clock and to output N samples X1 to XN, with M samples per bit;
- a phase decision circuit comprising a plurality of counters each having at least a first adjustable threshold and a second threshold, wherein the phase decision circuit is configured to receive said plurality of samples and to output phase selection information based on counts stored in said counters;
- and
- a multiplexer circuit configured to receive the samples X1 to XN and the phase selection information, wherein the multiplexer circuit selects one of the plurality of samples per bit to output recovered data.
A method of recovering oversampled data, comprising:
- oversampling by M times an input serial data steam to produce N samples with M samples per bit;
- detecting phase transitions between successive ones of the samples;
- determining a majority of the phase transitions, wherein the majority corresponds to one sample of the M samples for each bit;
- incrementing counters based on the majority of phase transitions;
- and
- selecting a set of samples based on a counter reaching an adjustable threshold prior to other counters reaching the adjustable threshold.
Dependencies are inferred from the claim text.