Patent ID: 8244142

Claim:
An optical receiver for receiving an incoming optical signal carrying symbols, the optical receiver comprising: an analog-to-digital converter (ADC) operating at a fractional sampling clock rate to convert an analog signal carrying the symbols to digital ADC output samples; an interpolator to interpolate at an interpolation clock rate different than the fractional sampling clock rate between digital values derived from the digital ADC output samples to provide moving interpolations; and an interpolation feedback loop to synchronize the moving interpolations with the symbols, the interpolation feedback loop comprising a seed generator to compute seeds based in part on a ratio between the fractional sampling clock rate and the interpolation clock rate, an accumulator to provide interpolation fractions at the interpolation clock rate, the accumulator being configured to increment by the seeds to compute the interpolation fractions, and generate an overflow when an increment by a current one of the seeds causes a modulus of the accumulator to be exceeded, wherein the interpolator is configured to use the interpolation fractions to interpolate between the digital values to compute values of the moving interpolations, operate with the interpolation clock rate to respond to the overflow by reading a new one of the digital values, and use a current one of the interpolation fractions to interpolate between the new digital value and a previous one of the digital values when the accumulator generates the overflow or to interpolate by the current interpolation fraction between a previous one of the digital values and a second previous one of the digital values when the accumulator does not generate the overflow.