Read channel operable to calibrate a coefficient of a filter, such as an FIR filter, disposed before an interpolated-timing-recovery circuit, and related integrated circuit, system, and method

摘要

An embodiment of a read channel includes a filter, an interpolator, a recovery circuit, an error detector, a reverse interpolator, and a filter calibrator. The filter is operable to receive a raw sample of a signal and a coefficient-correction value, generate a filtered sample from the raw sample and a pre-established coefficient, and change the coefficient in response to the coefficient-correction value. The interpolator is operable to interpolate the filtered sample, and the recovery circuit is operable to generate a data symbol from the interpolated sample. The error detector is operable to generate an ideal sample from the data symbol and to generate a difference between the ideal sample and the interpolated sample, and the reverse interpolator is operable to reverse interpolate the difference. The filter calibrator is operable to receive the raw sample and to generate the coefficient-correction value from the raw sample and the reverse-interpolated difference.

主权项

1. A read channel, comprising:
a filter operable to
receive a raw sample of a signal and a coefficient-correction value,generate a filtered sample from the raw sample and a pre-established coefficient, andchange the coefficient in response to the coefficient-correction value; an interpolator coupled to the filter and operable to interpolate the filtered sample; a recovery circuit coupled to the interpolator and operable to generate a data symbol from the interpolated sample; an error detector coupled to the interpolator and to the recovery circuit and operable to
generate an ideal sample from the data symbol, andgenerate a difference between the ideal sample and the interpolated sample; a reverse interpolator coupled to the error circuit and operable to reverse interpolate the difference; a calibrator coupled to the reverse interpolator and to the filter, and operable to
receive the raw sample, andgenerate the coefficient-correction value from the raw sample and the reverse-interpolated difference; and wherein the calibrator is operable to generate the coefficient-correction value by:
auto-correlating the raw sample to obtain an auto-correlation value;cross-correlating the raw sample and the reverse-interpolated difference to obtain a cross-correlation value;generating the coefficient-correction value from the quotient of the cross-correlation and auto-correlation values.