Calibrating a quadrature receive serial interface

A quadrature receive serial interface circuit comprising:

• a first phase rotator;
• a second phase rotator;
• a plurality of first sampling latches for sampling received serial data, wherein the first phase rotator is configured to generate in-phase 0° and 180° clock signals and the second phase rotator is configured to generate quadrature phase 90° and 270° clock signals, and the generated in-phase 0° and 180° clock signals are used as clocking signals for a first pair of the plurality of the first sampling latches;
• and the generated quadrature phase 90° and 270° clock signals are used as clocking signals for a second pair of the plurality of the first sampling latches;
• and
• a pseudo random bit sequence (PRBS) checker configured to calibrate the first phase rotator and the second phase rotator sequentially using sampled pseudo random bit sequence (PRBS) data bits.

A computer program product for calibrating a quadrature receive serial interface circuit, the quadrature receive serial interface circuit comprising a first phase rotator and a second phase rotator for generating quadrature clock signals of identical frequency, a plurality of first sampling latches for sampling received serial data, where the first phase rotator generates in-phase 0° and 180° clock signals and the second phase rotator generates quadrature phase 90° and 270° clock signals, and the generated in-phase 0° and 180° clock signals are used as clocking signals for a first pair of the plurality of the first sampling latches;

• and the generated quadrature phase 90° and 270° clock signals are used as clocking signals for a second pair of the plurality of the first sampling latches, and a pseudo random bit sequence (PRBS) checker, the computer program product comprising:
• a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code executable by one or more computer processors to perform an operation comprising:
• receiving a pseudo random bit sequence (PRBS) of data bits for calibrating the quadrature receive serial interface circuit;
• setting the PRBS checker to sample at least one-half of the received PRBS data bits;
• adjusting the first phase rotator to center a data eye of the received sampled one-half PRBS data bits;
• setting the PRBS checker to sample all of the received PRBS data bits;
• and
• adjusting the second phase rotator to center the data eye of the received sampled all PRBS data bits to complete calibration of the quadrature receive serial interface circuit.