Methods and apparatus for performing runtime data eye monitoring and continuous data strobe calibration

摘要

Integrated circuits may include memory interface circuitry operable to communicate with system memory. The memory interface circuitry may receive data (DQ) and data strobe (DQS) signals from system memory during read operations. The memory interface circuitry may include startup calibration circuitry and runtime calibration circuitry. The startup calibration circuitry may be used upon device startup to perform a one-time data de-skew and DQ/DQS centering. The runtime calibration circuitry may include at least two data sampling circuits, a first of which is used in active mode to latch incoming data and a second of which is used in redundant mode to obtain data eye boundary information on a continuous basis. The received DQS signal may be adjusted based on the obtained eye boundary information so that DQS properly positioned within the data eye periodically or on an as-needed basis.

主权项

1. An integrated circuit that receives a data signal and a data strobe signal from external memory, comprising:
a first data sampling circuit that receives and latches the data signal using a first version of the data strobe signal; a second data sampling circuit that receives and latches the data signal using a second version of the data strobe signal, wherein the first and second data sampling circuits are configured to alternate between an active data sampling mode and a redundant data eye monitoring mode; and a comparator circuit that compares the data signal latched by the first data sampling circuit to the data signal latched by the second data sampling circuit to determine whether the first version of the data strobe signal satisfies performance criteria.