Receive Enable Signal Timing Calibration in DDR Memory Interfaces

The patent applies preliminary action by performing receive enable timing calibration during the initial system boot-up phase. The memory controller adjusts the receive enable signal timing relative to the DQS signal before normal data transfer operations begin. This preliminary calibration establishes optimal timing margins that account for process, voltage, and temperature variations, ensuring reliable data sampling throughout subsequent operation without requiring continuous complex adjustments.

The patent implements feedback by using the DQS signal itself to control the receive enable signal timing. The receive enable signal is generated based on detecting specific transitions of the DQS signal (from unknown state to known state). This feedback mechanism ensures that the receive enable is asserted at the optimal moment when DQS is stable and known, preventing unknown pulses from reaching the sampling logic while maintaining efficient data transfer speed.

The patent minimizes calibration time by performing comprehensive PVT compensation during the initial system boot-up phase. The receive enable timing is calibrated to account for process, voltage, and temperature variations before normal operation begins. This preliminary action establishes robust timing margins that remain effective throughout subsequent operation, reducing the need for frequent periodic recalibration and minimizing time loss.

The patent applies self-service by enabling the memory controller to automatically perform its own receive enable timing calibration without requiring external intervention or complex manual setup. The calibration process uses internally available signals (DQS) and control logic to autonomously adjust the receive enable timing to optimal values, maximizing timing margins while keeping the initial setup process relatively simple and self-contained.