Multi-Cycle Write Leveling for DDR Signal Edge Alignment
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Solution Overview
Problem
Conventional DDR memory systems face challenges in accurately aligning signal edges of the clock signal and data strobe signals after the write leveling process, leading to potential misalignment and failure in data acquisition due to varying propagation delays through different layout traces on the memory bus.
Innovation Solution
A multi-cycle write leveling process is implemented, where the PHY circuit is equipped with a control circuit to adjust delaying times of clock, data strobe, and address/command signals, ensuring accurate alignment of signal edges through iterative adjustments and cycle-based delay mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the write leveling process is performed to align signal edges of clock signal and data strobe signals, then the timing alignment is improved, but the propagation delay variations through different layout traces cause misalignment and data acquisition failure
Solution Approach 1:
The patent segments the write leveling process into multiple cycles, where each cycle performs write operations followed by read operations. This segmentation allows independent adjustment of write timing and read timing parameters, enabling precise alignment of signal edges while accounting for different propagation delays in layout traces.
Solution Approach 2:
The patent implements a feedback mechanism where the read data from each write leveling cycle is compared with expected values. Based on this feedback, the system adjusts write timing and read timing parameters iteratively until optimal alignment is achieved, ensuring both precision and reliability.
2Measurement precision
If the PHY circuit adjusts delaying times of clock, data strobe, and address/command signals through iterative adjustments, then the signal edge alignment is improved, but the process complexity increases
Solution Approach 1:
The control circuit adjusts timing parameters in segmented cycles, with each cycle focusing on specific write and read timing adjustments. This segmentation simplifies the control logic within each cycle while achieving overall precise alignment through multiple iterations.
Solution Approach 2:
The patent employs periodic write leveling cycles, where each cycle performs a complete sequence of write operations, read operations, and timing adjustments. This periodic structured approach simplifies the control circuit design by repeating a standardized adjustment pattern rather than requiring complex continuous control.
Data Source
AI summary
A method for controlling a multi-cycle write leveling process in a memory system is provided. After a write leveling process is completed and before a write training process is performed, the multi-cycle write leveling process is performed. Consequently, when a DDR memory of the memory system receives a clock signal and a first data strobe signal, the DDR memory can confirm that the signal edges of the clock signal and the first data strobe signal are aligned with each other and the signal edges are accurate.