Memory Clock Duty Cycle Calibration for Reliable Read/Write Timing
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Solution Overview
Problem
In memory subsystems, existing calibration methods for signal sampling within eye patterns often fail to ensure the duty cycle of clock signals is within a specified range, affecting data transmission reliability and susceptibility to noise.
Innovation Solution
A method and apparatus for duty cycle correction in memory subsystems, involving a first calibration to adjust the duty cycle of a clock signal, followed by a second calibration that synchronizes reads and adjusts the duty cycle further to ensure the widest possible range of delay values for correct data reading, thereby maintaining the duty cycle within a specified range and optimizing the eye pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing calibration methods are used for signal sampling within eye patterns, then signal sampling can be performed, but the duty cycle of clock signals cannot be ensured to be within a specified range, affecting data transmission reliability
Solution Approach 1:
The calibration process is divided into two distinct phases: a first calibration that performs reads synchronized by a second clock signal to determine delay values, and a second calibration that adjusts the duty cycle of the first clock signal based on the delay values. This segmentation allows each calibration to focus on specific parameters without interference, ensuring both reliability and precision.
Solution Approach 2:
The system implements feedback by using the delay values determined during the first calibration to guide the duty cycle adjustments in the second calibration. The calibration process continuously monitors and adjusts parameters based on measured performance, ensuring the duty cycle converges to the specified range while maintaining data transmission reliability.
2Manufacturing precision
If duty cycle adjustments are made during calibration, then the duty cycle can be maintained within a specified range, but additional calibration steps are required increasing system complexity
Solution Approach 1:
The patent merges the duty cycle adjustment function with the existing calibration framework by implementing duty cycle adjustments as a secondary calibration step that builds upon the first calibration results. Rather than creating a separate duty cycle adjustment system, the adjustments are integrated into the calibration sequence, sharing control logic and measurement infrastructure.
3Device complexity
If the duty cycle is not maintained within a specified range, then the calibration process is simpler, but the system becomes more susceptible to noise and errors
Solution Approach 1:
The system performs preliminary duty cycle calibration adjustments before normal data transmission operations begin. By establishing the correct duty cycle range in advance through the second calibration phase, the system prepares the clock signals to be optimally conditioned for reliable data transmission, preventing noise susceptibility before it occurs.
Data Source
AI summary
A method and apparatus for performing duty cycle correction with read/write calibrations is disclosed. A first calibration is performed in a memory subsystem having a memory and a memory controller. The first calibration includes conveying a first clock signal from the memory controller to the memory, and determining the duty cycle of the first clock signal. If the duty cycle is not within a specified range, the duty cycle is adjusted and the process repeated. After the duty cycle of the first clock signal is within the specified range, a second calibration is performed, the second calibration including conveying a second clock signal from the memory to the memory controller. The duty cycle of the first clock signal may be further adjusted based on the second calibration.