Separate Data Strobe Delay Calibration for DDR Timing Skew
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Solution Overview
Problem
As data transfer rates increase in computing platforms, timing skew and duty cycle variations in data strobe signals become significant issues, affecting signal integrity and limiting performance in interfaces like DDR memory, where data is latched in response to rising and falling edges of the strobe signal.
Innovation Solution
The use of multiple delay circuits to position the rising and falling edges of the data strobe signal, compensating for timing skew and duty cycle variations by generating delayed strobe signals that align with optimal data sampling times, thereby improving signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transfer rate is increased, then productivity is improved, but timing skew and duty cycle variations worsen
Solution Approach 1:
The patent divides the single strobe signal into multiple separate strobe signals (e.g., DQS0, DQS1, DQS2, DQS3) that can be independently delayed and calibrated. This segmentation allows each strobe signal to be individually adjusted to compensate for timing skew and duty cycle variations, thereby maintaining signal integrity at higher data transfer rates.
Solution Approach 2:
The patent introduces separate delay circuits that can independently adjust the timing parameters of each strobe signal. By changing the delay parameters of individual strobe signals, the system compensates for timing skew and duty cycle variations, allowing higher data transfer rates to be achieved while maintaining signal integrity.
2Measurement precision
If separate delay circuits are used for multiple strobe signals, then timing precision is improved, but device complexity increases
Solution Approach 1:
The patent designs delay circuits that can serve multiple functions: they can delay different strobe signals by different amounts, they can be individually calibrated, and they can compensate for both timing skew and duty cycle variations. This multi-functionality reduces the need for additional separate compensation circuits, thereby limiting the increase in device complexity.
Data Source
AI summary
Embodiments for positioning rising and/or filling edges of data strobe signals are disclosed. One example embodiment may comprise receiving a data signal, positioning an edge of a first delayed data strobe signal associated with the data signal by a first programmable amount, and positioning an edge of a second delayed data strobe signal associated with the data signal by a second programmable amount, wherein the second delayed data strobe signal is shifted approximately one bit-time in relation to the first delayed data strobe signal.