Data Transition Detection for SDRAM Skew Compensation
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Solution Overview
Problem
Conventional SDRAM data reading methods face challenges in maintaining optimal setup and hold margins due to skews in data signals caused by instability and cross-talk, making it difficult to capture data accurately, especially with increased data transition rates and fluctuations in power levels.
Innovation Solution
A method and apparatus that detect data transitions to generate a pulse signal, which is used as a trigger for capturing data, eliminating the need for complex delay lines and clock synchronization modules by determining setup times based on buffer or inverter delays, and generating initial pulses during preamble periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data strobe signals DQS are delayed by 90° or 120° to optimize setup and hold margins, then data reading stability is improved, but device complexity increases due to requirement for delay lines and clock synchronizing modules
Solution Approach 1:
The patent extracts the data transition detection function from the complex delay line and clock synchronizing module system. By directly detecting when data transitions occur and using that detection point as the trigger, the invention eliminates the need for separate delay elements and clock synchronization circuits, thereby reducing device complexity while maintaining reading stability
Solution Approach 2:
The data transition detection circuit uses the data signal's own transition characteristics to generate the trigger signal. The detection circuit monitors the data signal and automatically generates a pulse at the moment of transition, making the system self-regulating without requiring external delay lines or clock synchronization mechanisms
2Reliability
If data strobe signals DQS are delayed to center transitions between data signal transitions, then setup margin and hold margin are maximized, but measurement precision decreases due to difficulty in accurately detecting data transition timing
Solution Approach 1:
The data transition detection circuit continuously monitors the data signal and provides feedback about its transition state. This feedback mechanism enables precise detection of the exact moment data transitions occur, allowing the system to accurately determine when to capture the data without relying on predetermined delay values
Solution Approach 2:
The patent replaces the mechanical/electrical delay line system with an electronic detection-based timing mechanism. Instead of using physical delay elements to center the trigger, the system uses electronic detection circuits to precisely identify the moment of data transition, achieving higher measurement precision
Data Source
AI summary
Provided are an apparatus and a method of capturing data by using a data transition of a data signal. The method includes detecting a data transition of a data signal input from an external source, generating a pulse signal corresponding to the detected data transition, and capturing the data signal by using the generated pulse signal as a trigger. Accordingly, stable capturing of data can be performed without changes in margins even when data bits of the read data enter a controller at different times due to skews.