DDR Memory Interface Calibration for Byte-Lane CAS Latency
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Solution Overview
Problem
DDR memory controllers face challenges in efficiently capturing and processing memory data due to timing skews and silicon real estate constraints, requiring complex calibration and additional delay elements that increase latency and silicon usage.
Innovation Solution
A DDR memory controller design that uses core domain clocking mechanisms and self-configuring logic to dynamically calibrate timing, eliminating delay elements on data inputs and utilizing a core clock delay element for dqs, thereby reducing silicon real estate and latency while adapting to system timing irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If delay elements are added to compensate for timing skews in each byte lane, then timing calibration is improved, but silicon real estate increases and latency increases
Solution Approach 1:
The patent merges the timing calibration function into a single shared delay element located in the core domain, rather than having separate delay elements in each byte lane. This consolidation reduces silicon real estate while maintaining timing calibration capability across all byte lanes through unified control.
Solution Approach 2:
The patent introduces a shared delay element as an intermediary component that mediates timing adjustments for multiple byte lanes. This single delay element acts as a central control point that can compensate for timing skews across the entire memory interface without requiring individual delay elements in each lane.
2Manufacturing precision
If delay elements are added to compensate for timing skews, then timing calibration is improved, but latency increases
Solution Approach 1:
The shared delay element in the core domain performs timing calibration autonomously without requiring additional delay elements in each byte lane. This self-service approach reduces the overall latency by eliminating redundant delay stages while maintaining timing accuracy through centralized control.
3Adaptability or versatility
If complex calibration circuits are implemented in each byte lane, then adaptability to timing irregularities is improved, but device complexity increases
Solution Approach 1:
The shared delay element in the core domain serves as a universal calibration mechanism that handles timing irregularities for all byte lanes simultaneously. This multi-functional approach provides adaptability to timing skew, data setup/hold violations, and other irregularities across the entire memory interface without requiring separate calibration circuits in each lane.
4Measurement precision
If additional calibration circuits are added during power-on initialization, then measurement precision of timing skews is improved, but device complexity increases
Solution Approach 1:
The patent extracts the timing measurement and calibration function from individual byte lane circuits and concentrates it in a single shared delay element in the core domain. This extraction reduces device complexity by removing redundant calibration circuits while maintaining measurement precision through centralized timing analysis and adjustment.
Data Source
AI summary
A method for quickly calibrating a memory interface circuit from time to time in conjunction with operation of a functional circuit is described. The method uses controlling the memory interface circuit with respect to read data capture for byte lanes, including controlling CAS latency compensation for the byte lanes. In the method control settings for controlling CAS latency compensation are determined and set according to a dynamic calibration procedure performed from time to time in conjunction with functional operation of a circuit system containing one or more memory devices connected to the memory interface circuit. In the method, determining and setting the control settings for controlling CAS latency compensation is performed independently and parallely in each of the byte lanes.