DDR Clock Phase Alignment Using a Replica-Free Delay Loop
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Solution Overview
Problem
Conventional calibration techniques for phase alignment between clock and command signals in DDR DRAM modules are limited by excessive dependence on feedback, inaccurate path replication, and difficulties in physical implementation, particularly in high-speed and low-power modules, leading to component mismatch and on-chip variations.
Innovation Solution
A method and system that aligns clock signals with command signals using a phase detection circuit, where both signals are delayed by a predetermined amount, and the controllable delay circuit adjusts until they are in phase, eliminating the need for a replica path and simplifying implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration techniques are used for phase alignment, then phase alignment between clock and command signals is achieved, but excessive dependence on feedback from DDR DRAM memory is required
Solution Approach 1:
The patent introduces a phase detection circuit as an intermediary component that directly compares the clock signal and command signal phases without requiring feedback from the DDR DRAM memory. This mediator enables phase alignment measurement while eliminating the complex feedback loop required in conventional techniques.
2Measurement precision
If replica path is created for phase alignment, then path matching between clock and command paths is achieved, but variations across actual path and replica path cause inaccurate results
Solution Approach 1:
The patent extracts the phase detection function from the complex replica path structure and implements it through a dedicated phase detection circuit. This separates the measurement function from the signal paths, eliminating the variations and inaccuracies introduced by replica path mismatches.
3Measurement precision
If replica path is created for phase alignment, then path replication is attempted, but difficulty in physical implementation on IC is encountered
Solution Approach 1:
The phase detection circuit serves as an intermediary that directly measures phase differences between clock and command signals without requiring physical replica paths. This approach simplifies the manufacturing process by eliminating the complex task of creating and matching replica paths on the IC.
4Measurement precision
If conventional calibration methods are used, then phase alignment is attempted, but component mismatch and on-chip variations create inaccuracies
Solution Approach 1:
The patent implements a direct feedback mechanism through the phase detection circuit that continuously monitors the phase relationship between clock and command signals. This real-time feedback enables dynamic adjustment and compensation for component mismatch and on-chip variations, achieving accurate phase alignment despite these harmful factors.
Data Source
AI summary
A system and method for aligning clock signals in a DDR DRAM module is disclosed. The system includes a phase detector circuitry, a controllable delay circuit, a first delay circuit and a synchronizing circuit. A clock signal is simultaneously transmitted through the first delay circuit and the controllable delay circuit. Subsequently, the clock signals transmitted through the first delay circuit and the controllable delay circuit are captured at the output thereof, and fed as inputs to the phase detector circuitry. The phase detector circuitry determines whether the clock signals are in phase, and accordingly adjusts the delay associated with the controllable delay circuit until the two clock signals are determined to be in phase.