Clock Buffer Delay Matching with Latch-Based Fine Alignment
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Solution Overview
Problem
Existing clock buffer integrated circuits face challenges in achieving precise alignment between input and output clock signals, leading to timing differences that are not adequately minimized, particularly due to limitations in delay adjustment accuracy and metastability regions.
Innovation Solution
A clock buffer integrated circuit incorporating a phase-locked loop or delay-locked loop for coarse alignment, combined with a latch receiver circuit and control mechanism to adjust fine delays, minimizes timing differences between input and output clock signals by using feedback loops to match delays in buffer slices and transmitter delays, achieving sub-ps accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase-locked loop or delay-locked loop is used for coarse alignment, then clock signal alignment is improved, but timing precision is limited by metastability regions and delay adjustment accuracy
Solution Approach 1:
The patent segments the delay adjustment into two distinct parts: a coarse alignment stage using phase-locked loop or delay-locked loop, and a fine alignment stage using a controllable delay element. This segmentation allows each stage to optimize for its specific function, with the fine alignment stage providing the necessary precision to overcome the limitations of the coarse alignment stage's metastability regions and delay adjustment accuracy.
Solution Approach 2:
The patent introduces a dynamic control mechanism where a state machine continuously monitors the alignment status and dynamically adjusts the controllable delay element. This dynamic adjustment allows the system to adapt to changing conditions and achieve optimal alignment precision by making real-time modifications to the fine delay parameter, thereby overcoming the static limitations of fixed delay adjustments in traditional loops.
2Measurement precision
If delay adjustment accuracy is increased to minimize timing differences, then clock alignment is improved, but device complexity increases
Solution Approach 1:
The control functionality is segmented into a dedicated state machine that specifically manages the controllable delay element. This separation of control logic from the main system reduces overall complexity by creating a modular, specialized control unit. The state machine implements a systematic approach to adjusting the fine delay parameter, simplifying the control process while achieving high timing precision.
Solution Approach 2:
The controllable delay element acts as an intermediary component between the coarse alignment stage and the final output. This intermediary provides a controlled, adjustable delay that can be precisely managed by the state machine, allowing for fine-tuning of the timing without requiring complex adjustments throughout the entire system. This intermediary approach simplifies the overall control architecture while achieving the desired timing precision.
Data Source
AI summary
A phase-locked loop or delay locked loop provides a coarse alignment between an input clock and an output clock. A latch receiver circuit provides an indicator of a delay error between the input clock and the output clock. The delay error is used by a control circuit or state machine to adjust a fine delay that affects the output clock signal timing relative to the input clock signal. The fine delay is adjusted to minimize the timing difference between the output clock signal and the input clock signal.